9\ University Free State
11111111111111111111111111111111111111111111111111111111111111111111111111111111
34300000730311
Universiteit Vrystaat
THE STRATIGRAPHY AND
GEOCHEMISTRY OF THE RIETGAT
FORMATION BETWEEN /
ALLANRIDGE AND BOTHAVILLE,
FREE STATE PROVINCE. ./
By
JEREMY CROZIER
Thesis submitted in,fulfilment of the requirements
for thedegree.of '
:., ':." '. I"
MASTER OF SCIENCP, ,
: • •• t
In the Faculty of Science
Department of Geology
University of the Orange Free State
Bloemfontein
Republic of South Africa
\
\,
FEBRUAR-Y 2001
Supervisor: Prof. W. A. van der Westhuizen
Co-Supervisor: Dr. H. de Bruiyn
r s itei t von dl .
oranje-Vrystaat
BLO"f'1fO TEl"
3 - DEC 2001
\ UQV$ SA~Ol_r.1-l ~TEEK.__
ABSTRACT
An extensive lithological and geochemical appraisal of the Rietgat Formation was
undertaken. This involved the collection and analysis of 389 borehole core samples in
the area between Allanridge and Bothaville, as well as 23 outcrop samples from the
T'Kuip hills. Given the relative visual and petrographic homogeneity of the lavas of the
Rietgat Formation, the purpose of the exercise was to establish whether these rocks
may be sub-divided on the basis of their geochemistry. Five distinct lava units were
identified according to their P20S/Zr characteristics and accordingly named Units 1-5.
Conventional discrimination diagrams were applied to the data and elucidated a
.rhyodacitic-andesitic-basaltic affinity for the lava series. Two sedimentary units (the
Upper Sedimentary Horizon and Lower sedimentary Horizon) were also recognised.
Using a selection of incompatible elements, (P20S, Ti02, Zr, Nb, V and Y) in addition
to limited REE data, it was proven .with reasonable confidence (in the absence of
isotopic data) that the lavas of the Rietgat Formation represent the partial melting of an .
enriched mantle. source, followed by subsequent fractionation of this material. The
REE characteristics of the lavas are consistent with contamination and fractionation,
which have been explained here ill tern is uf all APC process. It is proposed that the 5
distinct lava units were in fact consanguinous and were the product of an RTF-type
magma chamber in the lower crust.
Petrographic and XRD data indicate lower greenschist facies metamorphism of the
lavas. Fluid inclusion studies determined that the quartz veining in the lavas is of lower
temperature and lower pressure than that characterised by the metamorphic facies. The
veining is therefore interpreted as being of later origin.
Interpreted sedimentary processes facilitate the identification of graben structures due
to the presence of clastic-wedge type sedimentation in the vicinity of fault scarps. Field
and geochemical evidence in combination are consistent with rifling and associated
magmatism of the Rietgat Formation.
TABLE OF CONTENTS:
Abstract............................................ . - " I
Table ofContents · ii
CHAPTER 1: INTRODlUCTION 1
1.1 Background : : 1
1.2 Study Area 3
1,3 Research Objectives ; ., 7
1.4 Previous Research :.8
1.4.1 Pioneering Studies , , .: 8
1.4.2 Broader scale interpretation of the Ventersdorp Supergroup ; ;9
1.4.3 Structure 'and Tectonics v ; : , : 9
1.4.4 Geochemistry ;·10
1.4.5 MineraIParagenesis 10 '.
i.5 Analytical Methods : ; ; 10
CHAPTER 2: STRA TIGRAPHY OlF THE RIETGAT lFORMATION 12
'2.1 Introduction 12
. 2.2 Previous Subdivision and Stratigraphy ;· 12
2.3 Geochronology ó .J 5
2.4 Subdivision of the Rietgat Formation in the study area 19
2.5 Basic geochemical subdivision of the Rietgat Formation 20
2.6 Petrography ; 22
2.6.1 Lithological and mineralogical descriptions 23
2.6.1.1 Lower Sedimentary Horizon (LSH) , 23
2.6.1.2 UNIT 1 (Lower Garfield Member) 27
2.6.1.3 UNIT 2 (Upper Garfield Member) 32
II
2.6.1.4 UNIT 3 (Central Rietgat Member) 36
2.6.1.5 UNIT 4 (Upper Rietgat Member - Non-amygdaloidal) 38
2.6.1.6 UNIT 5 (Upper Rietgat Member - Amygdaloidal) 39
2.6.1.7 UpperSedimentary Horizon (USH) .43
2.6.1.8 Intrusive Rocks 47
2.7 Structural Geology 48
2.8 Summary ofStratigraphy and Discussion 53
CHAPTER-3: MlfNERALOGY 68
3.1 Introduction 68
3.2 Briefnote on previous Work 68
3.3 Techniques Employed 69
3.4 Unit by Unit petrographic appraisal of the Rietgat Formation 71
3.4.1 Lower Sedimentary Horizon (LSH) 71
3.4.2 UNIT 1 (Lower Garfi.eldMember) 72 .
3.4.3 UNIT 2 (Upper Garfield Member 76
3.4.4 {.INTT3 (Central Rietgat Member) , 77 ·on.;:
3.4.5 UNIT 4 (Upper Rietgat Member-Non-arnygdaloidal) 81
3.4.6 UNIT 5 (Upper Rietgat Member - Amygdaloidal) 82
3.4.7 Upper Sedimentary Horizon (USH) 82
3.4.8 Intrusive Rocks 85
3.4.9 Pseudotachylites , 86
3.5 Mineralogical trends as identified by XRD 89
3.5.1 Introductory note 89
2L6 Normative mineralogical classification of the Rietgat Formation 91
3.6.1 Introduction 93
3.7 Veins and Vuggy quartz occurrences ; 98
3.7.1 Thermo metric Analysis 99
3.7.2 Interpretation of results 100
3.7.3 Discussion and Interpretation of Mineralogy : ; 101
III
CHAPTER 4: GEOCH.EMICAL STRAT1GRAPHY 105
4.1 Introduction 105
.. 4.2 Previous work ······· 106
4.3 The geochemical stratigraphy of the Rietgat Formation 107
4.3.1 Univariate Analysis: geochemical variation with stratigraphic height.. l07
4.3.2 Bivariate Analysis: scatter plots : 109
4.3.3 Multivariate Statistics 121
4.3.3.1 Discriminant Function Analysis ·············· 122
4.4 Application of DFA to Study Area 125
4.5 Application of OFA outside Study Area 127
4.6 Discussion and Conclusions 132
CHAPTER 5: GEOCHEM][CAL CLASSU'][CAT][ON, MAGMAT][C AFF][N][TY,
TECTONIC SETT][NG AND PETlROGENES][S 134
5.1 Introduction 134
5.2 Previous work 134
5.3 Geochemical classification of the Rietgat Formation ·134
5.3.1 Application of conventional techniques 135
5.3.1.1 Discrimination according to generic name 136
5.3.1.2 Discrimination according to magmatic affinity 136
5.3.1.3 Discrimination according to tectonic setting 137
5.3.1.4 Notes of caution with regard to discrimination diagrams 144
5.4 Petrogenesis 145
5.4.1 Process Identification 145
5.4.2 Identification of variation trends in elemental data 147
5.4.2.1 Bivariate plots of selected variables 147
5.4.2.2 Normalised multi-element diagrams ·148
5.5 Genetic modelling ··· ····································1·5··5··
5.6 A tectono-stratigraphic-petrogenetic model for the evolution of the Rietgat
Formation 160
iv
5.6.1 Tectonic Background 161
5.6.2 An 8-stage model for the development of the study area 161
5.7 Discussion and conclusions 169
CHAPTlER 6: SUMMARY AND PRlESlENTA ll0N OIFTYPE SlECTJON .1n
6.1 General Characteristics and Lithology :": 171
6.2 Mineralogy and Petrography 172
ó.3 Geochemical Stratigraphy .. ; 173
6.4 Magmatic classification and tectonic setting 173
6.5 Petrogenesis 174
6.6 Proposed Reference Section 174
6.7 Scope for Future Study 176
Acknowledgements 177
References 178 .
APPlENDIX 1 - ANALYTICAL PROClEDURlES 193
A1.1 Rare Earth Elements 193
Al.2 XRF 194
APPlENDIX 2: ANALYTICAL DATA - XRD ...........................................•.... 196
APPENDL""X3: ANALYTICAL DATA - XRF 202'
v
CHAPTER 1: INTRODUCTION.
1.1 Background.
_/'-
The late Archaean to early Proterozoic Ventersdorp Supergroup comprises a major
-'
volcano-sedimentary province situated on the Kaapvaal eraton of South Africa (Figure
1.1). The succession is relatively well preserved and largely undeformed, covering an
elliptical area in excess of 200,000km2 (Winter, 1995; Van der Westhuizen et al.,
1991; Myers, 1990). The Ventersdorp Supergroup consists of three subdivisions,
which in ascending order are the Klipriversberg and Platberg Groups, followed by the
sediments and lavas of Bothaville and Allanridge Formations respectively (Figure
1.2). Recent isotope studies (Armstrong ef al., 1991; Robb ef al., 1991) suggest ages
in the order of2700 Ma for the entire Supergroup.
The Rietgat' Formation is the uppermost unit of the Platberg Group (Figure 1.2) and
comprises a geochernically hetrogeneous assemblage of mafic and felsic lavas and
tuffs in association with chemical and clastic sediments. Occasional weathering
surfaces (Winter,1976) seen in the underlying Makwassie Formation, suggest local
disconformity between the Makwassie and Rietgat Formations due to terrestrial
exposure. Elsewhere this relationship is conformable. Over large areas the Rietgat
Formation is overlain unconformably by the sediments of the Bothaville Formation.
Where the Bothaville Formation is absent from the sequence, the lavas of the
Allanridge Formation come into direct contact with those of the Rietgat Formation.
I The name Rietgat comes from the farm' Rietgat', on which the type borehole (RG I) for the Formation
is situated (Winter, 1976; SACS, 1980).
Chapter 1 - Introduction - I
'.T..l.
(JCl
22' 24' 26' 28' ..~ ..-.3!l:~Zl~~~~E... 32' .34'C 18' 20'- ._ ... _. MESStNA IJ 'j{,PAFURI"'I('D (' . \- / LOUIS TRICHARDT ':,~r:. IJ \:BOTSWANA ~ ~! PIETERSBURG I
t...i. I IJ IJ PHALA\BORW Atil 24' ...../,..:
sSr. ": ., I:- II~
C....l.. Ii", \ /">""-; h \!
;:l : \ / ., ... , ....... _/ IJ PRETORIA SI i ,.., '
0 i: Ir _l 0 :' ...",~>-+, 1 I /MBABANE)
ft 26' : l .. .:Il !I 'v..._.._ ..r , SWAZI· \I
< '\ LAND
,
1'.._. _
~ \....i
;:l _"V.~..... \~BOTHAVILLE VRYHEID D
""'I NAMIBIA IJ ALLANRIDGE
IJJ
Cl.
.0a 28' .rL, i
UPinGTON 28'
,..) ' c-»
·D
",,..".',.-.."."...s..'.,..•.•. . r,/· ........
r:/) C:9 /.... \-.Il
~ BLOEMFONTEIN !/ '....
'"~0 < LESOTHO (/
""'I
(]Q DURBAN
""'I R'::PUBLlC .~ \. ....~_...;
.0g 30' OF SODIUMGROUP \..,._. j ~'t-~
30'
~ OC;
,.-._ SOUTH AFRICA
PJ ~ ..... ~'t-~
~ '6 ~Q
o ""'I
o
::r r:/) ~
Pol ~
"0 > BEAUFORT WEST 32'
~., (') 32' IJs /-n SALDANHA' Ventersdorp-S' \D T BAY00 Supergroupa 0 100 0 100 200 400km'-' I I I I I I I I ~PORTELIZABETH I Jl Distribution J
-Q..n~o' ·34' 22' 24' 26' 28' 30' 32' 34: ~'l
::l I I I I I I I
I
tv
o,
::J VOLCANICROCKS SlD~ciJ~RY TECTONICSo FORMATION
a: 'n Fe!~~;•.,I'nl~rme- I~afic IPyroclastic Rudiles Are nit e s IT~po- Gra - rosiona
Cl IForp"", dia te a rocks Igr, ly bens Uncon-
Porphyry (ormily
ALLANRIDGE
w--'
Z
o,
BOTHAVILLE _mnl
1---I-R-,E-TG-A-T---I----jI---l-,.;,M=@;-;rII--:"A:-+---,.~';,---'-~I--I-f:~~1-6-:\' .
aC:l MAKWASSIE
w o li, 0 % m:
m
I-
:5 GOEDGENOEG
o, ~:
KAMEELDOORNS
Figure 1.2 Stratigraphic subdivision, lithologies and associated tectonics of the
Ventersdorp Supergroup (after Van der Westhuizen et al.,1991).
The strati graphic setting of the Ventersdorp .Supergroup is of particular interest to;,~hc
exploration geologist since it directly overlies the gold-bearing Witwatersrand strata.
Despite being a formation of considerable thickness and diversity of material, no
economic mineralisation has been found within the Ventersdorp Supergroup.
1.2 Study Area.
The study area (Figure 1.3) is located between the towns of Allanridge and Bothaville,
in the Free State. Core from 20 holes was examined, covering an area of
approximately 127 krrr',
Chapter 1 - Introduction - 3
Figure 1.3 Map of the study area indicating borehole localities and position of
structural sections (Figures 2.23a and b) (key on following page).
Chapter 1 - Introduction - 4
LEGEND
___.M_ajor Roads lw db+ ;q fW_tw AAi<!
Minor Roads
Railways
Rivers ,r-'\...._/.r-
Farm Boundaries ~
Borehole Localities NVT1 •
(Key to map on previous page)
Borehole core sections and their corresponding logs were made available by the
Target and Sun Divisions of Anglovaal Ltd. at both their Allanridge and
Hartebeesfontein establishments. The selection of. individual boreholes for
examination was made on the basis of the degree of development of the Rietgat
Formation contained therein, as observed in the Anglovaal logs. Additional logs of
20 other Anglovaal boreholes (the core of which was not examined during the
course of this study) were provided in order to assist the process. of lateral
correlation. While the Rietgat Formation remains the main focus of the present
study, logging and sampling of Klipriviersberg and Allanridge lavas was also
undertaken in order to monitor the geoehemical evolution both prior and subsequent
to the emplacement of the Rietgat Formation. A list of boreholes which were re-
logged and sampled during the course of this study is presented in Table 1.1.
Explanation of sample and borehole nomenclature.
Chapter I - Introduction - 5
It is appropriate at this stage to provide an explanation of the system by which
boreholes and samples have been named and numbered, The alphabetic sample
prefix is an abbreviation of the farm name within which the borehole is situated. A
summary of all farm names relevant to this study is given in Table t .2./
Table 1.1 Location of Anglovaal boreholes investigated by the present .s.tudy.
Borehole I N-S* E-W* Acknowledged Geologist (!Logging) Date
OKL5 64,749.86 37,556.17 A. C. Owens 04-12-92
OKL6 65,861.00 38,581.07 G. W. Edwards 13-10-92
OKL8 64,410.00 39,140.00 J. Crozier (provisional logging only) 10-06-97
-
OKPI 57,678.8-0_--_-34-,6-39.09 J. Wiegand 09-04-86
ER02 68,117.04 38,938.71 A. C. Goldsmith - 22-03-93- .
ER03 68,145.00 38,041.00 O. M. Le Roux 02-04-93
ER04 68,043.31 38,535.88 G. W. Edwards 03-12-94
KFN2 60,450.13 39,902.46 J. Wiegand 13-10-85
LRP3 65,931.64 37,320.93 J. NicholIs 11-12-92
I
MAl 53,571.90 37,073.40 J. Wiegandl 03-12-85
MA2 , 51.887.1-0- 36,207.62 P. G. Norman -.. 23-06-89.
MALI I 61,063.10 36,425.00 IJ. Wie~~~d I .26~08·~8S-
I -
MAL4 I 63,513.16 39,256.55 IM. A. Van den Berg 23-06-89
NVTI 44,949.49 38,723:80 I t t
POEl I 67,571.00 38,789.00 IJ. NicholIs 15-03-93
S3 I 66,311.00 38,967.00 lA. C. Owens 21-11-92
I
S4 i 67,329.00 39,041.00 .o. M. Le Roux 12-02-93
SS II 65,876.57 / 39,257.62 iw. Marais 19-08-91
I
S6 ! 67,060.21 , 38,501.53 IN. Williams 10-02-93!
TNT2 ! 56,093.17 i 38,050.41 IF. Martens 01-10-90
* longitudinal and latitudinal co-ordinates.
t unavailable at time of writing.
Since many boreholes are generally sited on the same farm, the alphabetic prefix is
followed by a further digit, which refers to the specific borehole. The final part of
the code, separated from the borehole location by a hyphen, concerns the individual
Chapter I - Introduction - 6
sample. These numbers are unique to each sample and increase with depth. For
example, a sample bearing the number 'DKL6-15' originates from borehole number
6 on the Dreyerskuil farm and is the is" sample from the surface.
Table 1.2 Summary of farm names and borehole abbreviations adopted by this
study.
Farm Name Abbreviation
Siberia S
Eldorado ERO
Paradise POE
Le Roex's Pan LRP
Oreyerskuil OKL
Mariasdal MAL
Kruidfontein KFN
Ooornknop OKP
Twistnet
I ~_
TNT
.. - _.-._-
Mara MA
INooitverwacht NVT
1.3 Research Objectives.
This project forms part of a greater study conducted in co-operation with Billiton
SA Ltd., the intentions of which have been to elucidate the geochemical
characteristics of extrusive igneous provinces. The primary aims of this study were:
Chapter I - Introduction - 7
• To establish a detailed stratigraphy for the Rietgat Formation, based on
geochemical analyses and field observations.
El To determine, by means of correlation between holes, the nature of any post or
syn-depositional crustal movements that may have taken place.
o To determine whether any stratigraphic units can be distinguished on the basis of
their geochemistry and/or mineralogy. If sb, whether these geochemically and/or
mineralogically defined units may be correlated between boreholes as well as at
remote localities.
e To develop a simple genetic model explaining the observed geochemical
variations and accounting for the emplacement of the Rietgat volcano-
sedimentary rocks.
1.41 Previous Research.
The Ventersdorp Supergroup has been the focus of much research, though only a
small amount of this work pertains to the Rietgat Formation. Although previous
work is alluded to throughout this study a briefliterature review is presented here.
1.4.1 Pioneering Studies.
Wyley (1859), Hatch (1903) and Corstorphine (1903, 1904, 1906) deserve credit for
their pioneering role in Ventersdorp exploration. Their work dealt mainly with
aspects of stratigraphy and lithologicical correlation. Nel (1927, 1935), Nel et al.,
Chapter 1 - Introduction - 8
(1935, 1939), Beetz (1937), Jacobson (1940), Matthyssen (1953), Pienaar (1956)
and Haughton (1969) should also be recognised for initiating research interest in the
Ventersdorp Supergroup.
1.4.2 Broader scale interpretation of the Ventersdorp Supergroup.
Perhaps the most comprehensive and widely acclaimed work regarding the
strati graphic subdivision of the Ventersdorp Supergroup is that of Winter (1976), a
publication which represented the culmination of a number of years research work at
the University of the Witwatersrand (Winter 1961, 1962, 1963, 1964, 1965, 1965b).
The recommendations of Winter's 1976 paper were subsequently adopted by SACS
(1980), an abridgement of which is presented in Figure 2.1.
1.4.3 Structure and Tectonics.
Tectonic development during Ventersdorp times has been discussed by Bickie and
Eriksson (1982), Schweitzer and Kroner (l 985), Burke et al. (1985, 1986), Winter
(1986, 1987), Stariistreet et al. (1986), Clendenin (1989), Clendenin et al. (1988a,
1988b, 1989) and McCarthy et al. (1990a). Most of these researchers concluded that
the Ventersdorp Supergroup formed as a result of rifting associated with the
collision of the Zimbabwe and Kaapvaal cratons. Visser and Grobler (1985) studied
the interplay between volcanic and sedimentary processes during Rietgat and
Bothaville times, while Meiritjes et al. (1989) discussed volcano-sedimentary
processes in terms of a regional structural model. Pienaar (1956), Visser (1957),
Crockett (1971) and Tyler (1979 proposed that large-scale faulting acted as a
conduit system for ascending magmas.
Chapter 1 - Introduction - 9
1.4.4 Gcochcmistry.
Geochemical investigations of the Ventersdorp lavas have been undertaken
thn;lUghout the area of the Witwatersrand basin by Palmer et al. (1986), Myers et al.
(1990), Linton (1992) and Linton and McCarthy (1993). Similar studies were also
carried out in the Western Transvaal: T. B. Bowen (1984), Schweitzer and Kroner
(1985), Bowen et al. (1986a, 1986b) and Crow and Condie (1988) studied the
geochemistry of the Ventersdorp Supergroup volcanic rocks and attempted to
constrain their tectonic setting by using conventional discrimination techniques.
With reference to trace element data, Myers et al. (1987) argued that the Kaapvaal
volcanic pile is tholeiitic and of lithospheric origin; McIver el al. (1982) and
Grobler et al. (1986) proposed a komatiitic affinity for the same suite of rocks.
1.4.5 Mineral Paragenesis-
According to Labuschagne (1974), the mineral assemblages encountered throughout
the sequence are representative of a quartz-albite-epidotc-biotite sub-facies of
metamorphism. Petrographic investigation by Comell (1977, 1978) confirmed this
feature. M. P. Bowen (1984) also recognised lower greenschist facies metamorphic
assemblages throughout the Ventersdorp Supergroup.
1.S Analytical Methods.
Major oxide and trace element concentrations were determined by means of XRF at
University of the Free State and REE's by ICP-MS at the University of Cape Town.
For a comprehensive listing of ail XRF analyses undertaken during the course of
this study, the reader is referred to Appendix 3. It is important to note that the
Chapter I - [ntroduction - 10
aforementioned data are raw and that normalisation to 100 wt.% and the omission of
highly altered samples (based on variably high LOI's) was undertaken prior to
inclusion in the discrimination diagrams in this study. An explanation of analytical
procedures is given in Appendix 1.
Chapter 1 - Introduction - Il
CHAPTER 2: THE STRATIGRAIPHY OF THE RIETGAT FORMATION.
2.1 Introduction.
Although previous subdivisions of the Rietgat Formation, as seen between Bothaville
and Allanridge have been considered here, greater emphasis has been placed on the
synthesis of a revised system of division based on the findings of the current study
(Figure 2.4). The findings of this chapter have been presented in the form of borehole
logs (Figures 2.26-2.38). It should be noted that the geochemical profiles, which have
been included in these sections, are of little consequence to the current chapter. For an
interpretation of downhole variations in geochemistry, the reader is referred to
Chapters 4 and 5.
2.2 Previous Sub-divisions and Stratigraphy of the Rietgat Formation.
Winter (1976) observed a group of porphyritic lavas near the base of the Rietgat
Formation. distinguishable from the underlying Makwassie Formation porphyries only
by the fact that they were non-acidic. Winter named this unit the Garfield Member,
suggesting that these lavas may be contemporaneous with other quartz porphyries
generally occurring in the lower portion of the Rietgat. Away from the Rietgat type
section of Winter (1976), (Figure 2.1), the member may contain non-porphyritic and
sedimentary intercalations. Winter furthermore argued that the Garfield Member may
also become a member of the Makwassie Formation where it is overlain by quartz
. porphyry tlows. Indeed, it has been suggested by Winter (1976) that in certain places
Chapter - 2 - Stratigraphy - 12
part or all of the Rietgat Formation may be contemporaneous with the Makwassie
Formation.
UNIT STRATQTYPE
PLATBERG GROUP
RIETGAT FORMATION
FLOWS
r-:"":-:-I.-","-.-.-cn>...,-::'-y ""fiow::::•-•:----'r;;-."'"'I.-pa-r-p""'be-ooc-ry-.-"'-'
to 3 mm. Amyploldlll.
Q\L&rt.tIt.e. (rCy. cberty.
La ... n..... ,"",.~rey. r.lly. d..... ly o.mygda
II loldal tops; bleacbed. turl "row .
.."
24 Lan. rreeD-erey amygdalok1al, deur lo (1J)e-grateed, La~ (b.alcedooyWC11111011".
Nume roWl thLD. amygd.alo1dal nows. oC
Quartz. (blorl,., and eêatcedcoy.
l.t.M.ly amygdatoldot lava.
"'T Numerou.a amytdaloldd flows. Tl4y felspar
crywula l4 ~Q-,re1 m.tru.
Amyptol.ut ",".o-grey porpbyrltlc;
Gre)"Wackc. gndu to coag.lomcf'2.tc',pebbtes to
.. 7$ mm ol"n. cbe et, abAte, quartzite IUd,' QU3rtl. s..u.t cbert bed.
GARFtnO MEMBER
Flows. r;-ic to d.u\ gt"C"Cn-grey porphyrltlc,
felspar ~DOC'ry5t.s lo 5 mm. Brece tated now
topo.
Va.rtOU8 thlc~ae. ol a.mygd.alokbJ tcoe ,
Some now, de ea e , ot.bcn medium cryslaltl.De
.od d Laba.o le.
Figure 2.1 Type section borehole RG 1. for the Rietgat Formation, as envisaged by
Winter (1976).
With regard to the upper portion of the Rietgat Formation, Winter (1976) concluded
that sediments become dominant over lavas in terms of their abundance. Although of
considerable thickness, these sediments never contain the large quantities of coarse
clastic debris characteristic of the Kameeldooms Formation (Figure 1.2). Winter
(1963, 1976) and Buck (1980) observed algal stromatolites and lacustrine limestones,
which manifest themselves in the upper portion of the Rietgat Formation. Karpeta
Chapter - 2 - Stratigraphy - . 13
(1989) noted that in the Hartebeestfontein area, the Rietgat Formation contains
stromatolites and cherts, which he proposed formed part of a magadiitic playa lake
system.
While working in the Welkom area of the Free State, Buck (1980) noted that certain
fault-controlled basins did not contain any of the lavas characteristic of the Platberg
Group further to the north. The absence of such lavas reveals that sedimentation was
continuous in large areas that were not affected by volcanism. These observations
prompted Buck (1980) to propose the localised addition of a new formation to the
Ventersdorp Supergroup: this, the Klippan Formation, is a lithostratigraphic
equivalent of the Kameeldoorns and Rietgat Formations as seen in the northern Free
State. According to Buck (1980), the Klippan Formation comprises two fining-upward
sequences, to which the names Video and Dirksburg members have been applied.
',.-:-;
Note on the correlation o(the Platberg Group at other localities.
The Platberg Group volcano-sedimentary successions may also 'be recognised at
localities away from their type area, an example of such an occurrence being the,
Sodium Group at T'Kuip (Figure 2.2). A consistent resemblance in the lithology,
stratigraphy and inferred conditions of deposition may be seen between the Sodium
Group and the Platberg Group in the Bothaville area, as classified by Winter in 1976
(SACS, 1980). Furthermore, Grobler et al. (1975) were able to distinguish the entire
Platberg Group in a series of boreholes between Tuang and Britstown in the Northern
Cape province. Although the South African Committee for Stratigraphy has since
accepted these correlations to be valid, a geochernical appraisal of the Sodium and '
Chapter - 2 - Stratigraphy - 14
Platberg Groups has been incorporated at a later stage in the present study, in order to
confirm the macroscopic observations of previous workers.
.<:'>
VILETS I(VIL ~
1')8 ~ :.~
t
§ OM,.", .... '0_AllanridQ'
~~ D Voleon/Cbt.ccia
~ 8011'10";1'-
I
. Lt"' .. of .'romolol/tic Ibn.. ton./Ch.rt
Malic loooG
~~ lt"•••of OnOIl
~ •T C:lip OUOt'tl Porphyry ~ 0\10"1 porph.fY
j 0ftQ." Ri." Arkou d_=l Ct(lflit,·,p.bbl. CO"<llom"o, •• or~o.;c (I"toncll./tu:h""
Figure 2.2 Type area of the Sodium Group, T'Kuip (after Grobler and Emslie,
1975, 1976 and SACS, 1980)
2.3 Geochronology.
Apart from constraining the age of the Ventersdorp Supergroup geochronological
work is of considerable importance in that it provides a minimum age for the
underlying Witwatersrand Supergroup. As the worlds largest known gold deposit, the
Witwatersrand Supergroup is the subject of many genetic models, essential to which
are accurate age constraints. Since the sediments of the Witwatersrand basin do not
Chapter - 2 - Stratigraphy - 15
lend themselves to age-dating (Armstrong et al., 1986, 1991), it is evident that
geochronologists must instead derive age-constraints from adjacent formations.
Much controversy exists regarding the precise age of the Ventersdorp Supergroup. A
variety of geochronological techniques have been applied in an attempt to solve this
problem, yielding a range in dates from a number of localities. Linton (1992) noted
that these dates fall into two ranges, a younger set, ranging from 2140 Ma to 2470
Ma and an older set ranging from 2630 Ma to 2730 Ma. A summary of such age
determinations for the Ventersdorp Supergroup is presented in Tables 2.1 and 2.2
(adapted from Linton, 1992), accompanied by references for each age, as well as the
geochronological method used.
It may be seen that the majority of the younger ages shown in Tables 2.1 and 2.2
were determined using whole-rock methods (Rb-Sr and Pb-Pb). The preponderance
of older ages were, however, determined by U-Pb or Pb-Pb techniques performed en
individual zircon grains.
The most recent and reliable zircon ages of the Orkney, Goedgenoeg, Makwassie and
Allanridge Formations (Figure 1.2) in the Western Transvaal (as determined by
Armstrong et al., 1991) are 2714 Ma, 2710 Ma, 2709 Ma and 2700 Ma, respectively.
These dates were ascertained by U-Pb ion microprobe analysis and have been
adopted as standards in the present study. It follows, therefore, that the Ventersdorp
Supergroup was erupted over a period of 14 Ma and more specifically, that the
Rietgat Formation was erupted in 9 Ma - or possibly less - between 2709 Ma and
2700 Ma.
Chapter - 2 - Stratigraphy - 16
Table 2.1 Ages for the Ventersdorp Supergroup in the 2140-2470 Ma range.
"
METHOD LOCATION AGF {Ma) REF.
Rb-Sr (whole rock) Klerksdorp (Makwassie Formation) 2140 ± 260 I
Rb-Sr (whole rock) Lobatse (Quartz Porphyry) 2200 ± 100 2
Rb-Sr (whole rock) Lobatse (Quartz Porphyry) 2215 ± 100 2
Rb-Sr (whole rock) Lobatse (Quartz Porphyry) 2230 ± 120 2
U-Pb (zircon) 26°52'S, 26°39'E (Ventersdorp Lava) 2238± 100 3
U-Pb (zircon) 26°52'S, 26°39'E (Ventersdorp Lava) 2245 ± 90 3
U-Pb (zircon) 26°52'S, 26°39'E (Ventersdorp Lava) 2300 ± 100 4
Pb-Pb (whole rock) Klerksdorp (Makwassie Formation) 2350± 170 I
Pb-Pb (whole rock) Mondeor, Jhb (Klipriviersberg Group) 2360 ± 335 I
Pb-Pb (whole rock) Mondeor, Jhb (Klipriviersberg Group) 2368 ± 249 6
i
Pb-Pb (whole rock) Eikenhof, Jhb (Klipriviersberg Group) 2370 ± 70 I
Pb-Pb (zircon) Stella, Vryburg (ZoetliefGroup) 2470 ± 100 3
U-Pb (apatite) Taung (ZoetliefGroup) 2471 ± 100 5
Table 2.2 Ages for the Ventersdorp Supergroup in the 2630-2700 Ma Range. .'i.'
METHOD LOCATION AGE (Ma) REF.
Pb-Pb (zircon) Lobatse (Felsite) 2630 ± 100 3
U-Pb (zircon) Lobatse (Quartz Porphyry) 2630 ± 100 3
U-Pb (zircon) Goedehoop (ZoetliefGroup) 2634 ± 100 5
Pb-Pb (whole rock) Klerksdorp (Makwassie Formation) 2638± 105 5
U-Pb (zircon) Lobatse (Quartz Porphyry) 2640 ± 100 3
U-Pb (zircon) Klerksdorp (Makwassie Formation) 2643 ± 80 5
U-Pb (zircon) Klerksdorp (Makwassie Formation) 2693 ± 60 I
Rb-Sr (whole rock) Lobatse (Quartz Porphyry) 2695 ± 125 2
U-Pb (zircon) Klerksdorp (Makwassie Formation) 2699 ± 18 I
Chapter - 2 - Stratigraphy - 17
REFERENCES USED IN THE COMPILATION OF TABLES 2.1 AND 2.2.
1. Armstrong et al. (1986)
2. Burger and Coertze (1973)
3. Van Niekerk (1968)
4. Van Niekerk and Burger (1964)
5. Van Niekerk and Burger (1968)
6. Walraven et al. (1983)
Armstrong et al. (1986) and Walraven et al. (1983) have argued that Rb-Sr age
determination techniques may be prone to giving false results, probably a
consequence of low-grade metamorphism of the rocks in question, which has
affected the Rb-Sr isotope systematics. In short, Armstrong et al. (1986) have
proposed that older age determinations are representative of the true age of the lavas
and that any younger dates merely represent a subsequent metasomatic event, which
'reset" certain isotope systems.
Nelson et al. (1992) published Sm-Nd isotope data for the Alberton and Lower
Orkney Formations, which indicated dates approximately 600 Ma older than those
derived by U-Pb zircon results. Nelson et al. (1992) have suggested that their Sm-Nd
data may either represent a lithospheric fractionation event, or indeed, the mixing of
more than one mantle source.
Chapter - 2 .: Stratigraphy - 18
2.4 The Rietgat Formation in the Study Area.
The Rietgat Formation is only encountered at depth in the Allanridge-Bothaville area,
and therefore all of the observations presented in this study are based on the
examination of borehole core. The locations of the boreholes in question are shown on
Figure 1.3. In the majority of bore hole sections, the Rietgat Formation unconformably
overlies the Makwassie Formation. In certain sections, however, the Makwassie,
Goedgenoeg and Kameeldoorns Formations are omitted from the sequence, bringing
. the Rietgat and Klipriviersberg Formations .into contact with one another. Examples of
this relationship include boreholes AATl, DKLl and S2 (Kershaw, pers. com., 1997).
The Rietgat Formation is unconformably overlain by the Bothaville and Allanridge·
Formations and increases substantially in thickness from both south to north and from
east to west.
Note regarding the approach adopted by this study.
Due to the fact that many previous studies of the Ventersdorp Supergroup have been.
undertaken with considerable breadth, it is possible that sub-divisions within smaller
formations (such as the Rietgat) may have been overlooked. The remainder of this
investigation attempts to sub-divide the Rietgat Formation on the basis of both
lithological and geochemical variation.
Similar studies of other formations have in the past followed a convention whereby the
petrography of the rocks in question is addressed prior to their geochemistry. Due
to the fact that petrography alone is insufficient to constrain strati graphic sub-
divisions, the bulk of such demarcations presented in this study are based on
Chapter - 2 - Stratigraphy - 19
criteria. It is therefore necessary for the purposes of continuity to include a brief note
on the geochemical subdivisions used in this study. A more comprehensive
geochemical appraisal of the Rietgat Formation stratigraphy is presented in Chapter 4.
2.5 Basic geochemical subdivision of the Rietgat Formatien
A number of bivariate plots utilising a range of immobile elements (P, Ti, Zr, Y, V)
were constructed in order to detect clustering in the data. It was found that a plot of Zr
versus P205 (Figure 2.3) best illustrates the clustering of data points with respect to
distinct geochemical units. In addition to these geochemically-constrained sub-
divisions, upper and lower sedimentary horizons were identified by visual means.
1.15
El Unit 1
1.05 .....~ :
.- : : ~ ':: :. .
I:> Unit 2 :0 ·· .. ..· . .
0 Unit 3 . . · . .~ : .
0.95 .. D Unit 4 ..... ; -., -: ; -: ~ : °0-·····
o Unit 5 : 0 ~ : : 0
;R : 0 <:Jr>: 0 0 0 ,<0 .l...-._----,. _ ___.J 0 0 . 0 . O· .: :
0
:ë 0.85 ............ : ~.. :~'o ().0. ?O··o·········:··········· .: : ~ .
Ol ~<:SO 6 ,,-0 0: : 0 :.0 0 :
's(jj '«5R 0.0 v ., .0.75 ........... ~ O~<}:J 0~~~ o· + 0 • Q]'" .·o~··~·otP' .~.tfb····· .. j ~ .lf)
0
N
Q_ : 0 : : 0'88,~~ 0 0 ctJFpoéP : . :
· . .00 0 ~ 00. : :
0.65 ............: ~ o' c':'" '6" -o- -gcP ..dj : ~ : .
:. : 0 00 0 0-. . .
: ; 0:' O.e~ort:o 0 ~ ~ ~
0.55 •..•....•... :•..•.•••• .Q ~ ...••••• 0 : <jf; .oQq.o : ; ~ . I· o . '0 OG
:· :. :. êO :
·· .
.
. .. .. I
0.45 L-....._~ ........~..~. ~...._._. _~~_._' ~~~__;',-----_~.._;_~~~_;_~~~_;_~~~_J
160 200 240 280 320 360 400 440 480
Zr (ppm)
Figure 2.3 Zr vs P20S discrimination diagram for the Rietgat Formation.
Chapter - 2 - Stratigraphy - 20
A summary of all of the units recognised by the current study are presented in Figure
2.4, in order of increasing stratigraphic height.
"
UNIT REFERENCE [NFORMAIL DESCRIPTIVE NAME
USH Upper Sedimentary Horizon
5 Upper Rietgat Member - Amygdaloidal
4 Upper Rietgat Member - Non-amygdaloidal
3 Central Rietgat Member
2 Upper Garfield Porphyry
1 Lower Garfield Porphyry
LSH Lower Sedimentary Horizon
t
I
Figure 2.4 Summary of stratigraphic units recognised in the present study.
In addition to the sub-divisions outlined· in Figure 2.4, coarse-grained sheeted
intrusives of basaltic composition were encountered, particularly in section DKPI
(Figure 2.30). It is proposed that this material represents a feeder system for later
extrusive formations, possibly the Allanridge Formation, but more probably the Karoo
,lavas given the basic affinity of the rocks in question. Tuffaceous intercalations were
also identified at many 'different strati graphic heights throughout the study area. Due
to the extreme range in composition of such material, it was not possible to include
the tuffs in the geochemical classification scheme.
Chapter - 2 - Stratigraphy - 21
2.6 Petrography of the Rietgat Formation.
Introductorv Note 011 AIteration.
The primary mineralogy of the lavas (and to a certain extent the igneous textures) have
undergone severe alteration as a result of metasomatism and metamorphism. A mineral
assemblage comprising quartz + chlorite (ferroan clinochlore) + albite ± epidote ±
actinolite ± muscovite ± biotite was identified by XRD and optical mineralogical
studies. This assemblage is indicative of lower greenschist facies metamorphism
(Winkier, 1974) and has also been identified by other studies of the Ventersdorp
Supergroup (ComeIl, 1978; Tyler, 1979; Schweitzer and Kroner, 1985; Crow and
Condie, 1988; Grobler et al., 1989; Meintjes, 1998). This paragenesis manifests itself
principally as extensive silicification and chloritisation, in addition. to varying degrees of
epidotization.
Quartz veins and vugs, as well as amygdalc fillings, attest to at least one fluid event:
the results of thermometric analysis of inclusions contained therein are presented in
section 3.7.1. Alteration of the Rietgat Formation in the study area may be clearly seen
on a.macroscopic scale in the form of bleached zones - particularly in close proximity
to faults or other fissures. These zones (which should not be confused with weathering
horizons) are characterised by higher facies alteration assemblages than adjacent rocks,
typically displaying higher degrees of silicification and epidotisation. Figure 2.5
illustrates a mottled. sample, which has undergone a moderate degree of fluid
alteration: a more advanced degree of alteration may be seen in Figure 2.6, which
depicts an epidotised horizon.
. Chapter - 2 - Stratigraphy - 22
2.6.1 Lithological and mineralogical observations.
The following paragraphs aim to provide a lithological and mineralogical overview of
the Rietgat Formation according to the units described in the foregoing sections.
2.6.1.1 Lower Sedimentary Horizon (LSH).
Distribution and disposition.
The LSH is restricted to relatively few borehole sections, principally S6, S4 and
DKL6 (Figures 2.35,2,37 and 2.38 respectively) in the south and section NVTI in the
north of the study area (Figure 2.26). As may be seen from Table 2.3, the LSH. ranges
between 5.9 and 14.5m in thickness - 11.73m on average, compared to nearly 35m for
the USH.
The LSI-I comprises a series of shales and quartzwackes in association with occasional li
diamictites (Figure 2.7). Some very fine, layered material (Figure 2.8), possibly of
pyroclastic origin was also recognised in this unit. Although grain-size ranges in
diameter between 0.5 and 3.0cm in the LSH, rudaceous examples are comparatively
rare in this unit. In terms of its colour, the horizon is characteristically grey, ranging
from darker shades for the finer sediments, to lighter hues for the coarser material.
Where identifiable, lithic clasts generally consist of detrital lava, the origin of which
could not be constrained further than the Ventersdorp Supergroup. Otherwise, clasts
comprise quartz (>70%), mica and occasional feldspars. Fining-upward sequences are
common in the LSH and may be readily detected by the colour variation between their
Chapter - 2 - Stratigraphy - 23
fine and coarse components (Figure 3.2). Cross-bedding was also noted on a
centimetre scale (Figure 2.9).
Table 2.3 Summary of the total unit and individual flow thicknesses for the-Rietgat
Formation
Total Thickness of Entire Unit Thickness of Individual FIO't¥s
(metres) (metres)
Mean Min. Max. Mean Mill. Max.
Upper 34.76 14.91 49.10 - - -
Sediment
Unit 5 41.03 63.00 105.00 5.77 0.03 79.88
Unit 4 28.44 6.00 78.00 3.12 0.15 23.22
Unit3 132.30 9.80 348.00 8.39 0.43 64.95 i
Unit .2 49.53 14.90 116.70 21.57 9.95 53.39
Unit 1 66.08 9.80 134.00 13.78 0.10 46.12
Lower 11.73 5.90 14.50 - - - i
.Sediment :
A degree of silicification is evident in the LSH, as well as calcification and the
concentration of secondary metallic sulphides. Alteration, although present, is less
extreme than that seen in the overlying lavas: a greenschist facies assemblage is not
immediately evident and little chloritisation may be seen. It is proposed that prior to
alteration. the sediments were relatively mature with respect to their mineralogy,
therefore the subsequent alteration product is relatively unchanged.
Chapter - 2 - Stratigraphy - 24
Scale
o 2 4 6 8 10
Centimetres
Figure 2.5 Non-amygdaloidal example of Unit 3 lava, displaying mottled alteration.
It is proposed that this 'mottled facies' is the product of varying degrees of fluid
alteration (sample NVTl-41).
Figure 2.6 Sparsely amygdaloidal example of Unit 3 lava, displaying elevated
levels of epidotisation, as is indicated by the yellow-green coloration of the specimen
(sample NVTl-31a).
Chapter - 2 - Stratigraphy - 25
o 2 4 6 8 10
Centimetres
Figure 2.7 Clast-supported diamictite (USH), possibly generated as a result of fault
scarp denudation, or as a flood deposit on a palaeolandsurface (sample S6-6).
o 2 4 6 8 10·I
Centimetres
Figure 2.8 Very finely layered cryptocrystalline material of possible pyroclastic or
exhalitive origin - sinter deposit? (sample ZTDI-49).
Chapter - 2 - Stratigraphy - 26
In the case of bore holes S6, NVTI and S4 (Figures 2.35, 2.36 and 2.37), the LSH rests
as a sub-conformable surficial deposit on the Makwassie Formation.
Where section DKL6 is concerned (Figure 2.38), the Makwassie and Goedgenoeg
Formations (Figure 1.3) are absent from the succession. As a result, the LSH rests
unconformably. on the sediments of the Kameeldooms Formation. The LSH, where
present, is overlain by Unit 1 (section NVT1, Figure 2.26), Unit 3 (sections S4 and
DKL6; Figures 2.37 and 2.38 respectively) and Unit 5 (section S6, Figure 2.35): in the
former two cases a localised extrusive hiatus is indicated.
2.6.JL.2 Unit I (Lower Garfield Member)
Distribution and disposition.
Unit 1 was observed in all borehole sections north of KFN2 (Figures 1.3 2.28) and is
thickest in borehole MALl (Figure 2.32). The total thickness of the unit ranges from
9.8 to 134m (Table 2.3), comprising individual flows of between 0.1 and 46.12m.
Unit 1 is characteristically porphyritic, greenish-grey in colour, containing blebby
chlorite and sub- to euhedral phenocrysts of plagioclase feldspar, principally of albitic
composition (according to XRD, see Chapter 3). The aforementioned porphyries are at
their coarsest towards flow centres containing plagioclase phenocrysts of up to 4mm
length. It was also noted that Unit 1 coarsens considerably towards its base, where the
plagioclase phenocrysts become progressively larger and more euhedral (Figure 2.10).
Geochemistry aside, the porphyries of Unit 1 may be distinguished from those of Unit
2 on the grounds that they are consistently more porphyritic. Some aphanitic flow
units were also seen, as were occasional amygdaloidal horizons.
Chapter - 2 - Stratigraphy - 27
o 2 4 6 8 10
Centimetres
Figure 2.9 Small-scale cross-bedding in the LSH, indicating the migration of small-
scale sedimentary bedforms. The intercalated quartz material (A) is possibly derived
by means of secondary processes (sample ZTD 1-17).
Scale
o 2 4 6 8
Centimetres
Figure 2.10 Medium-grained porphyritic lava characteristic of Unit 1. Subhedral to
euhedral albite phenocrysts are set in a quartzJchlorite groundmass (sample KFN2-24)
Chapter - 2 - Stratigraphy - 28
It is proposed for the purposes of this study that Units 1 and 2 are correlates of the
Garfield Member as described by Winter (1976). Assuming that this is the case, Units
I and 2 have been tentatively named the 'Lower' and 'Upper' Garfield Members
respectively (the use of the distinction 'Member' being entirely informal in this case).
Geochemical evidence to substantiate this suggestion will be given in Chapter 4.
Sedimentary intercalations.
Diamictite intercalations.Isection TNT2, Figure 2.29) and breccia horizons may also
be seen On a very minor scale in Unit 1. No lateral correlation between boreholes was
possible where this material was concerned due to the localised nature of its
occurrence. The clastic component of these sediments is of local provenance (i.e, of
Unit 1 porphyry), suggesting that a minimal degree of transport was involved. The
.textural immaturity of these sediments further supports the theory that very little
transportation has taken place. A minor relocation of surficial detritus, itself the
product of weathering, is envisaged as the mechanism of sedimentation ..
The matrix of the breccias comprises grits and dark mud, which are presumed to have
been derived from the same source as the clastic material. A high degree of
calcification and to a lesser extent silicification and chloritisation may be seen, which
are likely to be products of either diagenetic or greenschist metamorphic processes.
As far as inferences based on the presence of sedimentary intercalations are
concerned, it is self-evident that some form of sub-aerial process must have prevailed.
This could have been contemporaneous with lava extrusion, sedimentation having
taken place on a palaeohigh, while extrusive activity continued in outlying areas.
Chapter - 2 - Stratigraphy - 29
Alternatively a complete break in extrusion may have occurred, during which surface
processes dominated. Whatever the case, the duration was sufficient to give rise to the
denudation of source areas and the deposition of clastic sediments.
Interred pseudotachylite in Unit J .
..Other notable features in Unit 1 include what has, with caution, been described as a
pseudotachylite'. Killick et al. (1986) identified similar material at the VCR-
Klipriviersberg interface, the origins of which they attributed to tectonism. Figure 2.11
illustrates a well-developed example of this material, which may be found in section
NVTl (Figure 2.24). Closer examination of the pseudotachylite revealed that the
constituent clasts contain very fine-grained plagioclase phenocrysts, It is likely,
therefore, that the clastic component of the pseudotachylite was derived from the
finer-grained porphyries of Unit 2.:
Another feature of the 'clasts is their relatively high metallic sulphide content,
principally accounted for by pyrrhotite. The sulphides appear to be restricted' to the
clasts only and do not manifest themselves in the matrix. This may be a function of
parent rock composition, or due to the fact that later fluid-bound sulphides were not
compatible in matrix phases.
The pseudotachylite is clast-supported and bound by a relatively hard, dense, black
aphyric matrix, which is featureless in hand specimen. Greater mention will be made
2 Due to the tentative nature of this description, the definition of a pseudotachylite, according to Bates
and Jackson "(1980) has been included: 'Pseudotachylite: a dense rock produced in the compression
and shear associated with intense fault movement, involving extreme mylonitisation and/or partial
melting. Similar rocks. such as the Sudbury breccias, contain shock-metamorphic effects and may be
injection breccias in fractures formed during meteorite impact '.
Chapter - 2 - Stratigraphy - 30
of the petrography and optical characteristics of both the matrix and clastic materials
in Chapter 3.
The precise juxtaposition of the pseudotachylite to the remainder of Unit (and
indeed the rest of the Rietgat Formation) is somewhat difficult to infer, since
observations are based on one occurrence only. Assuming that this rock type is indeed
a pseudotachylite and that it is fault-derived, geophysical and/or structural data for the
area (unavailable at the time of writing) would facilitate agreater understanding of its
disposition and mode of emplacement.
Relationship to other units.
Wherever the LSH is absent from the stratigraphy, Unit 1 comes into contact with the
underlying Makwassie Formation. No strong evidence to suggest that erosion has
. taken place prior to the emplacement of Unit 1 was detected. However, the presence
of the LSH is probably indicative of a brief time lag between the extrusion ofthe
Makwassie and Rietgat Formations. This is a.contentious theory, since it is possible
that the Makwassie Formation and lower flows of the Rietgat Formations are
contemporaneous (Winter, 1976).
Unit 2, where present, overlies Unitl with conformity; it is possible that the former is
a sub-facies of the latter. In the majority of sections, however, Unit 2 is absent; in such
cases, Unit 3 overlies Unit 1 conformably - further evidence to support the theory that
Unit 2 is indeed a sub-facies of Unit 1.
Chapter - 2 - Stratigraphy - 3 I
2.6.1.3 Unit 2 (Upper Garfield Member).
Distribution and disposition.
This unit is only present in the northernmost region of the study area and may be seen
in boreholes NVTI, OKPl and MA2 (Figures 2.26, 2.30 and 2.31 respectively).
Although geochemically and visually discrete, Unit 2 only appears to occur in
association with Unit 1 (and only then when the latter is at its most developed) and is
never encountered in isolation.
Unit 2 may be recognised macroscopically by its very finely porphyritic appearance as
well as the presence of blebby chlorite. Subhedral phenocrysts of quartz and feldspar
may be identified in a heavily chloritised sub-morphous groundmass. In places the
phenocrysts are small «I mm), though due to the fact that they are still relatively large
in comparison to the groundmass, the term 'porphyry' has nonetheless .been deemed
appropriate.
In terms of its total thickness, Unit 4 ranges between 14.9 and 116.7m (Table 2.3) ..
Table 2.3 also illustrates how the individual flows comprising Unit 2 are of greater
thickness than those of the remaining Units 1, 3, 4 and 5, ranging between 9.95 and
53.3901. This could be due to the fact that Unit 2 is only associated with the best
developed volcanic sequences in the study area.
The degree to which Unit 2 has been altered is somewhat less than Units 3-5: no
bleached or mottled horizons are identified in the unit, possibly due to a more
Chapter - 2 - Stratigraphy - 32
restricted fluid throughput or perhaps due to the fact that the porphyries are less
susceptible to alteration.
Pillow lavas.
Pillow lavas were encountered towards the base of Unit 2 in borehole NVTl (Figures
2.12, 2.13 and 2.26). The pillow structures themselves are intensely arnygdaloidal and
display severe alteration. The presence of shale and sulphide fillings between the
pillows, as well as an overlying shaly sequence of over 40m in thickness, is indicative
of a calm euxinic deep-water facies. There is no reason to presume that there was any
break in sedimentation during the emplacement of the pillow lavas.
Relationship to other units.
Allusion has been made to the possibility that Unit 2 is a sub-facies of Unit 1. Hence,
where present, Unit 2 will, by virtue of this association, be underlain by or intercalated
with Unit 1. It is argued in subsequent chapters that Unit 2 could represent a localised,
contemporaneous geochemical variety of Unit 1. Alternatively, Unit 2 could be a late-
stage derivative of the original Unit 1 composition, in which case the two units would
not necessarily need to be contemporaneous. Regardless of which of the above models
one subscribes to, Unit 2 rests upon Unit 1 with full conformity. Unit 2 is overlain
conformably by the lavas of Unit 3: there is no evidence to suggest that any prolonged
cessation of extrusion took place during the Unit 1-2 transition.
Chapter - 2 - Stratigraphy - 33
Scale
2 4 6 8 10
Centimetres
Figure 2.11 Possible pseudotachylite: highly angular phaneritic lava clasts set in a
dense melanocratic matrix. Relatively high metallic sulphide mineralisation
throughout (sample NVTl-50).
Figure 2.12 Amygdaloidal Unit 2 pillow lava. The pillows themselves exhibit
intense bleaching and silicification. Fine-grained sedimentary intercalations divide the
pillows (sample NVTl-46a).
Chapter - 2 - Stratigraphy - 34
Figure 2.13 Amygdaloidal Unit 2 pillow lavas displaying varying degrees of
bleaching, most notably at pillow margins. Sedimentary material fills interstices
(sample NVTl-45).
Scale
o 2 4 6 8 10
Centimetres
Figure 2.14 Typical example of monotonous Unit 3 lava. The lava is aphanitic,
heavily chloritised and its amygdale population ranges from sporadic occurrences to
dense discontinuous horizons (sample NVTl-23b).
Chapter - 2 - Stratigraphy - 35
2.6.1.4 Unit 3 (Central Rietgat Member).
Distribution and disposition.
Unit 3 is in evidence in the majority of the borehole sections in the study area. It is
generally well developed, with thicknesses for the entire member reaching nearly
350m. Individual flow thicknesses within Unit 3 are on average 8.39m, though they
range from 0.43m to nearly 65m (see Table 2.3). The unit is visually characterised by
its monotonous and sporadically amygdaloidal appearance (Figure 2.14). The
amygdales appear to occur at random throughout the unit, showing no affinity to flow
tops, rendering the identification of individual flow units·a somewhat complex process
and giving rise to both densely (Figure 2.15) and sparsely amygdaloidal horizons.
Unit 3 is extremely fine-grained and generally aphanitic with only the most developed
flows featuring porphyritic flow centres (Figure 2.16). In many of the sections, Unit 3
contains quartz veining and vugs up to 2cm in diameter.
Unit 3 shares many common characteristics with Units 4 and 5. Such features include
the widespread preponderance of chlorite and to a lesser extent chalcedony, as
amygdale filling materials. Furthermore, the greenish-grey colouration .of the lavas
closely resembles that of the overlying units. Unit 3 also contains a restricted number
of mottled (Figure 2.5), bleached and epidotised (Figure 2.6) horizons similar to those
encountered Units 4 and 5. A limited quantity of layered material was observed close
to the centre of Unit 3 in borehole NVTI. This horizon is geochemically and (with the
exception of the lack of amygdales) petrographically identical to the adjacent lavas. It
is proposed that the layered horizon represents what was originally a tuff of similar
Chapter - 2 - Stratigraphy - 36
Figure 2.15 Densely amygdaloidal Unit 3. The lava itself is aphanitic and heavily
chloritised/silicified and its amygdales contain zoned quartzlchlorite fillings (sample
NVTl-23a).
Scale
o 2 4 6 8 10
Centimetres
Figure 2.16 More thickly developed Unit 3 flows may exhibit a euhedral
plagioclase-porphyritic affinity. Otherwise, the sample is sporadically amygdaloidal
and displays chloritisation and silicification (sample NVTl-l Oa).
Chapter - 2 - Stratigraphy - 37
chemical composition to the lavas, which underwent the same alteration process as the
rest of the sequence. The banding is merely a textural relic of the primary rock.
Relationship to other units.
Unit 3 overlies Unit 2 with conformity, though where Unit 2 is absent from the series,
it conformably overlies Unit 1 instead. This may be attributed to petrogenetic reasons,
which are discussed in Chapter 5. The presence of bedded chert in section MA2
(Figure 2.31) is suggestive of a brief era during which warm, aqueous conditions
prevailed, probably on a palaeo-landsurface, which were conducive to the
precipitation of chert. The main importance of the cherts to this discussion is that their
presence signifies a break in volcanic activity. This is why the term 'close conformity'
has been used when describing the relationship between Units 2 and 3. This hiatus is
non-tectonic, non-erosive and is apparently non-depositional in all sections other than
MA2. In the opinion of the author, it is safer to assume that Units 1, 2 and 3 are
contiguous. As has previously been discussed, Unit 3 is conformably overlain by
Units 4 and 5.
2.6.1.5 Unit 4 (Upper Rietgat Member - Non-Amygdaloidal),
Distribution, disposition and relationship to other units.
Considerable reference has been made to Unit 4 in the preceding paragraphs, due to its
visual similarity to Unit 5, with which it is intercalated. In summary, Unit 4 comprises
a near-identical mineral assemblage to Unit 5, this comprising clinochlore, quartz,
muscovite and albite, as well as similar textures, colours, sediinentary intercalations
and ash horizons. The only visual contrast between Units 4 and 5 is the virtual
Chapter - 2 - Stratigraphy - 38
absence of amygdaloidal flow tops in the latter (Figure 2.17). Other notable features in
Unit 4 include epidotised and variolitic facies (sections S4 and DKL6; Figures 2.37
and 2.38 respectively) as well as occasional plagioclase porphyritic flow centres.
Unit 4 exhibits varying degrees of alteration, though overall to a moderate degree
only, since it rarely comes into contact with the overlying sediments and their
associated pervasive alluviation processes. This Unit occurs locally, being present in
only half of the sections examined. The range in total thickness for Unit 4 is between
6 and 78m, comprising individual flows of between 0.1 and 23m in thickness (Table
2.3). Unit 4 only occurs in conjunction with Unit 5 and never as a discrete entity and
overlies Unit 3 with conformity.
2.6.1.6 Unit 5 (Upper Rietgat Member - Amygdaloidal),
Distribution and disposilion
Unit 5 is recognised in every borehole in the study area, ranging in total thickness
from 65 to 105m. The unit comprises fine-grained greyish-green equigranular lavas,
the average flow thickness of which is 5.77m (Table 2.3). Many flows less than 10 cm
in thickness are seen, especially near the top of this unit. Interdigitation with Unit 4 -
from which it is geochemically distinct - is fairly common and may be seen in
borehole sections NlAI, KFN2, MALI, S4 and DKL6 (Figures 2.27, 2.28, 2.32, 2.37
and 2.38). As has been outlined, the only visual means by which Unit 5 may be
distinguished from Unit 4 is on the grounds of its amygdale content, the distribution of
which varies from confined flow-top occurrences, through dense amygdale clusters to
entirely amygdaloidal flow-units. The amygdales themselves range between 2 and
Chapter - 2 - Stratigraphy - 39
6mm in diameter, containing chlorite and/or chalcedony fillings, some of which
display concentric zonation.
Alteration.
As is the case with the majority of the Rietgat Formation lavas, Unit 5 has undergone
a high degree of fluid-related alteration. This has given rise to bleached horizons
(Figure 2.18), veins (Figure 2.19), veiniets, mottled facies and chalcedony vugs;
variolitic alteration may also be seen from place to place. Unit 5 displays the most
intense and macroscopically visible alteration in the Rietgat Formation, particularly in
its uppermost flows (Figure 2.20). Texturally, the unit is principally aphanitic, though
some of the thicker flows do contain some porphyritic plagiocJase, particularly
towards their flow-centres. It therefore follows that relatively massive flows (most
commonly found near the. base of the unit) show the greatest porphyritic affinity.
Sedimentary intercalations .
. .Besides its amygdaloidal lava component, Unit 5 also contains minor sedimentary
intercalations and tuff layers. These include quartzwackes (section KFN2 - Figure
2.28) and shales (section S4 - Figure 2.37). Occasional coarse clastic horizons may
also be seen which may represent brecciated flow-tops or alternatively in-situ
degradation of the lavas resulting from sub-aerial exposure.
Relationship to other units.
Earlier in this section, brief reference was made to the fact that Units 4 and 5
inderdigitate with one another in places. Where this is the case, no clear visible
demarcation may be made between the two units, with the exception of amygdale
Chapter - 2 - Stratigraphy - 40
Scale'
2 4 6 8
Centimetres
Figure 2.17 Although technically defined by its dearth of amygdales, Unit 4 does in
places exhibit sparse amygdaloidal tendencies. The amygdales typically contain quartz
and/or chlorite fillings (sample NVTl-27a).
Scale
o 2 4 6 8 10
Centimetres
Figure 2.18 Bleached, altered Unit 5 lava. Amygdales are abundant and contain
concentrically zoned quartzJchlorite fillings (sample ZTD 1-5).
Chapter - 2 - Stratigraphy - 41
Scale
o 2 4 6 8 10
Centimetres
Figure 2.19 Extreme alteration and bleaching in Unit 5. Primary igneous features -
such as amygdales - have been largely obliterated. Quartz veining is prominent
(sample NVTl-3).
Scale
o 2 4 6 8 10
Centimetres
Figure 2.20 Clear example of the intense alteration typical of the uppermost flow
units of Unit 5. The white phase of speckled appearance is leucoxcene - an alteration
product of sphene. Chlorite and quartz are also prominent alteration phases (sample
S6-1 ).
Chapter - 2 - Stratigraphy - 42
preponderance in Unit 5. The contrast between Units 4 and 5 is more readily
elucidated by geochemical means: it is probable that Units 4 and 5 are genetically
related and that the distinction between the two is a function of minor source
chemistry variation. This topic will be discussed in Chapter 5.
No erosional surfaces or other evidence for prolonged sub-aerial exposure (such as
bleached or weathered horizons) were identified in the upper portions of Unit 3. It is
therefore tentatively proposed that the lavas of Units 4 and 5 were extruded m
relatively rapid succession, leaving little scope for surface processes to operate.
2.6.1.7 Upper Sedimentary Horizon (lJSH).
Distribution and disposition.
The USH was encountered in the majority of the sections examined in the study area,
where it ranges in thickness between 14.91 and 49.1 m (see Table 2.3). The sediments
are typically quartz-rich and clast-supported and are bound by a fine-grained matrix of
calcite and opaque clay minerals. The clasts themselves consist of Ventersdorp lavas
and are seldom greater that 5mm in terms of their long-axis length. The presence of
occasional triple junctions between neighbouring quartz grains is attributed to either
metamorphic or diagenetic processes. Since most of the quartz grains have undergone
varying degrees of recrystallisation, It is extremely difficult to make inferences
regarding primary sedimentary textures. However, .the USH is texturally mature
(particularly in comparison to the LSH), the constituent clasts displaying a high degree
of rounding and sorting. Larger scale features such as fining upward sequences
Chapter - 2 - Stratigraphy - 43
(quartzwacke fining from grit up to sand), slump structures and cross-bedding are
clearly identifiable.
In addition to the aforementioned arenaceous quartz-rich sediments, the USH contains
a considerable amount of much darker argillaceous material in the form of mudstones,
shales and silt. These argillites may occur as distinct intercalations within more
arenaceous horizons, either as discontinuous flasers, partings, intraclastic
conglomerates or rip-up clasts. Generally, such argillites are between ~O.5 and lOcm
in thickness. Greater accumulations (> lm) of mudstones, shales and siltstones may
also occur as distinct laterally extensive horizons, where they are more, display
internal laminae and slumping and contain occasional sandy partings. The argillaceous
horizons may either grade progressively into arenites or there may instead be a definite
hiatus between these two facies. The precise mineralogy of the argillites is very
difficult to determine by macroscopic means, due to the very fine-grained nature of the
rocks. A degree of silicification and calcification was however noted.
Veins and stringers.
Confined stringer and vein networks were also encountered in the sediments. These
are almost invariably of quartz and are rarely developed beyond a few millimetres in
section.
Sulphides.
Low abundances of metallic sulphides (principally pyrite, pyrrhotite and chalcopyrite)
were identified in the USH. Two principal modes of sulphide occurrence were noted,
which are as follows:
Chapter - 2 - Stratigraphy - 44
• Granular detrital sulphides (Figure 2.21) occur in layers (2-5mm) which conform
perfectly to the sedimentary laminae. Macroscopic examination of the metallic
grains revealed a degree of rounding - suggestive of abrasion during sedimentary
transport processes.
e Figure 2.22 illustrates an example of 'framboidal' metallic sulphide mineralisation.
It is proposed that the pyrrhotite and pyrite in this style of mineralisation developed
in-situ around a nucleus, which may itself have been a detrital sulphide grain.
Further evidence to support this theory comes from the fact that the sedimentary
laminae adjacent to the mineralisation have been displaced by the growth of such
sulphides.
Relationship to other units.
In terms of its relationship to over- and underlying units, the USH overlies the lavas of
the Rietgat Formation with conformity in places. Elsewhere however, the localised
alteration of the uppermost flows of Unit 5 may be tenuously interpreted as being a
product of sub-aerial weathering and exposure, possibly indicating a depositional
hiatus. Nevertheless, it is just as likely that the permeation of waters from the
overlying sediments were responsible for this feature and that the USH overlies the
lavas with full conformity. Erosion appears to have been minimal during this period,
as is suggested by the fact that all lava flows in direct contact with the sediments
retain their amygdaloidal tops.
Chapter - 2 - Stratigraphy - 45
Scale
o 2 4 6 8 10
Centimetres
Figure 2.21 Granular sulphide mineralisation in the USH showing conformity to
sedimentary features, possibly as a result of detrital emplacement (sample ER03-1 0).
Figure 2.22 'Framboidal' sulphide mineralisation within the argillaceous
component of the USH. It is possible that this style of mineralisation occurred in-situ
(sample NVTl-l).
Chapter - 2 - Stratigraphy - 46
The USH is overlain unconformably by the sediments of the Bothaville Formation
(Figure 1.2), the plane of which is clearly identifiable by the presence of the coarse
basal Bothaville conglomerate. The USH has sustained varying degrees of erosion
prior to the deposition of the Bothaville Formation. In certain cases where the USH is
omitted from the sequence, the Bothaville Formation is brought into direct contact
with Unit 5.
2.6.1.8 Intrusive Rocks
Distribution. disposition and relationships to other units.
Coarse-grained equigranular mafic sheeted intrusions were encountered in boreholes
ER02 and DKP1 (Figure 2.30). In the case of section DKP1, the intrusion is
approximately 40m in thickness, displaying clear evidence of chilling near its margins, .
as well as the induration of adjacent country rocks. The intrusive body seen in the
aforementioned section occurs along the contact between Unit 5 and the USH, which .l>
probably represents a weakness along which intrusion could take place. In the
majority of instances, however, the principal lines of weakness giving host to intrusive
bodies include structural features such as fault planes (Winter, 1995) and to a lesser
extent jointing.
As is the case in the majority of the Rietgat Formation lavas, the intrusive material
displays a high degree of alteration.
Chapter - 2 - Stratigraphy - 47
2.7 Structural Geology.
Introductory note and previous work.
A dearth of publications pertaining to the structural geology of the Rietgat Formation..
exists at the time of writing. The only material remotely concerned with this topic
includes Meintjes (1988, 1994) and Meintjes et al. (1989), which addresses the
evolution of Ventersdorp-age structural sedimentary basins in the Welkom area.
Stanistreet and McCarthy (1986) and Charlesworth et al. (1986) discussed the
movements of the Rietfontein fault system of the Central Rand Group and its effects
on Platberg sedimentation. Myers et al. (1990) described the dynamic relationship
which existed between Platberg-age structures, sedimentation and volcanism northeast
of Klerksdorp.
Broader studies of late Archaean to early Proterozoic tectonism on the Kaapvaal
eraton include a three-stage model by Clendenin et al. (1988a), which suggests that
the Platberg Group and the Bothaville and Allanridge Formations were emplaced in a
subsiding graben. Much work aimed at the clarification of regional tectonism during
the deposition of the Witwatersrand Supergroup and Klipriviersberg Group has been
undertaken. Such studies include Winter (1986, 1987, 1991), Roering (1986),
McCarthy et al. (1986) and Barton et al. (1986).
Implicit Sfructure ofthe Rietgat Formation in the study area.
Figures 2.23a and 2.23b illustrate the structural geology of the study area and were
extrapolated by Anglovaal geologists during gold reef exploration. These sections are
therefore primarily concerned with the representation of the Upper Witwatersrand
Chapter - 2 - Stratigraphy - 48
sediments and the VCR3. It is possible, however, to infer the structure of the overlying
units with reference to the sections in Figures 2.23a and 2.23b. For instance, it may be
seen that the general structural trend is dominated by near-vertical faults, in
association with very occasional high-angle reverse faults and thrusts (Figure ?.23b).
.>
Moreover, it may be concluded from this fault array that extension was the foremost
tectonic movement during the development of the region.
The faults shown in Figures 2.23a and 2.23b are primarily N-S trending and have
given rise to the formation of a series of grabens and half-grabens. To be of relevance
.to the Rietgat Formation, the foregoing discussion does rely on certain fundamental
presumptions. It is necessary to assume that the Rietgat Formation was subjected to
the same epeirogenic moverrients as the Upper Witwatersrand sediments and the VCR
and that tectonism did not predate the Rietgat. Where age relationships are concerned,
it may be ascertained from Figures 2.23a and 2.23b that particular faults do indeed
displace the Ventersdorp Supergroup, but do not transect the younger Karoo System.
Due to the fact that one of the mam objectives of this study was to establish a
geochemical stratigraphy for the region, the examination was restricted to
untectonised borehole core. Hence only very minor faulting, recognisable by
3 The VCR (Ventersdorp Contact Reef) may be defined as the basal deposit of the Ventersdorp
Supergroup. resting unconformably on the sediments of the underlying Witwatersrand Supergroup
(Coetzee, 1960). Where the VCR is absent, the lavas of the Westonaria Formation (Figure 1.2) mark the
base of the Ventersdorp Supergroup. The VCR is itself a component of the Venterspost Conglomerate
Formation, which comprises a residual sedimentary accumulation (SACS, 1980).
Chapter - 2 - Stratigraphy - 49
®
KARCO·SEElIMENTS & LAVAS
1000- VENTERSDORP LAVAS
-I-J)-
..Q. )'-..
Q) 2000-
..E........
..a.
c.... 3000 - v
Q) v
0 vv
v I
4000 v-~ ~/
I
/
I
I
/
Figure 2.23(a) Section (A)-(B) illustrating the sub-surface structure of the study
area (see Figure 1.3 for location).
: KAROO SEDIMENTS & LAVAS
I VENTERSDORP LAVAS
1000- I , \
I ~ \
"ii)' ! ~v v v v\~ \
Q)
'- 2000- II ~vQ) I v
E· I I v \
'
.--'s::::. 3000- / -~~-ll-.: \,
,\~
,n'\\~ vvv~.!--\_:!-~--I
a.
Q) / v ,,I~l0 fr9~·~ \\N\ 'lI \
4000- / / ~~~ \
!I
I
d;/
.
'1
" 0.1 2 3 4 ~\,
k •"'§it I k:di$'i!\'Qi I l'~
Figure 2.23(b) Section (C)-(D) illustrating the sub-surface structure of the study
area. (see Figure 1.3 for location).
Chapter - 2 - Stratigraphy - 50
"'" '\ o~,
~ ..
" . : g .. 50000
:!'
'"0
'L:
CJ)
C
..o...
.C_U
o MAl
0... TBHI
X
ill
CU 55000
oo NWTI
TNT2
1:5 Po~ib. ~." .. rd __]'
ill extension of" ',.,,,, ~,\ "
IPI
'0._' "DeBronFaulf\~"" ,§0.. . . ·0...... "':,:: OKPIill r SLPIC._J) TNTI~:,,",'::':,AAT2CUf- :"::;~" 5LP2.s " " ' -f:f> ,:~}', . \ SG3en 60000 IST3c , 1 0I<P20,>I\, .:,/c:'" ~
'.6_ SG4
o J, g",o,~"g"
MAL2 MALI
oo
CU .: MALa MALIO
ill
CU MAL7o
(f) " :0> MAL.,'2,
MAL9 DKLI
MAL3
65000 DKL5
DKL2
55 OKL6 LRP3
~~oo~' <or§' S3 RSI
52
56
~
//#'.''/ , POEl POE2(\, '.,,"
ERD2 ER03
-::' I ~'/,:,'", ' 8 AREl
13 12
./ . /.'~.2' 00::\:.',':': :" . II
~------------~-------------+-70000 -+------------~------------~
40000 36500 33000 40000 36500 33000
Figure 2.24 Structure contour diagram (unprojected) for the lower surface of the
Rietgat Formation (this study),
Chapter - 2 - Stratigraphy - 5 I
I c:5c:, 3 D
l( x
>( x
< x
EBSasemenl
x x x
x x x x Xy /" o 25 50 km
x x x x.../.-_'l(" x x
>< x ...x......x x
. Figure 2.25 Structure of the Witwatersrand Basin (after R. Myers et al., 1990)
associated bleaching, chloritisation and occasional rnylonitisation along its plane,
were noted. It was not possible to determine the sense of movement of these faults in
the absence of marker horizons. The presence of faults may. instead be deduced by
more implicit means. Since faulting is largely responsible for the creation of structural
basins into which the lavas and sediments are emplaced, it is possible to infer the
amount of fault movement based on the completeness of a succession. For example,
sections MAL4, ER04 and POEl (Figures2.33, 2.34 and 2.36, respectively) are
relatively incomplete, therefore probably representing either a shallow or marginal
basin environment, or indeed erosion. The nature and disposition of' these
palaeobasins is most readily elucidated by the construction of palaeotopographic
diagrams. Figure 2.24 was plotted using all available borehole data for the study area
Chapter - 2 - Stratigraphy - 52
and represents the lowermost surface of the Rietgat Formation. the existence ofa NW-
SE basinal trend has been interpreted as being a northward extension of the De Bron
Fault (R. Myers et al., 1990; Figure 2.25)
A seismic study of the Allanridge-Bothaville area was undertaken by Anglovaal in
1997 the data from which were not available for inclusion in this study.
2.8 Summary of Strafigraphy and Discussion.
The foregoing paragraphs have demonstrated the fact that the Rietgat Formation may
be sub-divided into distinct units. In summary, the development and stratigraphic
relationships of the Rietgat Formation are as follows:
e The LSH rests with moderate conformity on the Makwassie Formation and is
thought to represent a combination of detrital deposition on a palaeo land surface
and the accumulation scree in the vicinity of fault scarps. It is probable that the
sediments were deposited in topographic depressions during a period of volcanic
quiescence. Alternatively, deposition may have been more widespread, the
sediments having been removed by a subsequent erosive cycle. It is also possible
that the LSH represents a deposit which accumulated on topographic highs which
stood proud of the extruding lavas.
G. Although visually and geochemically discrete, Unit 2 only occurs in conjunction
with Unit 1, of which it is considered a sub-facies. The presence of pillow lavas in
Unit 2 indicates that it was, at least in part, extruded under sub-aqueous conditions.
Chapter - 2 - Stratigraphy - 53
An overlying sedimentary facies, intercalations of which may also be seen between
the pillow structures suggests that sedimentation and volcanism were
contemporaneous.
e Unit 3 succeeds the aforementioned Unit 1-2 package with conformity. The
presence of very well developed examples of the unit in the majority of sections in
the study area is attributed to the rapid extrusion of very large quantities of lava.
Should faulting have been active during this period, it would have had relatively
little effect on the distribution of Unit 3, due to the fact that the rate of extrusion
exceeded fault movement. The absence, furthermore, of sedimentary intercalations
in Unit 3 may also attest to highly expedient extrusion, which could have been of
sufficient magnitude as to eclipse sedimentary processes. Secondly, the volumes of
lava extruded during this period were sufficiently great as to blanket the entire area
irrespective of any palaeohighs.
e Units 4 and 5 are widespread in the study area and form a combined lava package
in which the interdigitation of the two facies is common, the reasons for which will
be explained in terms of petrogenesis later in this study. A widespread feature of
Units 4 and 5 are their sedimentary intercalations, which comprise quartzwackes
and shales. These sediments are in greatest abundance higher in the sequence,
possibly due to waning of volcanism and the increased role of sedimentation during
this period. Further evidence to support this theory may be gleaned from the fact
that the lava flows higher in the sequence become successively thinner, pointing to
a gradual cessation of volcanism.
Chapter - 2 - Stratigraphy - 54
o The Upper Sedimentary Horizon (USH) represents the complete dominance of
sedimentary processes following the culmination of volcanism. This concurs with
the gradual waning of volcanism that took place throughout the emplacement of
Units 4 and 5.
o The lithologies of the USH suggest a period distinguished by very calm,
widespread, low energy, deep-water conditions. The fact that diamictites and
breccias are absent from this horizon, suggests that there was either no coarse
elastic input to the basin or that the USH in this region merely represents a distal
facies.
I) The upper surface of the USH is unconformably truncated by the basal
conglomerate of the overlying Bothaville Formation.
fI Fauiting is one of the most conceivable mechanisms governing the distribution of ~,
the Rietgat Formation. It is highly probable that faulting played a role in the
development of the structural sub-basins into which the lavas and sediments were
emplaced. Lava distribution may also have been governed by the disposition of
extrusive centres. The widespread distribution of the USH and Units 4 and 5 and
presence of elasties therein has, with caution, been attributed to the abatement of
fault movement later in Rietgat times. In explanation, fault movement can govern
the development of structural basins, which in turn may restrict the distribution of
sediments and volcanielastics. Furthermore, faulting could be responsible for the
II
development of scarps, from which coarse elastic wedges may be derived.
Chapter - 2 - Stratigraphy - 55
On a concluding note, it should be stated that the preceding discussion and concepts
contained therein conform to lithostratigraphic" precedents. Given the fact that
faulting appears to have been ongoing throughout the emplacement of much of the
Rietgat Formation, extreme relative displacement of litho logical units may-occur. It is
therefore :very difficult to classify units on. chronostratigraphic'' grounds.: Such
movements may lead to the omission of certain units on a localised basis. Technically,
such breaks may be termed unconformities, though since in this case they are
contemporaneous with extrusion/sedimentation elsewhere, have not been considered
. thus. In short, a sequence strati graphic approach has been adopted by this study; for
further details, the reader is referred to Van Wagoner et al. (1988).
,I Lithostrarigraphy, 'The elements of stratigraphy which deal with the lithology of strata and their
organisation into units based on lithological character' Bates and Jackson (1980).
5 Chronostratigraphy, , The branch of stratigraphy that deals with the age of strata and their time
relations' Bates and Jackson (1980).
Chapter - 2 - Stratigraphy - 56
Geo.!ogy Ni/Zr
D.v»v Highly aHered lava, aphyrlc to porphyritlc In
Uvvv places.1335
Ash layer.
cf~
UNIT4
1360 AHered grey lava, generally non-amygdaloldal.
~~ Porphyrltic In places and containing occasional
/t~ lapilli.
1385 '~0
c:::x::x:::t)
0000 Amygdaloidal lava containing chlorite amygdales.
a 00 0
1410 .;'
UNIT 5
.,:::' .:: ~ Evidence of bleaching In places .
Densely amygdaloidal grey-green lava.
1435
Epidote facies.
Amygdaloidallava with quartz and chlorite fillings.
1460
Epidote facies.
....... 1485
eVI Mered lava; variably amygdaloldal (l-8mm 0).
.Qsi 1510
"'VVVV
s: 'Vvv."."
ë. vvvvv
al "''''."VY
0 vvvvv~535 .. '! '" 'If V ~VVVV"
"VVVII
Sporadically amygdaloidal lava, green to grey in
vvvvv
.,vvvv colour: Individual now units are difficuH to
1560 UNIT 3distinguish. Vuggy quartz in places.
1585
Sub-aphanitic layered unit. Possibly of volcanic
1610 origin.
1635 Sporadically amygdaloidal lava, displaying a well
developed plagioclase porphyry towards Its base.
1660
Very fine-grained amygdaloidallava.
1685 Epidote facies.
Sporadically amygdaloidallava.
1710
Figure 2.26 Lithological and geochemical stratigraphy for borehole NVTl,
Chapter - 2 - Stratigraphy - 57
Geology Ni/Zr
Sporadically amygdaloidallava, conlinued.
1735 UNIT 3
Very dense lava containlng occasional plagioclase
;
laths. Blebby chlorite throughout.
1760 -----------------
Mered horizon with mottled appearance.
1785
en Sedimentary unn: shaly Intercatatlons near basee grading upwards Into quartzwackes. Occasional
'(jj 1810 metallic sulphides may be seen.
S UNIT 2
s:
ë.
Q) 1835
0
Highly altered pillow lavas in a shale/massive
sulphide matrix.
1860
------------------ ----
1885
Aphanltic to porphyritic lavas containing breccia
horizons. Possibly a pseudotachy1ne, clast size UNIT 1
1910 up to and including 6cm 0.
-----
Sulphide-rich shales and quartZwackes. SEDIMENT
Figure 2.26 (cont'd) . Lithological and geochemical stratigraphy for borehole
NVTl.
Chapter - 2 - Stratigraphy - 58
Geology Ni/Zr P20s/Zr
8 ~ § §
ti 0 ti ti
Ouartzwacke containing shale partings. Cross
830 bedding and slump structures in places. Small SEDIMENT
quantities of buckshot pyrite may also be seen.
855
Highly anered amygdaloidallava.
PorphyrHic lava.
UNIT 5
880 Mnnotonous amygdaloidallava.
0000
£ .~ :. ", • :' :'
905 Grey lava flows, generally equigranular, with
occasional chlorHe-filled amygdales near now UNIT4
tops only.
930 -j,.;r-"6+-~2f!~~~~_£Olii"fu"ill!'ë_}i~-::_--=--=--====--=- UNIT 5
Vuggy equigranular lava. UNIT4
955
Monotonous, grey amygdaloidal lava, aHered in_
980 places. Occasional quartz-filled vugs. Indistinct
li)
Q) now contacts.
'-
ga3 1005
s:
ë.. Very thin amygdaloidallilva nows.
Q)
0 1030
UNIT 3
1055
Sporadically amygdaloidal lavas displaying
variolitic alteration in places. Occasional quartz
vugs « 5cm 0).
1080
1105
Sporadically amygdaloidal inequigranular lava.
AphanHc in places.
1130
1155
PorphyrHic lava, pale green In colour. Contains
subhedral feldspar laths, which become coarser UNIT1
lower down In now unH.
1180
1205
Figure 2.27 Lithological and geochemical stratigraphy for borehole MA 1.
Chapter - 2 - Stratigraphy - 59
Geology
8
cj
Ouartzwacke, coarsening downwards from fine
655 sand to grit. SEDIMENT
680 Veined, altered amygdaloldallava.
Intensely altered lava with occasional amygdales:
variolitic in places.
705
Ouartzwacke. UNIT 5
730 r-~....,- A~daloida.!_!ava. _
Numerous lava flows, generally aphanilic, thin
and non-amygdaloidal.
755 UNIT4
Thin lava flows, densely amygdaloidal in places.
780 -h"",,..,,..,;I-- ---------------Vuggy porphyrHic lava.
Amygdaloldal porphyry. UNIT 5
805 Aphyric to porphyrHic lava.
éï)
Cl>
'-
.(isj 830
s:
ë..
Cl> Sporadically amygdaloidal lava flows, typically 3-
0 855 7m in thickness, containing vuggy quartz in
places. Amygdales commonly contain chloritic
fillings.
880
Banded mylonite. UNIT 3
905
Sporadically amygdaloldal lava, aphanitic to fine-
grained.
930
Identifiable now units with amygdaloldal tops and
porphyrHic centres. Lewermost flows commonly
contain quartz veins and vugs.
980
POfPhyritic lava, coarsest near now centre.
1005
UNIT 1
Coarse grey quartzlfeldspar porphyry, possibly a
correlate of the Garfield Member (Winter, 1976).
1030
Figure 2.28 Lithological and geochernicai stratigraphy for borehole KFN2,
Chapter - 2 - Stratigraphy - 60
Geology
8
d
Shale containing metallic sulphides. SEDIMENT
725
Numerous lava nows. mostly amygdaloidal and
equigranular; also occasional aphanitic horizons,
Bleached upper surface. - perhaps due to sub-
750 aerial exposure.
UNITS
Amygdaloidal porphyry.
800
Aphanitic lava displaying variolitic alteration ..
825 Lava flows, amygdaloidal throughout.
850
li)
e Sporadically amygdaloidal lavas, the Individual
Q) 875 units of which are extremely difficult to discern.g
sa:.
(1)
0 900 UNIT 3
Sporadically amygdaloidal lava flows, as above. 3
Amygdale fillings are typically oi chlorite and or
chalcedony.
950
975
Sporadically amygdaloidal grey lava flows, as
above.
1000
Ouartzwackeldiamictite.
Amygdaloidal porphyry.
1025
Porphyritic lava containing chlorite blebs UNIT 1
1050
Moderately coarse porphyritic lava.
Figure 2.29 Lithological and geochemical stratigraphy for borehole TNT2.
Chapter - 2 - Stratigraphy - 61
Ceoloqy
B
ei
Silly shale. containing occasional carbonates and
830 buckshot metallic sulphides (- 1
SEDIMENT
%).
855
Equlgranular mafic Intrusive material. Coarse
throughout. with the exception of the chilled
880 margins.
905 High density aphanltic green lava. Very thick now
units. the Iowennost of which tends towards a
porphyrilic texture.
930
"iii'
Q.l
'-
4i 955 Coarse mafic intrusive.g
s:
ë..
Q.l 980
0
1005 Abundantly amygdaloldal lava flows. The now top
of the uppermost unit displays brecciation.
Amygdale fillings are typically of chalcedony and
quartz. 0.1
UNIT2
lOSS Amygdaloidallava.
1080
Coarse quartz/feldspar porphyry flow units.
Possibly a correlate of the Garfield Member UNIT 1
(Winter. 1976).
1105
Figure 2.30 Lithological and geochemical stratigraphy for borehole DKPl.
Chapter - 2 - Stratigraphy - 62
Geology Ni/Zr ./
o8
675 Ouartzwacke with very fine clay Intercalations
containing buckshot metallic sulphides. Dark grey SEDIMENT
coloration .
900
925
Numerous amygdaloidal lava flows, highly altered
near their contact with the overlying sediments.
950 Chalcedony vugs and veining are common, 'with
variol~ic alteration manifesting itself from place to UNIT 5
place. The centre most nows are finely plagioclase
porphyritic.
975
1000 Altered amygdaloidal lava containing occasional
'ii)
Cl) quartz vugs.
aL:-;
g Matrix-supported breccia with siliceous matrix,1025 possibly of volcanic origin.
s:
li
Cl)
0 1050
1075
UNIT 3
Numerous. indistinct, sporadically amygdaloidal
lava nows. Scoriaceous texture in places. Variably
1100 grey to green in colour. Amygdale fillings are
either of chalcedony or chlorite.
1125
1150
1175 Basal chert horizon.
Ouartzlfeldspar porphyry showing a moderate UNIT2
degree of variolitic alteration.
4-=':"--*+----------------,---
1200 Coarse quartzlfeldspar porphyry: chlorite blebs. UNIT 1
·1
Figure 2.31 Lithological and geochemical stratigraphy for borehole MA2.
Chapter - 2 - Stratigraphy - 63
Geology Ni/Zr
8
ti
697
Numerous flows of altered, densely amygdaloidal
lava. UNITS
720 ~~=r.]'~c ~!9!~ularïaVa ïïows.-=--=--=--=- -=--== UNIT4
745 Lava flows. generally amygdaloidal - densely so in
places. Some flow-centres are finely plagioclase- UNIT S
porphyritic.
770
Densely amygdaloldal aphanitic lava.
795
820
Numerous quartz/feldspar porphyry lava flows
845 .with amygdaloldal flow tops In places. UNIT 1
870
895 Coarse quartz/feldspar porphyry.
...iJ~.
Figure 2.32 Lithological and geochemical stratigraphy for borehole MAL 1.
Chapter - 2 - Stratigraphy - 64
Geology
8
ti
Fine grey shale containing sandy partings. SEDIMENT
755
UNIT4
'-----
Greyish-green non-amygdaloidal porphyry.
780
Cii"
Q...). Coarse, amygdaloldallava.
ai
805 UNITS_§. Fine porphyry with amygdaloidal flow-top.
s:
li
Q) Thin amygdaloidallava " aphyric In places.
0 830
Numerous, sporadically amygdaloldal lava nows
with scoriaceous appearance.
855
UNIT 3
Densely amygdaloldallava. Bleached near top.
880
Figure 2.33 Lithological and geochemical stratigraphy for borehole MAL4.
.. ;
Geology Ni/Zr
8
ti
A protuse number or aHered amygdaloldal lava
nows. Average thickness < 1m.
Grey amygdaloidal lava containing quartz vugs;
660 very fine-grained to aphanitlc,
Ceii"
gai 685 UNIT SSparsely amygdaloidal grey aphyric lava. Finely
s: porphyrnic in place with chlorite blebs. Mottled
.0. appearance near base.
Cl)
0 710
Sporadically amygdaloidallava.
735 UNIT 3
Figure 2.34 Lithological and geochemical stratigraphy for borehole ER04.
Chapter - 2 - Stratigraphy - 65
Geology
720
Shales and sms with occasional sandy partings. SEDIMENT
745 Grey lava containing large (- 9mm 0) chalcedony
amygdales.
(i)'
,C_l) 770
Q)
g
Massive plagioclase-porphyr~ic lava. Coarsens
s:
li 795
UNITS
towards centre, with chlorite blebs In places.
Cl)
0
820
Numerous, thin amygdaloldallava flows. Vuggy In
845 --j;.'T:3<2-d-e...~....:..._--------------DlamlctHe, containing angular lava clasts In a
carbonate matrix. SEDIMENT
Figure 2.35 Lithological and geochemical stratigraphy for borehole S6.
Geology Ni/Zr P20s/Zr
i!! § §
d ti cj
760 Anered lava flows, variolitic In places. Amygdalesare generally restricted lo the now tops. Well
developed fiows may be vuggy and porphyritic in
(i)'
~ places. Possibly contains a pyroclastlcJIuffaceous
Q) 785 component.
g UNIT S
s:
li
Cl) 810o
835 Dark green siliceous diamictite.
SedimenVash layer.
Figure 2.36 Lithological and geochemical stratigraphy for borehole POE 1.
Chapter - 2 - Stratigraphy - 66
Geology Ni/Zr P20s/Zr
B ~ § ~
ei ti 0
Medium to dark grey lava; quartz veiniets and
715 stringers common. Blebs or metallic sulphides. SEDIMENT
+-::-=====1------------------
Abundant thin lava !lows.
740 Shale.
Anered amygdaloidallava, varloëtic in places.
........ 765 Thin, aphannic lava nows.
(/)
~ Shale, containing blebs or metallic sulphides.
Q) Epldote racies. UNIT4
S 790 Shale.
oe -t-:::-=--+-~IlbM.~.li.~ -
ë..
Q)
0 Massive lava flows, typically amygdaloidal near815 now tops. More developed units have a porphyritic
flow centre.
Some very fine-grained aphanitic horizons - may UNITS
840 be or turraceous origin.
865
UNIT3
890 - --- SEDIMENT
Figure 2.37 Lithological and geochemical stratigraphy for borehole S4.
Geology
699
720 Lava containing chloritic amygdales.
'iii'
Q...).
Q) Grey equigranular lava; shows variolnic aneration.
S 745
oe
ë.. Dense clark green amygdaloidal lava, amygdales
.Q)
no becoming more sparse near to flow base.0
Densely amygdaloidallava.
795 SliiëëOUSdiamlCiitë:-------- -- ----
Figure 2.38 Lithological and geochemical stratigraphy for borehole DKL6
Chapter - 2 - Stratigraphy - 67
CHAPTER 3: MINERALOGY AND PETROGRAPHY.
3.1 Introduction.
A summary of the mineralogy and petrography of the Rietgat Formation is presented
in the following chapter. Many of the observations contained herein are of relevance
to the geochemistry and petrogenesis of the rocks in question. These issues will,
however, be addressed in subsequent chapters. The aims and objectives of this chapter
are as follows:
o To identify the mineral phases present in the rock and whether these are the
product of primary igneous or secondary alteration processes.
o To delimit the metamorphic facies.
o To determine whether any mineralogical or textural variation exists between the
units comprising the Rietgat Formation.
The following commentary is presented in terms of the geochemical stratigraphic units
as described in the previous chapter. A summary of the principal textural and
mineralogical characteristics of the Rietgat Formation is presented in Table 3.1.
Where necessary, further subdivision of the units has been undertaken.
3.2 Brief note on previous work
T. B. Bowen (1984) discussed the petrography of the Rietgat and Goedgenoeg
Formations in the broader context of the Witwatersrand triad: this study placed
Chapter 3 - Mineralogy & Petrography - 68
emphasis on the significance of petrography to geochemistry. Winter (1965) also
commented briefly on the petrography of the Rietgat Formation, though this too was
presented in the context of the entire Ventersdorp Supergroup. Similar studies specific
to other Ventersdorp Supergroup Formations are instructive since they give an insight
into the methods by which altered lavas may be examined and classified. Such
material includes Winter (1995) who studied the Alberton Formation, Linton (1992),
who investigated the Klipriviersberg Group and Meintjies (1998) who examined the
Makwassie Formation.
3.3 Techniques Employed
Mineralogical and petrographic examination of the Rietgat Formation was conducted
primarily by optical means. Non-reflective opaque phases were identified at the
University of the Free State using a CAMECA electron-microprobe. All samples were
furthermore subjected to powder XRD6 analysis to determine the mineral assemblage
present. Given that the XRD technique employed was non-quantitative, it was not
possible to derive modal mineralogical compositions for the samples
6 X-ray diffraction (XRD) is a non-destructive analytical technique for the identification of mineral
phases present in powdered and solid samples. The Siemens 05000 diffractometer and associated
OIFFRAC-AT (V 3.0) software at the University of the Free State automatically measure and record the
. sprecrraproduced by the individual mineralogical constituents in the powder sample. Identification is
achieved by comparing the XRD spectra obtained from the unknown sample with a database containing
reference patterns for a large number of standard phases.
Chapter 3 - Mineralogy & Petrography - 69
Table 3.1 Summary mineralogy and petrography for the Rietgat Formation.
UNIT MINERALOGY TEXTURES PLATE(S)
Almost entirely quartz with very Relatively mature; fining-upwards
occasional plagioclasc grains und lithic sequences. 3.13,3.14,
Upper Sediment fragments. Shaly material contains 3.15
sulphide mineralisation in places.
Dominant plagioclasc; interstitial Coarsely intersertal to hyalopilitic.
calcite and chlorite, with minor
5 clinozoisitc and epidote. Occasional 3.12
opaqucs.
Twinned plagioclase, blebby chloritc, Intersertal to hyalopilitic. Stellate
clinozoisite and occasional epidore. clustering of plagioclase.
4 3.11
Plagioclase (mostly saussuritised to Hyalopilitic to pilotaxitic. Amygdalcs
clinozoisite), quartz and chlorite with contain quartz filling; (concentrically-
facies I very occasional opaque sphene and zoned according to crystal size). 3.7
ilmenite.
Acicular plagioclase, intersitlal quartz TIle mass of the rock is pilotaxitic.
and opaque material (sphene and . Amygdales arc concentrically-zoned
3 facies II ilmenitc). Uncharacteristically devoid and contain quartz, calcite and 3.9,3.10
of chloritc. c1inozoisite.
Containing plagioclase, chloritc, Crystalloblastic and aphanitic. TIle
actinolite, epidote and disseminated amygdale filling; are either of
facies III opaques. Quartz manifests itself as homogeneous quartz and/or calcite, 3.8
silicification. bordered by clinozoisite rim.
Porphyritic plagioclase, altered to Weakly porphyritic to aphyric,
clinozoisite. Calcified and silicified. displaying relict hyalopilitic texture;
2 glomeroporphyritic in places. 3.5,3.6
Plagioclase, chloritc, quartz and ITIle overall texture is porphyritic, with I
opaques (sphene and ilmenite). intersertal to crystalloblastic' , I
1 Calcified and silicified. groundmass. 3.3,3.4
Mineral grains principally of quartz Clasts are angular and in generally
and occasionally plagioclase. Lithic immature with respect to their texture
Lower Sediment clasts of lava. Secondary calcite. and mineralogy. 3.1,3.2
Cl iuopyroxene, which has undergone Coarsely-crystalline and equigranular ..
moderate chloritisation. Remnant Sub-ophitic in places.
Intrusive Material biotitc, plagioclase and actinolite. nla
Mineral grains predominantly of quartz Corrosion textures/reaction rims at
and feldspar. Calcification and clast margins. Matrix contains
Pseudotachylitc silicification common, Occasional blebs crystallization products and imbrication 3.16,3.17
of clinozoisite and epidote. of constituent clasts.
Furthermore, given the detection limits of XRD (-3% by weight, G. 1. Beukes, pers.
comm., 1999), some minor phases may escape identification. It is necessary therefore
Chapter 3 - Mineralogy & Petrography - 70
to use both optical and X-ray techniques in conjunction with one another in order to
determine the mineralogical composition.
3.4 Unit by Unit petrographic appraisal of the Rietgat Formation.
3.4.1 Lower Sedimentary Horizon (LSH).
The sediments of the LSH are texturally and mineralogically immature as may be seen
from Figures 3.1 and 3.2. Clasts are generally angular, ranging in size from <lmm, up
to 10mm. Many of the larger clasts are of lithic origin, showing remnant intersertal
and hyalopilitic'' igneous textures. Mineral grains - principally of quartz but
occasionally. of plagioclase may also been seen, some of which display undulose
extinction. This is a metamorphic feature and has been interpreted as being a
characteristic of the source from which the sediment was derived. In the case of
sample DKL8-14, secondary calcite pervades the entire sample as vein material and
interstitial fillings. Unlike the USH, the sediments of the LSH are matrix-supported.
The matrix is almost entirely of very fine-grained quartz, which although difficult to
examine appears to be highly crystalline, possibly as a result of secondary fluid
processes. Secondary clinozoisite forms thin rims around some of the lava fragments.
7 An intersertal texture comprises an unorientated meshwork of feldspar laths in which the gaps are
tilled by glass or very fine crystals, the feldspar crystals forming a major part of the rock (decrease in
feldspar content results in a variety of ophitic texture (Whitten & Brooks, 1973).
8 A hyalopilitic texture is a variety ofpilotaxitic texture in which the felt of the crystals or crystallites is
embedded in a glassy base (Whitten & Brooks, 1973).
Chapter 3 - Mineralogy & Petrography - 71
3.4.2 Unit 1 (Lower Garfield Member).
Unit 1 is distinctively plagioclase porphyritic and in the case of sample DKPI-IO, the
groundmass is coarse, intersertal and in places crystalloblastie (Figures 3.3 and 3.4).
Extensive and pervasive silicification are present as well as calcification (the latter
being restricted to interstices only). Xenornorphic'" opaques (possibly ilmenite or
sphene) occupy many of the interstices and clinozoisite replaces plagioclase feldspars.
Elsewhere, the plagioclase is sufficiently fresh as to permit the identification of
euhedral phenocrysts. In the case ofMALl-7, the host groundmass comprises smaller
intersertal plagioclase crystals, the interstices of which are filled by opaques and
highly pleochroic chlorite minerals. Patches of finely saccaroidal secondary quartz
occur on a sporadic basis, containing variable quantities of calcite. In contrast to
MAL 1-7 and DI(P 1-10, tv1AL1-8 has not undergone such a degree of silicificatieri or
calcification. Instead, chloritisation appears to have been more prevalent, particularly
at an interstitial level. The chlorite phases possibly owe their origin to alteration of
.primary biotite, remnants of which may be seen along primary cleavage planes.
9 Crystalloblastic is a term used to describe the texture produced by the simultaneous recrystallisation of
several minerals as a result of metamorphic processes. A characteristic feature of the texture thus
produced is that any of the minerals involved may be found as inclusions in any of the other minerals
(Whitten & Brooks, 1973).
10 The term 'xenomorphic' may be applied to a mineral which displays no crystal shape (Whitten &
Brooks, 1973).
Chapter 3 - Mineralogy & Petrography - 72
Figure 3.1 Lower Sedimentary Horizon, clastic component primarily of quartz. The
range in clast size and angularity is suggestive of textural immaturity. The matrix is
now heavily chloritised and the occasional euhedral opaques (A) are probably sphene
(PPL).
Figure 3.2 Lower Sedimentary Horizon, fining upwards from (A) to (B): the finer
grained material typically has a darker colour-index than the coarser material. The
rock is now heavily chloritised and also contains metal sulphides, both of which were
probably derived by secondary processes. (Incident light).
Chapter 3 - Mineralogy & Petrography - 73
Figure 3.3 Unit 1 - non-pleochroic euhedral plagioclase laths dominate the sample
and are set in a chloritised silicified groundmass. Plagioclase is commonly
saussuritised to clinozoisite (present in this sample as a highly pleochroic brown
mineral), most notably along twin planes (PPL).
Figure 3.4 Unit 1 - highly altered example of the Lower Garfield Member
exhibiting widespread chloritisation (greenish-yellow pleochroic mineral (A» and
saussuritisation. The parallel gashes are thought to be shock-related and are possibly
derived from the nearby Vredefort impact structure (Colliston, pers. comm., 1998)
(PPL).
Chapter 3 - Mineralogy & Petrography - 74
Figure 3.5 A relatively fresh example of Unit 2. Secondary chlorite occurs as an
interstitial groundmass phase (A) and as more prominent blebs throughout the sample
(B). The plagioclase content of this unit is far less coarse than that seen in Unit 1
(PPL).
Figure 3.6 Unit 2 - groundmass displays heavy alteration. Subhedral phenocrysts
(A), originally of plagioclase feldspar are now fully altered to clinozoisite. Remnant
plagioclase is also visible as a groundmass phase. Opaques are disseminated at
random throughout the groundmass but are not present in the phenocrysts (PPL).
Chapter 3 - Mineralogy & Petrography - 75
3.4.3 Unit 2 (Upper Garfleid Member).
As Figures 3.5 and :'3.6illustrate, the rocks of Unit 2 are weakly porphyritic (NVT1-
47) to aphyric'v-Many examples (such as NVTI-46b) display a relict hyalopilitic
texture comprising a felted quart:zJchloritic groundmass hosting intersertal plagioclase
laths, clinozoisite and calcite. Isolated relict plagioclase phenocrysts are observed,
which in most cases are now completely or almost completely altered to clinozoisite,
visible as a distinct 'berlin blue' colour in XPL.
Local variations in texture and mineralogy within Unit 2 may occur, most probably in
response to different .levels. of alteration. For example, NVTI-48 represents a finer
grained crystalloblastic sample that has undergone severe alteration. Unit 2 may also
be glomeroporphyritic'f in places: where this is the case, the altered feldspar laths are
more visible than those in the surrounding rock. Some feldspars have undergone such
high degrees of saussuritisation that primary features such as twinning have been
completely obliterated. Conversely, DKP 1-9 is very fresh in comparison to the above,
as is evident from its clear crystal morphology. The primary texture is sub-ophitic':',
with secondary chlorite manifesting itself as both an interstitial groundmass phase, as
well as more prominent blebs throughout the sample.
II The term 'aphyric' may be applied to a phenocryst-poor volcanic rock (Whitelaw, pers. com., 1998).
12 A glomeroporphyritic rock is one with a porphyritic texture in which groups of crystals (either of the
same mineral or of different minerals) are scattered through a finer-grained groundmass (Whitten &
Brooks, 1973).
13 An ophitic/sub-ophitic texture is one in which augite encloses plagioclase (Whitten & Brooks, 1973).
Chapter 3 - Mineralogy & Petrography - 76
3.4.4 Unit 3 (Central Rietgat Member).
Following a detailed optical examination of specimens taken from Unit 3 in a number
of boreholes, it is concluded that three distinct facies exist. This subdivision is based
on primary textural characteristics (summarised in Table 3.1) and is as follows:
Facies I.
The rocks comprising this facies are typically fine-grained, consisting of fine acicular
plagioclase in a groundmass ofxenomorphic quartz and chlorite (see Figure 3.7). The
overall texture of the facies is hyalopilitic to pilotaxitic'" with occasional calcite
present as interstitial fillings only. Where clinozoisites are present, varying degrees of
saussuritisation of the parent feldspar are identified, showing distinctive green
pleochroism and high relief in PPL. An important characteristic of this facies is its
zoned .amygdales, 2-3mm0, which contain quartz fillings concentrically zoned
according to grain size. Anhedral opaques, determined by electron-microprobe
analysis to be sphene and ilmenite, are disseminated throughout the entire facies, with
the exception of its amygdaloidal component. It should be noted that due to the poor
quality of the· samples and consequent 'burning-out' of mineral phases during
electron-microprobe analysis, this technique was not as widely employed as would
have been desired.
14 A pilotaxitic texture comprises a felted mass of acicular or lath-like crystals, sometimes showing flow
structures (Whitten & Brooks. 1973).
Chapter 3 - Mineralogy & Petrography - 77
Figure 3.7 Unit 3, Facies I - Amygdales contain quartz fillings concentrically zoned
according to crystal size. This zonation is visible in high relief due to the presence of
pleochroic chlorite at grain boundaries. The groundmass comprises microcrystalline
quartz, chlorite and plagioclase, together with a high proportion of opaques (PPL).
Figure 3.8 Unit 3, Facies III - Dense, fine-grained crystalloblastic groundmass
comprising quartz, chlorite, plagioclase and opaque minerals (sphene or ilmenite).
Amygdale fillings consist of concentrically zoned rims of quartz (A), chlorite (B) and
calcite (C) (PPL).
Chapter 3 - Mineralogy & Petrography - 78
Figure 3.9 Unit 3, Facies II - Groundmass comprises a high proportion of opaque
material (sphene and/or ilmenite), together with pilotaxitic plagioclase. The
amygdales are concentrically zoned and contain fillings of calcite (A) and clinozoisite
(B). The calcite is readily visible due to the high relief ofits 120° cleavage (PPL).
Figure 3.10 Unit 3, Facies II - Groundmass comprises a high proportion of
opaques, in association with acicular plagioclase. Amygdales contain distinctive
'berlin-blue' clinozoisite core (A) and calcite rim (B) showing low-order birefringence
colours (XPL).
Chapter 3 - Mineralogy & Petrography - 79
Figure 3.11 Unit 4 - Moderately equigranular intersertal plagioclase feldspar
showing saussuritisation in places (A). Patchy silicification (B) tends to occur in
association with chloritisation. Opaques are disseminated throughout the entire rock,
though are commonly interstitial (PPL).
Figure 3.12 Unit 5 - Coarsely intersertal euhedral plagioclase laths (A) in a fine
matrix of green pleochroic chlorite and quartz. Opaques appear to occur on a very
sporadic basis only and never appear to transect the plagioclase laths (PPL).
Chapter 3 - Mineralogy & Petrography - 80
Facies II.
This facies is exemplified by TNT2-11 (Figures 3.9 and 3.10) and is more or less fully
pilotaxitic, comprising acicular plagioclase and fine interstitial quartz and opaque
minerals. As is the case with facies I, the opaques are of sphene and/or ilmenite.
TNT2-11, unlike most of the Rietgat Formation is more or less devoid of chlorite. The
amygdale fillings of facies II comprise concentrically zoned rims of clinozoisite,
quartz and calcite of low birefringence.
Facies III
Facies III (typified by NVTI-23; Figure 3.8) comprises a completely crystalloblastic
mass of aphanitic'f plagioclase, clinochlore, epidote and occasional actinolite. Patchy
silicification may be seen and as is the case with facies I and II, disseminated opaques
are common. Amygdales are either of homogeneous calcite (displaying 102° cleavage
throughout) or coarsely saccaroidal quartz, the latter becoming coarser towards the
core of the amygdalc. Both arnygdale types generally posses a very thin rim of berlin-
blue clinozoisite and in the case of the quartz amygdales a rim of calcite.
3.4.5 Unit 4 (Upper Rietgat Member - Non-Amygdaloidal),
Twinned plagioclase crystals are prominent in Unit 4, where they typically display an
intersertal/hyalopilitic texture (KFN2-8; Figure 3.11). Zoned and hollow plagioclase
crystals were identified, which according to Lofgren (1972) are a product of cooling
rates. Occasional glomeroporphyritic clusters of more finely grained plagioclase may
Chapter 3 - Mineralogy & Petrography - 81
also be seen. Unit 4 contains occasional epidote «1 %) and more commonly blebby
green pleochroic chlorite. Clinozoisite is recognised in Unit 4 where it manifests itself
as a saussuritisation product of plagioclase. Two crystallographic orientations may be
seen in the clinozoisite, one giving rise to a characteristic Berlin-blue colour in XPL
and the other to a brown colour, following remnant twinning planes.
3.4.6 Unit 5 (Upper Rietgat Member - Amygdaloidal),
The rocks of Unit 5 are petrographically similar to those of Unit 4, save for the
presence of amygdales in the former. Unit 5 is typically dominated by coarse
intersertal, idornorphic'" twinned plagioclase with hyalopilitic tendencies in places
(see MA2-3; Figure 3.12). The interstices of Unit 5 rriay be filled by either a very fine
greenish mineral (high relief in PPL) or by calcite. Calcite may in some cases also be
present as fine stringers where it commonly associates with minor blue clinozoisite.
Small quantities (-5%) of highly pleochroic brown material - completely opaque in
certain cases are tentatively described as sphene. Unit 5 contains a submorphous
groundmass of fine quartz and very occasional epidote «1 %), identifiable by its high
birefringence in XPL.
3.4.7 Upper Sedimentary Horizon (USlHl).
In all cases, the clast size of the USH ranges between 0.2 and 1.5 mm 0. Furthermore,
the clasts themselves are almost entirely of quartz composition (together with very
15 The term 'aphanitic' is a textural term used to describe igneous rocks having such fine grains that
individual constituents are not visible to the naked eye, but are visible under suitable magnification
Chapter 3 - Mineralogy & Petrography - 82
occasional plagioclase grains and lava fragments) indicating a reasonably high degree
of mineralogical maturity (see Figures 3.13 and 3.14). In terms of their texture, the
clasts are sub-angular to sub-rounded, indicating a moderate degree of textural
maturity and therefore a high degree of sediment working. Fining-upward cycles may
be seen, albeit on a small scale (the thickness of these laminae typically being in the
order of lem).
Although in a broad sense, the USH is petrographically homogeneous, some minor
localised variations are observed. For example, while secondary calcification is
commonplace in ZTD 1-1 (particularly in its coarsest layers), DKL8-7 is completely
devoid of such mineralisation and is of virtually pure quartz composition. ZTD 1-1 is
c1ast-supported and since it contains virtually no matrix may be considered unimodal
in terms of its grain-size distribution. Although in the case of DKL8-7, many of the
constituent clasts are in contact with one another, a considerable number are separated
by small amounts of highly silicified matrix. This sample therefore displays a strongly
bimodal grain-size distribution. Hence it is debatable as to whether DKL8-7 is clast-
or matrix-supported. These inconsistencies have been attributed in part to localised
facies variations as well as differing levels of secondary alteration.
Occasional epidote grams, readily identifiable by their high order birefringence
colours, were dispersed throughout the USH regardless offacies variety. It is proposed
that the epidote is an in-situ alteration product and that it was not derived in its present
state from pre-existing rocks.
(Whitten & Brooks, 1973).
16 An idiomorphic rock is one which displays a fully developed crystal form (Whitten & Brooks, 1973).
Chapter 3 - Mineralogy & Petrography - 83
A
I. .... •
Figure 3.13 Upper Sedimentary Horizon - Comprises sub-rounded quartz grains
(A), lithic fragments (B) and calcite (C) - possibly secondary and displaying cleavage
planes in moderate relief. This sediment is texturally mature as is indicated by its
unimodal size distribution (PPL).
A
l
Figure 3.14 Upper Sedimentary Horizon - Comprises sub-rounded quartz grains (A)
and lithic fragments (B) which are possibly of lava. Calcite (C) displays low-order
birefringence colours and probably arises from the calcification of pre-existing
material (XPL).
Chapter 3 - Mineralogy & Petrography - 84
Figure 3.15 illustrates the euhedral metallic sulphides (specifically pyrite, chalcopyrite
and pyrrhotite) which occur in conjunction with the shale constituent of the USH. It is
proposed that this association results from the fact that metallic sulphides form readily
under the euxinic genetic conditions typical for many shale facies.
A briefnote on the possible correlation oOhe USH with the sediments at T'Kuip.
As will be discussed in Section 4.5, an attempt was made to correlate the rocks of the
Platberg and Pniel Groups in the Allanridge-Bothaville area with the exposed Sodium
Group rocks at T'Kuip. It is possible that the sedimentary unit outeropping in
association with the lavas of the Rietgat Formation at T'Kuip may represent a USH
correlative. A dearth of surface exposure in the T'Kuip area rendered it impossible to
discern the exact strati graphic position of the outcrop. Correlation is complicated
further by the fact that the sediments at T'Kuip are petrographically distinct from both
the USH and the Bothaville Formation as seen in the Free State. It is proposed that
this is the product of a facies variation.
3.4.8 Intrusive Rocks.
The sheeted mafic intrusives encountered in the study area are typically coarsely
crystalline and equigranular, containing a high proportion of clinopyroxene, which
have undergone moderate chloritisation (ER02-1). Relatively large plagioclase laths
(4mm) are barely discernable due to the high degree of saussuritisation which they
have undergone. An ophitic relationship between the plagioclase and clinopyroxene
may be seen, though it is not widespread. Occasional amphiboles, principally
Chapter 3 - Mineralogy & Petrography - 85
Plate 3.15 Upper Sedimentary Horizon - Reflected light microscopy reveals the
presence of euhedral pyrite grains (A). It is proposed that this mineralisation took
place in-situ and took the form of nucleation around microscopic detrital sulphide
grains (Reflected light).
actinolite, and hornblende were identified. No olivine remnants were recognised and
saccaroidal quartz appears to be restricted to pervasive secondary occurrences
3.4.9 Pseudotachylites
Reference was made in Chapter 2 to isolated pseudotachylite occurrences in borehole
NVTl. Although petrographically similar to ignimbrites and rheoignimbrites,
pseudotachylites have been distinguished from tuffaceous material on the basis of the
criteria (Colliston and Reimold, 1994) presented on page 88.
Chapter 3 - Mineralogy & Petrography - 86
Figure 3.16 Pseudotachylite - Banding of the matrix is readily discernable (A): this
is possibly a flow-structure. The remainder of the sample comprises a range of mineral
grains (B), which are predominantly of quartz and display a marked range in grain-
size and angularity (PPL).
Figure 3.17 Pseudotachylite - Lithic fragment (A) of feldspar porphyry shows
slight corrosion at its outer rim. The matrix contains mineral grains, particularly of
quartz (B) in addition to abundant opaque material. Chloritisation of the sample is "
moderate and imbrication of mineral grains - particularly quartz - is notable (PPL).
Chapter 3 - Mineralogy & Petrography - 87
• Identification of crystallisation products in the matrix.
G Presence of vesicles.
e Corrosion textures/reaction rims at clast margins.
(I) Partial or complete assimilation of clasts into the matrix.
o Sintering textures within clasts.
Figures 3.16 and 3.17 depict the pseudotachylite as it is seen in the study area. Its
mineral grains are predominantly of quartz with occasional plagioclase feldspar; lithic
fragments are usually of porphyritic lava. The clastic component of the
pseudotachylite is generally upwards of 1mm in diameter, sub- to well rounded and
commonly annealed. In accordance with the above criteria for pseudotachylite
recognition, the clasts frequently show reaction rims and display signs of corrosion at
their margins - possibly a precursor to their assimilation of the clasts into the matrix.
The matrix itself shows an advanced degree of crystallisation, which further
substantiates the theory that this material is pseudotachylitic. Notable structures in the
matrix include very fine banding, very high proportions of opaque material and
imbrication of constituent clasts. Minor amounts of epidote and clinozoisite occur on
a sporadic basis, particularly in the matrix and are assumed to be of secondary
provenance.
Chapter 3 - Mineralogy & Petrography - 88
3.5 Mineralogical Trends as identified by XRD.
3.5.1 Introductory Note.
XRD analysis of 223 Rietgat Formation samples was undertaken, the purpose of
which was to determine whether any mineralogical variation exists within or between
units. A cross-section of samples from all lava units, sediments and tuffs were selected
for this exercise. Regrettably however, not all of the T'Kuip samples were available at
the time of analysis, hence the limited nature of the data from this location in
Appendix 2. XRD was also used to assess the degree of lateral mineralogical
homogeneity of the units in the study area.
It is necessary at this stage to explain the nature of the data referred to in this section.
In the case of the present study, the XRD data is non-quantitative. As such it is only
possible to affirm the presence of a mineral phase and not its specific abundance.
All of the XRD interpretations generated by this study are presented in Appendix 2,
where they are arranged according to unit of origin. The following paragraphs aim to
identify and interpret trends in this data and are organised in terms of mineralogy.
Ferroan clinochlore.
This mineral is present in all of the samples, with the exception of MA 1-11, which
instead appears to be intensely epidotised. In virtually all cases, a very strong primary
XRD peak. is seen with .respect to ferroan clinochlore, suggesting a relatively high
abundance.
Chapter 3 - Mineralogy & Petrography - 89
Quartz.
All of the analysed samples were found to contain a quartz component. The intensity
of the primary quartz peak was seen to vary markedly in proportion to the relative
abundance of this mineral.
Albite/calcian albite.
Where present, plagioclase feldspar manifests itself as either albite or calcian albite.
This mineral was recognised throughout Units 1, 2 and 3 in the large majority of
boreholes. Plagioclase feldspars are present in the lowermost portions of Units 4 and 5
but are absent in the upper horizons of these units. The tuffs are completely devoid of
all plagioclase feldspars.
Muscovite.
The main noteworthy muscovite occurrences in the Rietgat Formation may be found
in the upper horizons of Units 4 and 5. Muscovite is also common in Unit 2, scarce in
Unit 1 and almost completely absent in Unit 3. A strongly inverse relationship
between muscovite and albite abundance appears to exist which may be explained in
terms of metamorphism. Theoretical isograds (Figure 3.18) delineating this
association were constructed using PTX, a computer program for DOS (Perkins el al.,
1986). Since PTX was unable to proffer a satisfactory relationship between albite and
muscovite, anorthite was instead taken to represent the plagioclase content of the
lavas. It is possible that anorthite may have undergone albitisation as a result of fluid
processes subsequent to metamorphism.
Chapter 3 - Mineralogy & Petrography - 90
4000 -
~
Vl
I.-
eo 3000 -e--o-
2000 -
o ~--------------~I--------------~I--------------~I------------~
350 400 450 500 550
Temperature (oC)
Figure 3.18 P-T stability fields for a system containing muscovite and anorthite.
10000 I l
I
8000 -
~
Vl
Ie.o-
eo 6000 --Q-)-
'-
:::J
Vl
Vl
Q) 4000 -
l.-
o,
2000 -
o ~------------~I--------------~I------------~~I----------~
400 450 500 550 600
Temperature (oC)
Figure 3.19 P-T stability fields for a system containing actinolite and calcite.
Chapter 3 - Mineralogy & Petrography - 9 t
Epidole.
Although widely identifiable by petrographic means at all strati graphic levels, epidote
was only ver} rarely observed in XRD patterns. A consequence of the relatively low
abundance of epidote is that it often falls below the detection limits of XRD (~ 3%, G.
J. Beukes, pers. comm., 1999). Accordingly, no clear mineralogical trends were
elucidated by XRD with regard to epidote and stratigraphy. Epidote was only
recognised in XRD samples obtained from the intensely altered zones as described in
Chapter 2.
Biotite.
This mineral was only encountered in its fresh state in certain intrusive samples. It is
possible however that biotite also existed in the lavas and that this underwent
alteration to chlorite. Biotite distribution may also attributed to primary minerlogical
variations between the intrusive material and the lavas.
Calcite
The distribution of calcite appears to be extremely sporadic, varying from hole to hole
and from unit to unit. For example, calcite was observed throughout boreholes S4,
ER04, MALI and DKPI in their entirety. Conversely, boreholes KFN2 and TNT2 are
completely devoid of this mineral. Other boreholes (S6, DKL6, MAL4, MAl, MA2
and NVT 1) show varying degrees of calcification, ranging from the advanced
calcification of entire units, through moderate levels of calcification to a complete
calcite absence.
Chapter 3 - Mineralogy & Petrography - 92
Actinolite/{erro-actinolile.
A moderately inverse relationship between ferro-actinolite and calcite abundancies is
noted. Hence, actinolite distribution in the Rietgat Formation in the study area is
roughly antipathetic to calcite distribution. Theoretical isograds depicting this
relationship are again extrapolated using PTX and are shown in Figure 3.19.
3.6 Normative Mineralogical Classification of the Rietgat Formation.
3.6.1 Introduction.
The norm calculation is a means by which the mineralogy of a rock may be derived
from the results of a geochemical analysis. The most widely used classification
scheme is the CIPW -norm, the specifics of which may be found in Rollinson (1993).
The normative mineralogical composition of a rock may differ substantially from the
observed modal composition; this is due to the following simplifying assumptions.
() The calculations assume that the parent magma was anhydrous, therefore minerals
such as hornblende and biotite are absent from the classification.
() No account is taken of solid solution between Ti and Al in ferromagnesian
minerals.
I/) The Fe:Mg ratio in all ferromagnesian minerals is assumed to be the same.
• The CIPW-norm. is derived from geochemical data only and disregards the effects
of crystal size.
Chapter 3 - Mineralogy & Petrography - 93
Currie (1991) proposed that for altered mafic volcanic rocks, the CIPW -norm yields
results that closely resemble the original modal composition. It therefore follows that
CIPW-normative analyses are of particular use in estimating the primary mineral
phases that have subsequently been replaced by metamorphic minerals.
CIPW norms were calculated for all 412 geochemical analyses undertaken in this
study and are presented in Appendix 3. Mean CIPW-norm values for each unit of the
Rietgat Formation (excluding tuffaceous and sedimentary units) are given in Table
3.2, an interpretation of which is presented in the following paragraphs.
Quartz.
Normative quartz may be derived for all of the units of the Rietgat Formation (Table
3.2). Unit 3 contains a significantly lower quartz component (11.31 %) relative to all of
the other units (-20%). Since normative quartz is calculated from excess Si02 (i.e.
that already not held in honds with other oxides), it follows that Unit 3 has; on :,.
average, a lower Si02 content (Table 3.2).
Ilmenite, sphene & rulile.
The normative ilmenite, sphene and rutile values are a function of Ti02 content. If
FeO < TiO], then an excess of Ti02 is allocated to sphene in proportion to the CaO
content of the sample (only after CaO has been allocated to anorthite, see below). If
there is still an excess of Ti02, it is apportioned to rutile. With reference to the data in
Table 3.2, it may be seen that Units 1 and 5 contain both normative sphene and rutile,
suggesting a relatively high Ti02 excess. Ccnversely, Unit 3 and the intrusive material
contain sphene only, which is indicative of a lower Ti02 excess. In the cases of Units
Chapter 3 - Mineralogy & Petrography - 94
Table 3.2 Mean CIPW-norm. compositions for the units of the Rietgat Formation.
LJNIT
/ 2 3 4 5 Intrusives
Quartz 19.99 22.11 11.31 20.34 20.59 18.51
Corundum - 0.14 - 3.47 - -
Zircon 0.07 0.08 0.05 0.07 0.06 0.04
Orthoclase 9.67 14.97 3.93 8.04 7.80 8.06
Albite 23.39 23.07 27.47 21.48 19.34 17.63
Anorthite 22.52 20.58 25.55 21.00 27.34 22.86
Diopside - - 0.79 - - 3.32
Hypersthene 10.10 7.45 13.30 10.89 10.80 11.12
Chromite 0.08 0.06 0.06 0.04 0.04 0.03
Haematite 9.84 8.98 11.72 11.33 10.37 14.53
Ilmenite 0.24 0.23 0.29 0.30 0.27 0.48
Sphene 2.97 - 3.74 - 0.81 3.15
Apatite 1.43 1.36 2.08 1.81 1.76 0.53
Rutile 0.03 1.29 - 1.48 1.06 -
n= 25 7 76 35 82 7
I I
TOTAL /00.33 /00.32 /00.29 /00.25 /00.24 /00.26
2 and 4, the fact that normative rutile is present and sphene absent may be explained
in terms of CaO stoichiometry. It is likely that the original CaO concentrations in
these units were sufficiently low as to have been allocated in full to anorthite (see
below). As a result, no excess CaO was available to buffer Ti02 in sphene nucleation,
hence excess Ti02 contributes instead to the formation of rutile.
Chapter 3 - Mineralogy & Petrography - 95
Feldspar minerals
With regard to the feldspar minerals, orthoclase, albite and anorthite crystallise as a
result of a buffering relationship between Ah03 and K20, Na20 and CaO~
respectively. Any geochemical variations (with respect to K20, Na20 and CaO) w~,bin
and between the units of the Rietgat Formation are reflected in their feldspar.
mineralogies. Cross-referencing of the K20, Na20 and CaO in Table 3.3 with the
normative feldspar data in Table 3.2 serves to confirm this relationship.
Corundum.
Any Ah03 111 excess of CaO following anorthite crystallisation goes to form
normative corundum. Since Units 2 and 4 are corundum-normative (Table 3.2), one
would expect their Ah03 content to be relatively high in accordance with the above
rule. Although this principle may be applied in the case of Unit 4 (Table 3.3), Unit 2 -
to the contrary - contains a relatively low concentration of Ah03. The allocation of
Ah03 to corundum in the case of Unit 2 is probabiy a function of its low Na20, CaO
and K20 contents, resulting in a lower degree of buffering of Ah03 by the feldspars
(possibly due to alteration).
Pyroxenes.
With reference to the pyroxene minerals, an excess of CaO over AI203 is allocated
with an equal amount of MgO + FeO to normative diopside. Any remaining MgO +
FeO goes to form hypersthene. In the case of the present study, normative diopside
was only encountered in Unit 3, suggesting that overall, this is the only unit in which a
CaO excess comes about. In all of the units, an MgO + FeO excess occurs regardless
Chapter 3 - Mineralogy & Petrography - 96
of whether diopside is crystallised. As a result, normative hypersthene is present in all.
of the units.
Table 3.3 Mean oxide compositions for the units of the Rietgat Formation.
/"
UN][T
,
1 2 3 4 5 Intrusives
Si02 56.56 57.60 50.91 52.48 54.70 53.38
Ti02 1.30 1.34 1.54 1.55 1.45 1.53
AI20J 13.90 14.05 14.43 15.81 14.45 13.18
Fe20J 9.28 8.48 10.74 10.60 9.80 14.09
MnO 0.11 0.11 0.13 0.13 0.12 0.21
MgO 3.80 .2.83 4.99 4.07 4.02 5.23
CaO 5.77 4.51 7.11 5.08 6.16 6.46
Na20 2.62 2.57 3.04 2.09 2.30 2.21
KzO 1.59 2.40 0.72 1.51 1.20 1.17
P20s 0.57 0.54 0.78 0.72 0.69 0.26
1I2O- 0.07 0.06 0.07 0.07 0.07 0.14
. LOl I 3.57 4.16 4.06 5.36 5.24 2.34 I
n= 25 7 76 35 82 7
TOTAL 99.15 98.66 98.54 99.48 100.20 100.20
Apatite.
Finally, normative apatite (present in all of the units) crystallises in response to a P20S
presence, haematite to an Fe203 excess and chromite and zircon to Cr and Zr excesses
respectively.
Chapter 3 - Mineralogy & Petrography - 97
3.7 Veins and Vuggy Quartz Occurrences.
Quartz veining may be observed throughout the Ventersdorp Supergroup in the study
area. This material appears to show little or no conformity to any formation or lithological
unit within the Supergroup and as such is somewhat sporadic in its distribution. The veins
themselves range in size from hairline-size fillings.: through veiniets (~ 1cm) to larger
bodies of up to 25cm cross-section. Perhaps the most common mode of vein occurrence
seen in the study area are the extensive stringer networks which pervade many metres of
borehole core. These networks may possibly result from the movement of fluids along
structurally-derived fissure planes. During their passage, these fluids gave rise to both
wall rock alteration (up to lem from the fissure) as well as the precipitation of small
quantities of vein quartz and/or chalcedony.
In the larger of the aforementioned vein systems, more diverse mineral assemblages may
be seen, on both macro- and microscopic scales. These typically comprise coarse-grained
quartz, in addition .to variable quantities of calcite, chlorite and epidote. Texturally, the
larger vein systems exhibit a saccaroidal texture, which is at its coarsest towards the
centre of the body. The chlorite and epidote may have either been entrained from adjacent
rocks by the circulating hydrothermal fluids, or instead have been derived during the
greenschist facies metamorphism of the entire lava pile. Thermometric analyses offluid
inclusions (Section 3.7.1) have been used in an.attempt to elucidate the nature of the fluid
event responsible for the emplacement of the quartz veins.
Vuggy quartz is also extremely common throughout the entire Ventersdorp Supergroup.
Vugs range in size from 10mm up to several centimetres in cross-section, usually
Chapter 3 - Mineralogy & Petrography - 98
associating with amygdales. The vug fillings are typically of quartz/chalcedony together
with varying amounts of calcite and/or chlorite. In general, the larger the vug, the coarser
its filling and the more diverse its mineralogical constituent. Zonation is quite common;
this giving rise to agates. Vugs are at their most abundant in Units 3 and 5 of the Rietgat
Formation, typically occurring nearer to the base of the I~va flows rather than the top ...'
Vugs do not appear to associate with the sedimentary or porphyritic facies of the Rietgat
Formation and are extremely scarce in non-amygdaloidal units.
3.7.], Thermometric Analysis - Introductien and Principles.
Thermometric analysis is concerned with the investigation of fluid inclusions .trapped in
their solid host. Further details concerning both the techniques and the principals of fluid
inclusion analysis may be found in Shepherd et al. (1985), Chapters 4:.6.
Analyses were undertaken at the University of the Free State using separate Chaixmeca
heating and 'cooling stages, in conjunction with a Leitz biological microscope equipped
. with a UV filter. Heating was effected by an electrical resistance heater and cooling by the
circulation of gaseous nitrogen in the presence of silica gel in order to prevent
condensation. Rock wafers, polished on both sides, were prepared from vug material:
such samples provide the best source of inclusions, since hydrothermal veins tend toyield
poorer quality material (Shepherd el. al., 1985). Sample selection was made on the basis
of available material.
Chapter 3 - Mineralogy & Petrography - 99
Freezing studies.
Freezing studies were used to measure the salinity of the inclusions. Under aqueous
conditions, the freezing point of water varies in proportion to the amount of salt in
solution. Since a variety of chemical systems may-manifest themselves in fluid inclusions
(these being chlorides, sulphates and carbonates of Fe.jvlg, Ca, Na and K in combination
with water) it is first necessary to ascertain the precise nature of the brine. This may be
deduced from the eutectic temperature of the system, this being the point at which first
melting occurs in a fully frozen inclusion. In the case of the present study, the eutectic
temperature was determined to be approximately -21°C. With reference to published data
(Shepherd-er al., 1985), this corresponds closely to the eutectic temperature for the system
H20 +NaCl.
Heating studies.
The ultimate aim of heating studies is to measure the homogenisation temperature, this
being the temperature at which the' inclusion becomes a one-phase system. By comparison
. with freezing studies, the phase changes observed at high temperatures are relatively
uncomplicated. Homogenisation of the liquid and vapour H20 + NaCI phases in the
. current study led to the solution of the vapour phase into the liquid state. The precise point
at which the vapour bubble goes into exsolution is known as the homogenisation
temperature: this was found to be between 56°C and 206°C for the observed populations.
3.7.2 Interpretation and synthesis of results.
The most effective means of representation of thermometric data are histograms and.
bivariate plots, since these provide an immediate appreci;:tti.on of any groupings or
Chapter 3 - Mineralogy & Petrography - 100
populations which may be present. When plotted, the data showed moderate bimodal
distribution indicating the presence of more than one inclusion population, possibly
resulting from the presence of C02 in certain inclusions.
The object of this excercise has been to constrain the relationships - if any - between the
veins and vugs and the greenschist metamorphic event. Although the temperature at
.. which the veins and vugs were emplaced has already been elucidated, this alone is of little
.. value in the Clarification of a possible relationship to a metamorphic facies. It is also
necessary to calculate the pressure at which trapping. took place. Using the method of
Shepherd et. al. (1985), the inclusions in wafers ER02-5 and DKL5-19 were found to
have been trapped at temperatures between 84.5° and 206.6°C at a pressure of between
0.59 and 18.69 bars Pressure conditions were found to be similar for all of the inclusion
populations studied. With reference to Winkler (1974), these pressure conditions are
clearly far outside the bounds of greenschist facies metamorphism. It has been concluded
for the purposes of this study that the veins and vugs are the product of a later
hydrothermal event.
3.7.3 Discussion and Interpretation of Mineralogy.
The following section arms to summanse and interpret the mineralogical trends
identified in this chapter.
. One of the most noteworthy mineralogical features of the Rietgat Formation is its
paragenesis. As has already been noted, the assemblage typically comprises chlorite,
. quartz, albite ± actinolite ± epidote, which according to Deer et al. (1993) is
Chapter 3 - Mineralogy & Petrography - 101
commonly representative of greenschist facies metamorphism. The P-T conditions for
such a paragenesis are in the order of 400°C at a few kilobars (Deer et al., 1993).
With regard to the minerals comprising the greenschist facies assemblage, it IS
important to note the following:
• Chlorite is a common hydrothermal alteration product of the of biotite, pyroxenes
and amphiboles in igneous rocks (Deer el al., 1993). Furthermore, the composition
of the chlorite is often related to the composition of the original rock. In the case
of the present study, the chlorite is principally Fe-rich (ferroan-clinochlore),
reflecting its role in the replacement of an Fe-rich ferromagnesian phase. Chlorite
is also a common amygdale filling in the lavas and is a product of intense
hydrothermal alteration.
9 Aithough occurring principally as a product of greenschist facies metamorphism
(as described above), epidore and clinezeisite may also occur as a hydrothermal
alteration product. This mode of epidotisation is generally confined to joints,
fissures and amygdales.
.• Albite may be a product of both greenschist facies metamorphism and primary.
magmatic processes (plagioclase feldspars being one of the most important
constituents of basic and intermediate lavas): It is therefore contentious as to
whether the albite component of the lavas was derived by primary or secondary
processes. In the case of the present study however, it is probable that.both of these
processes have operated.
Chapter 3 - Mineralogy & Petrography - 102
In section 3.6, the presence of certain accessory phases were noted. One such mineral
is ilmenite, some of which is a product of primary crystallisation, but much of which
is derived from Ti-magnetite during cooling. Sphene is also a widespread accessory
mineral in igneous rocks, where it is the dominant Ti-bearing mineral (Deer et. al.,
1993).
The metallic sulphide (pyrite, pyrrhotite and chalcopyrite) component of the Rietgat
Formation is, as previously discussed, confined to the sedimentary portions of the
Formation. It is possible that these sulphides formed by either sedimentary or
diagenetic processes under reducing conditions.
The interpretations of the preceding paragraphs are based on the mineralogy of the
Rietgat Formation as deduced by XRD analysis and petrography. A somewhat
different mineral paragenesis was however elucidated by CIPW -normative
calculation. Although some of the normative mineral constituents (such as the
plagioclase feldspars, quartz, ilmenite and sphene) were identifiable by petrographic
means, most were confined to the CIPW -norm only. This discrepancy may be
accounted for at least in part by the simplifying assumptions of the norm calculation
itself. It is also proposed that the results of the Cll'Wenorm reflect the primary
mineralogical composition of the lavas prior to greenschist facies metamorphism. The
presence of feldspars, quartz and pyroxenes in the norm are indeed characteristic
components of basic to intermediate lavas. Minerals such as rutile, corundum, zircon,
chromite and haematite are all common accessories in igneous rocks and serve no
diagnostic purpose in this study. The fact that chlorite, epidote and clinozoisite are
absent from the norm goes to substantiate the fact that they are indeed secondary
Chapter 3 - Mineralogy & Petrography - 103
products. Vugs and quartz veining were found to have been trapped at temperatures
between 84.5° and 206.6°C at a pressure of between 0.59 and 18.69 bars. Such
temperatures and pressures conform to neither an extrusive igneous or a greenseliist
facies metamorphic event and are hence may be considered to be of subsequent origin.
Chapter 3 - Mineralogy & Petrography - 104
CHAPTER 4: GEOCHEMICAL STRATIGRAPHY.
4.1 Introduction.
The problem with litho logical stratigraphic classifications is that they are prone to
misinterpretation and are not always conducive to long-range correlation. In contrast,
geochemical strati graphic methods are easy to apply and in the case of the
Ventersdorp Supergroup are laterally consistent over a wide area (Linton, 1992).
The main aim of the following chapter is therefore to elucidate the geochemical .
differences between the lavas of the Rietgat Formation. Parameters by which
unknown samples may be classified into their respective units are also proposed. It
should be emphasised that this chapter deals only with the more practical applications
of geochemistry: petrogenetics and magmatic characterisation are discussed in
Chapter 5.
The formulation of geochemical discrimination techniques arises out of the following
needs. Firstly, it is desirable to estimate the depth to reef during exploration drilling,
allowing decisions to be made regarding the continuation of boreholes. The
fundamental assumption in this case is that the thickness of the Rietgat and underlying
formations are known with certainty in the area. Secondly, geochemical stratigraphy
may also be applied in the resolution of structural problems. Such issues include the
loss of strati graphic units due to normal faulting and the repetition of units due to
reverse faulting and/or thrusting. The extrapolation of these structures to the
Chapter - 4 - Geochemical Stratigraphy - 105
underlying reef may contribute towards the structural interpretation of the region and
its ore bodies.
4.2 Previous Work.
Perhaps the most comprehensive approach to the geochemical subdivision of lava
units (in this case the Alberton Formation of the Klipriviersberg Group) is that of
Winter (1995). In his study, Winter (ibid.) first examined chemical variations with
stratigraphic height by means of univariate (element or oxide versus depth) plots.
Since this exercise failed to highlight any geochemical variation between horizons,
Winter instead sought to detect clustering or linear variation in the data by plotting
paired variables on a series of scatter plots. Winter (ibid) concluded that this method
provided satisfactory discrimination between horizons. However, he also considered it
desirable to involve all of the .elemental variables simultaneously in the same
classification scheme and employed multivariate statistical techniques to this end .... -
Having assessed the shortcomings of both element-element bivariate plots and ternary
diagrams, Linton (1995) concluded that the only discrimination technique of value in
the categorisation of lava suites is discriminant function analysis. This is due to the
fact that the increased number of variables utilised by this technique provide a tighter
constraint on the positioning of the fields.
Chapter - 4 - Geochemical Stratigraphy - 106
4.3 The Geochemical Stratigraphy of the Rietgat Formation.
The following paragraphs aim to identify any geochemical characteristics and trends
present in the lavas of the Rietgat Formation. A variety of graphical and statistical
discrimination techniques have been used to this effect.
4.3.1 Univarlate Analysis: Geochemical Variation with Stratigraphic Height,
Experimental geochemical profiles (element versus depth) were constructed for all .
boreholes with respect to all major oxides and trace elements. The aim of this exercise
was to determine whether any vertical geochemical variation exists within the profile
and if so whether such .features can be correlated between holes. Given the fact that
this exercise generated nearly 500 individual plots, only those identifying the clearest
.trends were selected for inclusion in this study, an explanation of which follows,
.In the majority of cases, the morphology of the down-hole elemental profiles is
somewhat irregular, rendering their interpretation a complex process. An approach.
similar to that of Myers et al. (1990) involving immobile trace elements (Zr, Ti/Zr and
Cr) and their inter-relationships was also tested on the data set, though due to the
disparate nature of the plots, no clear trends were evident. Consequently, reviews of
only two principle ratios have been included in the present study, these being Ni/Zr
and P20s/Zr versus depth (Figures 2.26-2.38). The ratio of Ni to Zr was chosen since
it is representative of fractionation (a relatively low Ni/Zr ratio is indicative of a
relatively high degree of fractionation - see Chapter 5) and P20S to Zr since these"
elements are fundamental to the sub-division of the Rietgat Formation (Figure 2.3). In
.Chapter - 4 - Geochemical Stratigraphy - .107
contrast to most other trace element and major oxide variables, the ratios of N i to Zr
and of P20s to Zr (Figures 2.26-2.38) were found to display relatively clear vertical
zonation, which may be correlated laterally and which is applicable to all sections.
Units 1 and 2 show relatively low Ni/Zr values, though these are still higher than those
displayed by Units 4 and 5. In most cases, the Unit 1 Ni/Zr value is very slightly
elevated in relation to that of Unit 2. The Ni/Zr ratio of the intrusive material is far in
excess of that of the lavas by which it is hosted. Unit 3 exhibits far higher Ni/Zr ratios
than the rest of the Rietgat Formation, a trend which is most acute towards the centre
of this unit. In comparison to Unit 3, Unit 4 displays a relatively low Ni/Zr ratio, as
.does Unit 5 in the majority of sections. In certain sections Unit 4 does, albeit on a
minor scale, display Ni/Zr elevation relative to Unit 5.
With regard to the P20S/Zr ratios, the observed trends are very similar to those
dispiayed by Ni/Zr. Units 1 and 2 display consistently low values, Unit 3 displays an ..
elevated P20S/Zr ratio, which is consistent throughout the unit. Units 4 and 5 exhibit
relatively low P20S/Zr ratios; it is not possible on a linear plot to differentiate between
the two units on this basis.
A large degree of scatter was observed in many of the profiles that were not included
in this study. This may be attributed to alteration, particularly in the case of the more
mobile variables such as Rb, Ba, Sr, Na20 and CaO. Conversely, it is also possible
that a more limited scatter of data points is indicative of better geochemical
preservation. Dispersal of the data may also be attributed to magmatic processes, such
as contamination, mixing and fractionation.
Chapter - 4 - Geochemical Stratigraphy - 108
In summary, the lavas do - with the exception of a small number of anomalous
samples - exhibit similar geochemical trends between boreholes, indicating that the
lavas are laterally homogenous. Minor vertical geochernical variation do however
exist, these being a function of litho logical variation and/oralteration.
4.3.2 Bivartate Analysis: Scatter Plots.
The previous exercise highlighted only subtle geochemical differences between the
stratigraphic units. It has therefore been deemed necessary to employ an alternative
discrimination technique with a view to establishing a more clear-cut geochemical
constraint on stratigraphy. To this end a number of X-Y element-element scatter plots
have been compiled. Such scatter plots are of use in that they may reveal both
. clustering and lineation, where present, in the data set. The propensity of variables to
increase or decrease in proportion or inverse proportion to one' another may also be
observed from this type of diagram.
Initially this exercise involved the construction of 529 bivariate plots representing
every combination of the 23 variables plotted against one another. Only the plots
displaying the clearest and most representative data trends were however chosen for
inclusion in this study, a summary of which follows.
It was first noted that the only scatter plots to show any clear data trends were those
containing Ti02, P20S, Zr, Cr and V (i.e. relatively immobile elements) as at least one
of the variables. This is illustrated by Figures 4.4 to 4.6, which all exhibit varying
scales of clustering of the data points. Plots including Zs as a variable do however
Chapter - 4 - Geochemical Stratigraphy - 109
appear to reveal the tightest clustering and least amount of overlap of the data. A plot
of Zr versus P20s (Figure 2.3) was indeed used in Chapter 2 as a fundamental
mechanism for the geochemical subdivision of the Rietgat Formation. Plots including
V as a variable (Figures 4.1 - 4.16) also facilitate the recognition of individual units,
though the clustering of the data is less dense. While Units 1 to 3 are clearly defined
on V-plots, a certain amount of overlap between Units 4 and 5 does however occur.
Plots which use P20s as a variable tend towards a more dispersed appearance with
more overlap between all units. Distinct fields may nonetheless be recognised,
particularly in the case of Units 1 to 3 on a plot ofP20s versus Nb (Figure 4.12). Cr as
a variable is also of use in the constraint of geochemical stratigraphic units, though it
generally produces fields of data rather than the tight clusters characteristic of other
diagrams. The level of overlap is however minimal.
As has been demonstrated (Figure 2.3), clustering of the data facilitates the
identification of discrete geochemical units. The existence of such sharp geochemica)
discontinuities between the units may be a function of petrogenetic aspects - a topic
which will be addressed in Chapter 5.
Certain plots (eg. Ti02 versus P20S, Figure 4.7) do give an initial impression that
lineation is present in the data. Although such trends can represent the petrogenetic
development of a unit, closer examination of the data has revealed that no relationship
exists between stratigraphic height and relative position in a geochemicallineation.
T. B. Bowen (1984) and Bowen et al. (1986a, 1986b) also applied element-element
scatter plots to the discrimination of lavas. The aforementioned authors have proposed
Chapter - 4 - Geochemical Stratigraphy - 110
that a plot of Ti/P versus P/Zr is the best means by which to characterise the volcanic
rocks of the Witwatersrand Triad. Although this method provides accurate
discrimination between the lavas of the Ventersdorp Supergroup as a w~lOle, the
elemental variations within the Rietgat Formation are, as Figures 4.1-7 and 4.18
suggest too small to facilitate the demarcation of individual units.
Chapter - 4 - Geochemical Stratigraphy - III
2.1r-----~~~~_~_~~~~--~~__~__~--~~--~--~~__,
Unit 1
Unit 2 °l
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1.1 L-~ __ ~ __ ~~~ __ ~~~~~~~~ __ ~~ ~~~ ~ __ ~~ ~~~
150 210 270 330 390 450 510
lr(ppm)
Figure 4.1 Scatter plot of Zr versus Ti02 (this study).
1.2 r-~--~~:-~~~~:- :-~~~~~~ ~~~~~
lig Unit 1
l> Unit 2
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I: <?; i: Cl o00lCl: 1: '.,. i:
0.4 ~~~~~~---- ~~ __ ~ __ ~~ ~~~~~~ ~
150 210 270 330 390 450 510
lr (ppm)
Figure 4.2 Scatter plot of Zr versus P205 (this study).
Chapter - 4 - Geochemical Stratigraphy - 112
450~~--~-:~--~~:-~~~~;-~~~-, __ ~~ __ :-~~~~
~ el Cl) Unit 1 I .
c :0 Unit 2
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50~~~~~----~~~~~~~~----~~~-- __~~L_~~~~
150 210 270 330 390 450 510
Zr (ppm)
Figure 4.3 Scatter plot of Zr versus Cr (this study).
480 r-~-~~-~-r-~~---~~-~----~-~~-~~---~-~~--~-,
Unit 1
Unit 2
o
400 ~ Unit 3·······································I··~·"······"············15··.·..·····1" · ····.····· 1 0 1. 0 Unit4
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160L-~----~--~---:-------~~~~--~:-~~~------L_-:-~ : __~~
100 160 220 280 340 400
V(ppm)
Figure 4.4 Scatter plot of V versus Zr (this study).
Chapter - 4 - Geochemical Stratigraphy - 113
160 r-~~~~--r-~~~--~:-~~~----:---~~----:-~ __~~--,
120 J 0 !~:o.TJ':~1 i:° Unit 1Unit 2Unit 3Unit 4
; 0 ~ <? 0>%<>
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100 160 220 280 340 400
V (ppm)
Figure 4.5 Scatter plot of V versus Ni (this study).
.A...C.,.V" - y_._ .•-~ '-'~-,.---~~----,-~-~----,--~~-~---.----~......=::::..,
o o o o Unit 1
oj 0 0 O. o 1::. o o o j Ao Unit 20
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100 160 220 280 340 400
V (ppm)
Figure 4.6 Scatter plot of V versus Cr (this study).
Chapter ..4 ..Geochemical Stratigraphy .. 114
1.2r.=========~----~----~--~-----:----------:---~----1
o Unit 1
Unit 2
o Unit3
1.0 . o Unit 4 l ; ; ; ~ ..
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1.1 1.3 1.5 1.ï 1.9 2.1
Ti02 (wt%)
Figure 4.7 Scatter plot of Ti02 versus P20s (this study).
160 r-----~----~------------~----~----~------~~--~----~----~
o Unit 1
~ Unit 2
120 ....................................... 1 0..~~~~.J g l ~.~ : +. o ~~:~!c 0 00: e 00 ooi 0 i 0 Unit 5
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Ti02 (wt%)
Figure 4.8 Scatter plot of'fiOi versus Ni (this study).
Chapter - 4 - Geochemical Stratigraphy - I 15
60 r-------~~~--~----~--------~----~--~~------~~~--~--_,
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Unit 2 CJ
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20~~~--~~~~--~~~~~~~--~~----~~--~~--~-~-~~----~~--~
0.45 0.55 0.65 0.75 0.85 0.95 1.05
P205 (wt%)
Figure 4.9 Scatter plot OfP20S versus Y (this study).
! •. ~.
E
aa..
0.55 0.65 0.75 0.85 0.95 1.05
P205 (INt%)
Figure 4.10 Scatter plot OfP20S versus Sc (this study).
Chapter - 4 - Geochemical Stratigraphy - 116
160r-~~----,_~~~--,_~--~~~~--~_,,_~--~--,_~~~_,
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0.45 0.55 0.65 0.75. 0.85 0.95 1.05
P205 (wt%)
Figure 4.H Scatter plot OfP20S versus Ni (this study).
25 ;-:---~~-'---~~-~:-Tc-.--- -I· 0 - -.- T ·'-'1-+ .
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0.45 0.55 0.65 0.75 0.85 0.95 1.05
P205 (wt%)
Figure 4.12 Scatter plot ofP20S versus Nb (this study).
Chapter - 4 - Geochemical Stratigraphy - 117
450.-~~~~--~--.~-,~--~---:~~--~:-~~~--:-~-----'~
-0 ;.~:0. 0: Unit 1Unit 2
o 0 ClO 0 cj ; 0 0 Unit 3
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0.45 0.55 0.65 0.75 0.85 0.95 1.05
P205 (wt%)
Figure 4.13 Scatter plot ofP20s versus Cr (this study).
2.1
VI 0 cj : ~~:~ ~
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1.1 ~~~~~~~--~~ __ ~~~~~~ __ ~ __ ~ __ ~~_L~ __ ~~~~~~
50 100 150 200 250 300 350 400 450
Cr(ppm)
Figure 4.14 Scatter plot of Cr versus Ti02 (this study).
Chapter - 4 - Geochemical Stratigraphy - 118
150r-~~~~~~~~~~~~~~~~~~-,--~~;-~~~:-~~--,
o
120 ······················I························!························I··············:o=t;;i;;~~OFO~O.OO=~ ;; ~ ~ .
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30 ······················I~:~~ol·········I·mmm-I·_~m·_·11 ~ ~~i;~
o~~~~~~~~~~~~~~~~----~------~------~----~
50 100 150 200 250 300 350 400 450
Cr (ppm)
Figure 4.15 Scatter plot of Cr versus Ni (this study).
E
aa..
.0
Z 12
Unit 1
Unit 2
8 o Unit 3
o Unit4
o Unit 5
100 150 200 250 300 350 400
Cr(ppm)
Figure 4.16 Scatter plot of Cr versus Nb (this study).
Chapter - 4 - Geochemical Stratigraphy - 119
90 -r-------------------- ~
80
70
Dominion
60 GroupRietgat and Basic Lavas
Goedgenoeg Klipriviersberg Group
Formations
50
...........................................................................
40
Allanridge Formation
30
20
Dominion Group Porphyries
10 Makwassie
Formation
o 2 4 6 8 10 12 14 16 18
TilP
Figure 4.17 Ti/P versus Ti/Zr Ventersdorp Supergroup discrimination diagram
(after T. B. Bowen, 1984)
Chapter - 4 - Geochemical Stratigraphy - 120
0.35~---------------------------------------- ~
0.30-
Makwassie
Formation
0.25- Dominion
Group
Porphyries
0.20-
-0.... Allanridge ."' '0'-N ; Formation • •• Rietgat &
0.15- •• Goedgenoeg... Formations~
Klipriviersberg . .'
0.10- Group
" .....~ ....
. • to·
.. ~ 0.;.tI'. ~.•.. ./ $.~~."
0.05- Dominion Group Basic Lavas ~
0.00-+---.--I----I.--------rl-----y--I--r--I----,I----rl--'--~___'i
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40
PlTi
Figure 41.18 Pffi versus ZrfP Ventersdorp Supergroup discrimination diagram (after
T. B. Bowen, 1984)
41.3.3 Multivartate Statistics.
The preceding paragraphs have demonstrated that adequate geochemical
discrimination between strati graphic units may be derived by bivariate means. One
. may argue however that because rocks are multi-element systems it is desirable to
employ more than two such variables simultaneously in a scheme of classification. It
was to this end that Discriminant Function Analysis was utilised. A brief review of
these techniques is included, though for further information specific to geological
applications, the reader is referred to Davis (1973), Le Maitre (1982) and Pearce
(1975).
Chapter - 4 - Geochernical Stratigraphy .. 121
4.3.3.1 Discrhnlnant Function Analysis (DFA).
DFA is a non-parametric statistical tool, which weights and combines variables into a
linear equation, forcing the variable to be as different as possible. OFA requires an
initial grouping of the data to be undertaken in order to define the functions, which in
the case of the present study has been defined on the basis of a plot of P20S versus Zr.
The purpose ofDFA is to perform the following functions:
G To discriminate between groups of observations on. the basis of a number of
variables.
o To classify observations and unknown samples into the correct groups on the basis
of the variables used to define the discriminant function.
In the case of the present study, two principal DFA techniques were applied and may
be defined as follows:
Stepwise Analysis:
A variable selection technique whereby a subset of the best-discriminating variables
are selected from a larger pool of variables. The logic behind stepwise analysis is to
select those elements from the data set which contribute most to discriminating the
respective strati graphic units.
Canonical Discriminant Analysis:
A dimension reduction technique In which new variables, known as canonical
functions, are derived from the original elemental variables. The purpose of this
Chapter - 4 - Geochemical Stratigraphy - 122
exercise is to derive canonical functions which best discriminate between strati graphic
units. These canonical functions may then be plotted graphically, thus generating
useful classification diagrams (it should be notecl however that such diagrams are
essentially a binary plot).
Table 4.1 Statistics and details of OFA of Rietgat Formation samples.
Discriminant 0/0 of CanonicallEigcnllvah.B.c Cumulative %
Function Variance Correlation
1 12.77877 48.45 48.45 0.9630288
2 9.36881 35.35 83.97 0.9505561
3 2.65362 10.06 94.03 0.8522318
4 1.10705 4.2 98.23 0.7248475
5 0.30216 1.15 99.38 0.4817132
6 0.1664 0.62 100 0.3757498
I After I SignificanceWilks-Lambda Chi-square DlF
Function I Level
0 0.0005996 1379.9663 0.0000 138
1 0.0082624 892.0643 0.0000 110
2 0.0856708 457.04721 0.0000 84
3 0.3130088 216.04344 0.0000 60
4 0.6595268 77.41928 0.0002 38
5 0.8588121 28.31016 0.0575 18
Chapter - 4 - Geochemical Stratigraphy - 123
Ancillary Statistics:
It should also be noted that a number of ancillary statistics were generated as a result
of DFA (see Table 4.l), the meanings of which are elucidated in the following
paragraphs:
e EIGENVALUE: An eigenvalue is produced by DFA for each discriminant function
and is a direct measure of the importance of each function in the discrimination of
groups. The higher the eigenvalue, the more important the discriminant function. In
general the eigenvalue is normalised and expressed in the form of a percentage.
e CANONICAL CORRELATION: the canonical correlation relates each discriminant
function to the variables used to define the groups. As such, it is a direct measure
of correlation between the data set and each discriminant function: the higher the
value of the canonical correlation, the stronger this relationship is.
Cl WILKS' LAMBDA: This is a test of the statistical significance of each discriminant
function. The Wilks' Lambda function is an inverse measure, so therefore a score
of zero is the highest possible value (ie no discriminatory power has been removed
by the discriminant functions). It follows that the value of lambda will increase as
each successive function is calculated. Theoretically, lambda should equal 1 at the
end of discriminant function analysis, this being due to the fact that all the
discriminatory power of the variables has been removed by the discriminant
functions.
Chapter - 4 - Geochemical Stratigraphy - 124
• CHI SQUARE is used as a test of significance, ie whether the distribution of data
differs from a predetermined theoretical 'normal' distribution. In the case of the
present study, the Wilks' Lambda function for each discriminant function was
converted into a chi-square value in order to test the statistical significance of each
discriminant function. Because chi-square is a sample-based statistic, it will vary
from sample to sample.
• DF (DEGREES OF FREEDOM) means the freedom to vary, and without recourse
to detailed mathematics, is difficult to define. In general however, the degrees of
freedom are the number of observations minus the number of estimates made from
them (Till, 1974).
4.4 Application of llJlFA to the Study Area
DFA was undertaken at the University of the Orange Free State on a Solaris 2.3
workstation using the SPSS 17 software package. Following the examination of a range
ofbivariate plots (as described in the previous section) it was decided that preliminary
grouping of the data should be based on a plot of P20S versus Zr (Figure 2.3). These
elements have the advantage of being immobile under a range of geochemical
conditions. The results of DFA are as follows:
Stepwise Analysis:
Table 4.2 illustrates the decreasing order of influence of elemental variables in the
discrimination of the strati graphic units of the Rietgat Formation. It should be noted
17 Statistical Package for Social Sciences.
Chapter - 4 - Geochemical Stratigraphy - 125
that the Wilks' Lambda value decreases with each successive step further signifying
the declining importance of each variable.
Table 4.2 Results of Stepwise Discriminant Analysis.
Variable Variable Variables Winks'
Step Entered Removed Included Lambda
1 P20s none 1 0.15641
2 Zr none 2 0.02042
3 Ti02 none 3 0.00777
4 Cr none 4 0.00417
5 Al203 none 5 0.00287
6 y none 6 0.00218
7 Ba none 7 0.00181
8 Na20 none 8 0.00157
9 CaO none 9 0.00136
Canonical Discriminant Analysis:
With reference to Table 4.1, it may be seen that functions 1 and 2 are the most
important of all the functions in terms of discriminating capacity since they have the
highest eigenvalues and relative percentages. The low initial Wilks' Lambda value, as
well as after Wilks' Lambda after the first function indicates that the variables used
have a high discriminatory power, Table 4.3 indicates that only 9 of the 194 samples
included in the analysis were misclassified - equal to -4.6% of the total samples. This
indicates that DFA is extremely accurate and can be used with confidence. Mis-
classified samples have been interpreted as having originated from near-unit contacts;
Chapter - 4 - Geochemical Stratigraphy - 126
altered zones or as being representative of localised geochemical facies variations. A
diagram representing the results of OFA is presented in Figure 4.19, on which groups
(units) are represented as fields and group centroids as asterisks.
Table 4.3 Results of classification by OFA.
Predicted Group Membership
of -r"Actual Number
Group Group 1Cases Group 2 Group 3 Group 4 Group 5
Group 1 72 69 2 1 0 0
95.8% 2.8% !.4% 0.0% 0.0%
Group 2 28 4 24 0 0 0
!4.3% 85.7% 0.0% 0.0% 0.0%
Group 3 63 0 0 63 0 0
0.0% 0.0% 100.0% 0.0% 0.0%
Group 4 7 0 0 0 7 0
0.0% 0.0% 0.0% 100.0% 0.0%
Group 5 24 0 1 1 0 22
0.0% 4.2% 4.2% 0.0% 91.7%
4.5 Application of DFA outside the Study Area
With reference to the canonical function coefficients in Table 4.4, it is possible to take
unknown samples and classify them in the aforementioned scheme. In order to put this
to the test, the Rietgat Formation data of T. B. Bowen (1984) was standardised, from
which the canonical functions were then calculated. When plotted (Figure 4.20) it may
be seen that only a weak relationship exists between the P20s-Zr-constrained units
(represented by numerals) and the fields derived by OFA of the Free State samples.
Chapter - 4 - Geochemica! Stratigraphy - 127
N (J)
r ~
z ou
:J 0::::
.....
lt) 5
U
C
::J
u,
..-
C
1'0
o oCE
°oCen
(5
~
occ:
'1
VV o
1'0
M
IVr----T~~------r_----~------~r~-;-.-----+------r----~I o,
lt)
,
1/). I/) o o I/), ,
Figure 4.19 Generalised Discriminant Function Plot for the Study Area.
Chapter - 4 - Geochemical Stratigraphy - 128
Table 4.4 Canonical Discriminant Function Coefficients
Standardizcd* Unstandardizcd*
Discriminant '. '_'_'
Function 1 2 1 2
Si02 0.86059 1.07068 0.24009 0.29870
Ti02 -0.89277 1.97147 -5.89768 13.02357
AI203 0.38393 -0.12659 0.39944 -0.13171
Fe203 0.2883 0.75708 0.14417 0.37858
MnO 0.03321 -0.24076 1.17100
MgO -8.489420.23366 0.12842 0.22023 O. i2iC4
CaO 0.49629 0.85362 0.19769 0.34002
Na20 0.43304 0.08018 0.39986 0.07403
K20 0.19167 -0.09458 0.20993 -0.10359
P20S 1.64842 -0.91922 25.64888 -14.30268
Rb 0.18468 -0.00422 0.00582 -0.00013
Ba -0.19209 0.50297 -0.00028
Sr 0.000740.25243 -0.35154 0.00115
Zr -0.00160-0.63255 -1.14415 -0.02602 -0.04706
Nb 0.10123 -0.02394 0.02349
Ni -0.005560.20831 0.18328 0.00914
Zn 0.008040.01316 -0.02789 0.00040 -0.00086
Cr -0.23455 -0.32551 -0.00305 -0.00423
Cu 0.03599 -0.04856 0.00126 -0.00170
V 0.39743 -0.14698 0.01369
Y -0.00506-0.42866 0.08678 -0.12156
Co 0.02461
l 0.091121 -0. i45551 0.00904 -0.14445CONSANT 1 0, 0/ -26.61031 -14.10960
*CanOlllcal Discriminant Function Coefficient
A similar procedure was followed using 12 Ventersdorp Supergroup lava samples
collected from the T'Kuip hills during the course of this study. These samples were
first plotted in the style of T. B. Bowen (1984) to ascertain which samples were
Rie.tgat Formation provenance, a summary of which is presented in Figure 4.21. The
canonical functions were then calculated for these samples and are plotted on Figure
4.22. it may be seen from Figure 4.22 that although by no means conformable to the
Chapter - 4 - Geochemical Stratigraphy - 129
current model, the data displays a somewhat greater degree of coherency in and
clustering than is seen in the Bowen example.
10~-------,"~-"-------------------~---------------'~ 2N \
C
o <, UNIT 4 \
U
C 5- ~" \
:J
L-L \ \ ~"'-c 4..........__ 2f 1 UNIT2ccu
.EL: 0-
~ \5 1 ",
5 \ ,
o UNIT3 5 \ UNIT 5 I -,
(f)
o
cu 5: 4\1 I UNIT 1 ""
·oe -5- 1 \ \-_I '\oc 3oCU L---~
-10~-----------r-I-----/-/~~-T~----------~I----------~
-10 -50S 10
Canonical Discriminant Function 1
Figure 4.20 Discriminant Function Analysis applied to the data ofT. B.Bowen
(1984).
The moderate to poor correlation of this model outside its type area could indicate
either lateral geochemical heterogeneity; or perhaps localised geochemical variation in
the lavas. For instance, a minor adjustment of the Unit 3-Unit 5 boundary. in the
T'Kuip example could lead to an almost perfect classification of these samples
according to the type framework.
Chapter - 4 - Geochemical Stratigraphy - 130
90
80 -
70 -
Dominion
60 - Group
Basic Lavas
Rietgat and Klipriviersberg Group
50 - Goedgenoeg
-L.NF-
.. Formations
. ............................................................................40 - ,.
~
Allanridge Formation
30 -
20 -
...................
Dominion Group Porphyries
10 - Makwassie
Formation •
0 I I I I I I I I
0 2 4 6 8 10 12 14 16
Ti/P
Rietgat & Dominion Group Klipriviersberg
Goedgenoeg Porphyries Group
Formations
COMPONENT SAMPLES:
TKlIl, TKl/3, TKlIIA, TK1/IB, TK2/1, TK2/l A,
TK1/4A, TK1I5, TK2/2A, TK2I2B, TK2/1B.
TK1I5A, TKl/5B, TK2I2C, TK2I2D.
TK1I6, TK2/2,
TK2/2F, TK2I2G,
TK2/2H, TK2/2I.
Figure 4.21 Above - Classification of Ventersdorp Supergroup lava samples from
the T'Kuip Hills (After T. B. Bowen, 1984); Below - Summary of the aforementioned
samples as per T. B. Bowen (1984) classification scheme.
Chapter - 4 - Geochemical Stratigraphy - 131
1DI~------~?~'"-,-------------------\'--------------'
N
c
o <, UNIT 4 \
1c:5 - ~ -\::JU. \ <,<,<; t
+J \
C
cu \ ......__ -, UNIT2c
.EL: 0-
33~. '\
U UNIT3 \ UNIT 5 I -,
Cl) 55
o 5
5
5 '\ I UNIT 1 "'"
·~ë -5-
oc
oCU )__IL---~"
-1D~-----------~,-----/-/~~~----------~----------~
-10 -5 0 1 10
Canonical Discriminant Function 1
Figure 4.22 Discriminant Function Analysis applied to the data from T'Kuip (this
study).
4.6 Discussion and Conclusions
This chapter has aimed to determine whether the lavas of the Rietgat Formation can be
subdivided on the basis of their geochemistry. The application of univariate statistics
to this problem failed to highlight any clear trends. Although bivariate analysis yielded
sufficient between-unit clustering of data, it was considered desirable to employ
multivariate statistical methods in order to analyse all of the elemental variables
simultaneously. This technique proved to be of very great accuracy in the type area,
though regrettably its application outside the type area failed to elucidate any
unequivocal correlation. It is however possible to conclude that a degree of lateral
Chapter - 4·· Geochemical Stratigraphy - 132
geochemical homogeneity exists in the study area. The fact that only moderate to poor
correlations may be made between the study area and outlying occurrences of the
Rietgat Formation indicates a higher degree of lateral geochemical heterogeneity at a
larger scale.
It is also pertinent and in a sense vindicating to note that, according to stepwise
analysis that the most powerful discriminating variables are P20s and Zr - ie the same
variables upon which the pre-DFA grouping was originally based (Figure 2.3).
Chapter - 4 - Geochemical Stratigraphy - 133
CHAPTER 5: GEOCHEMICAL CLASSIFICATION, MAGMATIC AFFINITY
TECTONIC SETTING AND PETROGENESIS.
5.1 Introduction,
The main objective of the following chapter is to classify the lavas of the Rietgat
Formation on the basis of their geochemistry. Conventional techniques and parameters
have been used to constrain the magmatic affinity, tectonic setting, petrogenetic
setting, petrogenesis and ultimately the source rocks of the Rietgat Formation. It is
pertinent to note that in addition to geochemical criteria, any model aimed at
explaining the geochemical evolution of the Rietgat Formation must also consider the
lithological and petrographic characteristics described in earlier chapters. Other
important considerations include the degree and scale of lateral geochemical
homogeneity óf the lavas and the virtual absence of sediments in much of the
succession.
5.2 Previous Work.
Many authors have identified the fact that igneous rocks may be classified in terms of
their generic name, magmatic affinity and tectonic setting on the basis of their
geochemical composition. Leading research and modelling to this end has, in recent
decades, included studies by Irvine and Baragar (1971), Pearce and Cann (1973)
Middiemost (1975), Cox et al. (1979) and Le Maitre (1989). In subsequent years, the
models developed by the aforementioned authors have been applied to numerous
. igneous provinces throughout the .world with the intention. of elucidating the
palaeotectonic setting, magmatism and petrogenetic aspects of these igneous suites.
Chapter - 5 Tectonic Setting and Petrogenesis - 134
A number of studies have attempted to constrain the geochemistry, mag'matic affinity,
tectonic setting and petrogenesis of the lavas of the Ventersdorp Supergroup. M. P.
Bowen (1984) examined the geochemistry of the Witwatersrand Triad volcanic rocks
in the Klerksdorp area with a view to determining their petrogenesis. Marsh et al.
(1992), Linton (1992) and Winter (1995) have investigated the geochemistry of the
Klipriviersberg lavas in the vicinity of Klerksdorp. These studies have involved both
the geochemical and magmatic characterisation of the Klipriviersberg Group as well
. as the clarification of the tectonic environment in which these lavas were extruded ..
Meintjes (1998) examined the geochemistry of the Makwassie and Goedgenoeg
Formations between Klerksdorp and Allanridge. In his study, Meintjes sought to
model the geochemical evolution of this lava series and to define the nature of the
source from which it was derived. Schweitzer and Kroner (1985) and Crow and
Condie (1988) have attempted to model the petrogenesis of the Ventersdorp
Supergroup as a whole, using a variety of geochemical techiques. The work of these
authors and others will be considered in a petrogenetic context at a iater stage in this
chapter. Very little investigation specific to the geochemistry and petrogenetics of the
Rietgat Formation have been undertaken: it is therefore the purpose of this chapter to
constrain the geochemical affinities of this lava series.
5.3 Geochemical Classification of the Rietgat Formation.
5.3.1 Application of Geochemical Discrimination Techniques
The previous section alluded to the fact that a number of discrimination procedures
exist whereby igneous rocks may be geochemically classified according to their
Chapter - 5 Tectonic Setting and Petrogenesis - 135
generic name, magmatic affinity and tectonic setting. Although a very wide range of
discrimination diagrams are available to choose from, only those displaying the most
explicit distribution of data are chosen for inclusion in this study. For a
comprehensive review of such discriminatory procedures,' the reader is referred to
Rollinson (1993), Chapters 3-5. "
5.3.1.1 Discrimination according to generic name
Winchester and Floyd (1976, 1977) have proposed a series of diagrams based on HFS
(High Field Strength) elements which discriminate between basic and intermediate
rocks. From a plot ofNbIY versus Zr/Ti02 (Figure SJ) it may be seen that the lavas of
the Rietgat Formation range from rhyodacite/dacite (Units 1 and 2) through andesite
(Units 4 and' 5(8) to basaltic andesite (Unit 3) in terms of their composition. This
system of classification was chosen in favour of the TAS (Total Alkalis versus Silica)
diagram of Le Maitre (1989) since it is more appropriate to highly altered terranes:
whereas alkaline metallic oxides are of high mobility in aqueous solutions, the HFS
elements are of relatively low mobility and are probably therefore more representative
of primary igneous processes.
5.3.1.2 Discrimination According to Magmatic Affinity
According to the ternary system Na20-K20-FeO(total) (or AFM diagram) of lrvine and
Baragar (1971), the lavas of the Rietgat Formation display a tholeiitic to calc-alkaline
affinity (Figure 5.2). This is applicable to all units, with the exception of Unit 2, which
displays a calc-alkaline affinity. Although one of the more commonly used diagrams
18 It was found that Units 4 and 5 showed extremely close coherency with regard to the discrimination
techniques used in this chapter and have, as such, been plotted as a single field.
Chapter+ 5 Tectonic Setting and Petrogenesis - 136
in the discrimination between tholeiitic and calc-alkaline basalts, the so-called AFM
diagram (Alkalis - Fe(tot)- MgO) does have certain shortcomings. One such problem is
that in most rocks the AFM parameters make up less than 50% of the oxide weight
percentage, so 'ft could be argued that the diagram is not truly representative of the
whole rock (Wilson: 1989). The main use of the AFM diagram is however to highlight
data trends which, may ultimately lead to the identification of a rock series.
In contrast to Figure 5.2, all of the samples on Figure 5.3 (Irvine and Baragar, 1971)
plot within the sub-alkaline (tholeiitic) field. The discrepancy between the two Irvine
and Baragar diagrams is attributed to the effects of alteration processes, such as
alkaline metasomatism. It should also be noted that in the ternary AFM system, the
variables are normalised to 100%, which may also affect the accuracy of the
technique.
5.3.1.3 Discrêmmation Aceerding to Teemnic Setting
Using the ternary system Zr/4 - Nbx2 - Y (Figure 5.4), Meschede (1986) was able to
identify the tectonic environment in which basaltic rocks were emplaced. When
applied to the present study, it may be seen from this diagram that the lavas of the
Rietgat Formation are of within-plate origin and moreover range between alkaline and
tholeiitic affinity, thus concurring with the system of Irvine and Baragar (1971)
discussed in the previous section. One point of caution that should be considered with
regard to this method is that it relies on the accurate measurement of Nb, which -
according to Rollinson (1993) - is difficult to obtain for concentrations below 10ppm
.. by means of XRF. Since the Nb concentrations observed in the study samples were in
Chapter - 5 Tectonic Setting and Petrogenesis - 137
the order of 10-20ppm, the discrimination technique of Meschede (1986) can therefore
be applied with confidence.
Pearce and Norry (1979) investigated the reasons for variations in the ratio of Zr/Y
and Ti/Y and concluded that they are probably a function of source heterogeneity.
Using a plot of Zr versus Zr/Y (Figure 5.5) the authors were able to discriminate
effectively between basalts from different tectonic settings. According to this
technique, it may be seen that the study samples classify as within-plate basalts. It is
also noted that Unit 3 plots as a distinct field on this diagram, possibly signifying
source chemistry variation or a subsequent modification process such as fractional
crystallisation or contamination.
Further evidence to support the classification of the Rietgat Formation lavas as calc-
alkaline basalts may be seen in Figures 5.6 and 5.7. These diagrams are, however,
intended for use in conjunction with a composition in the range of 20% > CaO +MgO
> 12% (Pearce and Cann, 1973). Since the study samples fall either within the
lowermost portion of, or outside this range, this technique has been applied with
extreme wariness. Additionally, Pearce and Cann (1973) indicate that the YlNb ratio
for the samples should be < 1.0 in order to be applied to this model. Although varied,
this ratio can reach elevations of up to 3 for the study samples, which may account for
the data points which plot outside the given fields in Figures 5.6 and 5.7.
Chapter - 5 Tectonic Setting and Petrogenesis - 138
Phonolite
Rhyolite
Trachyte
o 0.1 Rhyoda_c_ite/Dacite~ --- -
N -------
Andesite _________t_:~___
0.01 / Basaltic
Basaltic Andesite /,/' Nepelinite
----------------" Alkaline Basalt
Sub-Alkaline Basalt
0.001
0.01 0.1 10
NblY
Figure 5.1 Classification scheme for rocks of basaltic to intermediate composition
(after Winchester & Floyd, 1977, Figure 6).
FeO·
/ \
Calc·Alkaline
MgO
Figure 5;2 Discrimination diagram for basaltic rocks ofTholeiite/Calc-Alkaline
affinity (after Irvine and Baragar, 1971, Figure 2).
UNITS4&5 UNIT3 --- UNIT 2 ••••••••• UNIT 1 ---
Chapter - 5 Tectonic Setting and Petrogenesis - 139
20
18
16
14
;g-
o
112
0 10 Alkaline-2
+
0ro
z 8
6
4
2 Sub-Alkaline
0
3L5----4~0----4~5----5~0----~55----~6~0--~6~5----7LO----7~5----8~0--~851
Si02 (wt%) !
Figure 5.3 Discrimination diagram for basaltic rocks ofTholeiite/Calc-Alkaline
affinity (after Irvine and Baragar, 1971, Figure 3).
Nb·2
Within Plate Alkaline Basalts: A,. A2
Within Plate Tholeiites: A2•C
P·type MORB: B
N·type MORB: 0
Volcanic Arc Basalts: C. 0
Zr/4 y
Figllll!"e 5.4 Discrimination diagram indicating the tectonic affinity of basaltic rocks
(after Meschede, 1986, Figure 1).
UNITS 4&5 UNIT3 --- UNIT 2 ••••••••• UNIT 1 ---
"
Chapter - 5 Tectonic Setting and P'~trogenesis - 140
r-«
20 r---------------------------------------------------~
A - Within Plate Basalis
B - Island Arc Basalis
10 C - Mid-Ocean Ridge Basalis
B
C
10 100
Zr(ppm)
Figure 5.5 Discrimination diagram indicating the tectonic affinity of basaltic rocks
(after Pearce & Norry, 1979;Figure 3).
Ti/100
OFB - Ocean Floor BasalIs.
lAB - ISland Arc Basalis
CAB - Cale-Alkaline Basalts
Zr Sr/2
Figure 5.6 Discrimination diagram indicating the petrological and tectonic
affinities of basaltic rocks (after Pearce & Cann, 1973).
UNITS 4&5 UNIT3 --- UNIT 2 UNIT 1 ---
Chapter - 5 Tectonic Setting and Petrogenesis - 141
,';
Ti/100
Within Plate Basalts: D
Ocean Floor Basalts: B I
Low-Potassium Tholeiite: A, B i
Calc-Alkaline Basalts: B, C I
..,.. ....
Zr Y'3
lFigmre 5.7 Discrimination diagram indicating the petrological and tectonic
affinities of basaltic rocks (after Pearce & Cann, 1973)_
, ,
FeO'
1 - Spreading Centre Island
2 - oroqenlc
3 - Ocean Ridge and Floor
4 - Ocean Island
5 - Continental
4
3
MgO
Figure 5.8 Discrimination diagram indicating the tectonic provenance of silicic
igneous rocks (after Pearce et al:, 1977, Figure 1). NB. Unit 4 plots outside this
diagram
,UNITS 4&5 UNIT3 --- UNIT 2 •........ UNIT 1 _
Chapter- 5 Tectonic Setting and Petrogenesis - 142
10'5 r---------------------- __--,
LKT • Low Potassium Tholeiites
OFB· Ocean Floor Basalts
Êa.
.9: 10" ~--~
i= ~D
OFB
LKT
10 100 1000
Cr (ppm)
Figure 5.9· Discrimination diagram indicating the tectonic affinity of basaltic rocks
(after Pearce, 1975).
Pearce et al. (1977) used the system MgO - FeO(total)- AhO) as a means by which to
determine the tectonic setting in which sub-alkaline rocks were, emplaced. It may be ..._
seen from Figure 5.8 that the study samples are centred on the field for continental
origin. The usefulness of this diagram is restricted due to the mobile nature of the
major oxides in basaltic rocks. Pearce (1976) has furthermore demonstrated that AhO)
and MgO are mobile during greenschist facies metamorphism - the paragenesis of
which may be seen in the rocks of the Ventersdorp Supergroup. Another factor worthy
of consideration is the extent to which basalts may transgress fields on the diagram as
a result of crystal fractionation. The aforementioned processes may account for the
incursion of the study sample data points into fields 1,2,3 and 4 on Figure 5.8.
Chapter - 5 Tectonic Setting and Petrogenesis - ,143
A plot of Cr against Ti (after Pearce, 1975; Figure 5.9, this study) suggests that the
study samples are of ocean floor composition, somewhat contradicting the evidence
for continental derivation presented thus far in this section. This diagram has therefore
been regarded with caution in view of the overwhelming evidence in favour' of a
continental origin for the lavas.
5.3.1.4 Notes of Caution with regard to DnsCIl"nminnatioBDlliagrams.
It is considered pertinent to note that the following considerations should be made
when interpreting discrimination diagrams:
e The effects of data 'straddling' field boundaries may be attributed to geological
reasons - for example it is possible that a continental flood basalt may sample a
wide variety of crustal contaminants en-route to the surface, thereby giving rise to a
wide range of compositions.
e Discrimination diagrams should never be used uncritically, ie the effects of
fractionation and element mobility should be borne in mind. Such an approach has
been adopted in this study.
• Caution is required when discrimination diagrams are used in conjunction with
ancient rocks. It is contendable that the composition of the mantle has changed
with time and was less fractionated earlier in the history of the earth (Pearce et al.,
1984). Higher mantle temperatures in the Archaean may have given rise to higher
degrees of melting, the consequence of which could be a movement of the field
Chapter - 5 Tectonic Setting and Petrogenesis - 144
boundaries on the discrimination diagrams. It is also important to consider the fact
that at 2.7 Ga, plate tectonics of Phanerozoic affinity may not have been applicable.
5.4 Petrogenesis.
This chapter has thus far endeavoured to classify the lavas of the Rietgat Formation
according to published parameters. It has been established beyond doubt that
compositional variations exist between the individual lava units of the Formation. The
remainder of this chapter seeks to evaluate the geochemical processes responsible for
these variations, as well as the possible nature of the source from which the Rietgat
Formation was derived. Computer-based modelling was employed to this end and has
been used to test large numbers of fractional crystallisation and mixing models. Given
.the wide array of discrimination and data-presentation techniques employed in this
and foregoing chapters, it has been possible to propose a tectono-petrogenetic-
strati graphic model for the Rietgat Formation, which is presented at the end of this
chapter.
5.4.1 Process Identification,
An important factor in the understanding of the genesis of lavas is the identification of
any samples which represent primary melts from the upper mantle. Such magmas
should be unmodified by fractionation processes and in equilibrium with the
composition of the mantle. Magnesium numbers have been used as an indicator of
primary mantle characteristics and have been calculated for the lavas of the Rietgat
Formation (Table 5.1). For an explanation regarding magnesium numbers, the reader
Chapter - 5 Tectonic Setting and Petrogenesis - 145
is referred to Hughes and Hussey (1976, 1979). Given the fact that mantle magnesium
numbers are in the range of 68-75 (Green and Ringwood, 1976) it is evident that the
lavas of the Rietgat Formation are far removed from a primary mantle composition
and that a high degree of geochemical evolution has taken place. The inferred nature
of the process(es) responsible for the differentiation of the lavas of the Rietgat
Formation are outlined in the following paragraphs.
Table 5.1 Minimum, maximum and average magnesium-numbers for the lava') of
the Rietgat Formation.
Unit Value Mg Number
Average 29.25
5 Minimum 37.30
Maximum 17.65
Average 28.12
4 Minimum 13.67
I Maximum 35.48
Average 3l.71
3 Minimum 19.52
Maximum 39.49
Average 24.86
2 Minimum 20.76
Maximum 27.96
Average 29.01
1 Minimum 2l.29
Maximum 35.92
Chapter - 5 Tectonic Setting and Petrogenesis - 146
5.4.2 Identification of variation and trends in elemental data.
At first sight the geochemical data from the Rietgat Formation appear to show a near-
incomprehensible variation in the concentration of individual elements. Given the
assumption that these rocks are genetically related, it is necessary to apply a
geochemical technique which rationalises the variables and facilitates the
identification of any trends. The most commonly used means to this end is the
variation diagram. Originally used by Harker (1909), this is a simple two-dimensional
scatter plot on which two variables (one of which is usually Si02) are plotted against
one another and upon which linear trends may be observed in the data.
5.4.2.1 Bivariate plets of selected oxjde variables.
A range of bivariate plots (Figures 4.1-4.16) were presented in Chapter 4, the purpose
of which was to identify geochemical grouping of data with respect to stratigraphic
units. Upon closer inspection, within-unit linear trends may be identified on the same
diagrams: the reader is referred to Figures 4.1-4.4, which serve as examples.
Such trends on variation diagrams may occur as a result of the addition of crustal
material to a melt, magma mixing or due to the incremental addition of new partial
melt material to the existing magma. Fractional crystallisation is also an important
process in the evolution of igneous rocks and may also be responsible, at least in part
for the disjointed linear trends seen on the variation diagrams.
Although the procedure of Harker (1909) was followed, whereby all of the major
oxides were plotted against Si02 and MgO, the variation in these two oxides is too
Chapter - 5 Tectonic Setting and Petrogenesis - 147
slight to highlight any clear trends in the data. Hence in this case, the application of
major oxide data alone in the characterisation of the lavas is not possible. The
subsequent sections illustrate the importance of trace element data to the
understanding of the evolution of the Rietgat Formation.
5.4.2.2 Normalized multi-element diagrams.
Multi-element diagrams are of particular use in the depiction of basalt geochemistry.
They display a wide range of elements and consequently show a greater number of
peaks and troughs representing the relative enrichment and depletion of different
groups of elements. The elemental data used in the construction of the so-called
'spidergram' (Figure 5.10) have been normalised to a chondri tic meteorite reference
standard. Chondrites were chosen for this purpose, since they are thought to represent
unfractionated samples of the solar system dating from original nucleosynthesis. The
normalisation values employed to this end are those of Taylor and McLennan (1985)
and are presented in Table 5.2.
The remainder of this section aims to identify and explain the elemental trends present
on the spidergram and to make inferences regarding the nature of the source region
from which the lavas were derived. Regrettably, REE data for Units 2 and 3 were
unavailable at the time of writing.
Chapter - 5 Tectonic Setting and Petrogenesis - 148
Table 5.2 Chondrite Normalisation Values used in this study (after Taylor and
McLennan, 1985).
Chondrite Chondrite
Element Normalization Element Normalization
Value Value
K 854 Ti 654
Rb 3.45 Dy 0.381
Ba 3.41 Y 2.25
Nb 0.375 Ho 0.0851
La 0.367 Er 0.249
Ce 0.957 Tm 0.0356
Sr 11.9 Yb 0.248
Pr 0.137 Lu I 0.0381
Nd 0.711 Sc 8.64
Zr 5.54 V 85
Sm 0.231 Zn 462
Eu 0.087 Cu 168
Gd 0.306 Ni 16500
Tb 0.058 Cr 3975
Rare Earth Elements
The REE'SI9 are of particular value in igneous petrology in that they are the least
soluble of the trace elements, being relatively immobile during metamorphism,
weathering and hydrothermal alteration. Hence, one may assert with a degree of
confidence that REE patterns are representative of the unaltered rock.
It is observed (Figure 5.10) that Units 1, 4 and 5 are relatively enriched in LREE's
(La, Ce, Pr and Nd).
19 All REE analyses were undertaken at the University of Cape Town. A summary of the analytical
procedure involved to this end is presented in Appendix I.
Chapter - 5 Tectonic Setting and Petrogenesis - 149
Eu anomalies are generally controlled by the feldspar minerals, this element being
highly compatible in both plagioclase and potassic varieties of the mineral. Hence, the
negative anomaly with respect to Eu (Figure 5.10) reflects the removal of feldspar
from the melt. Although highly prevalent in felsic melts (Rollinson, 1993), this trend
is less pronounced in the study samples due to their more basic to intermediate
affinity. The very close conformity in elemental variation between Units l , 4 and 5
could be interpreted as being indicative of consanguinity.
Table 5.3 REE analytical data
MA1-4 S4-10 S4-15 S4I-3 MAl-8 MA1-20 MA1-1
Unit 5 5 5 4 4 1 USH
La 36.60 59.50 57.70 62.10 70.60 68.20 8.57
Ce 80.00 120.00 117.00 128.00 142.00 139.00 18.50
Pr 10.90 15.80 15.50 16.80 19.10 18.30 2.25
I II I INd 45.50 63.00 I 62.00 66.40 77.00 ! 7l.50 9.21
Sm 8.85 11.20 11.10 11.20 13.60 12.70 1.96
Eu l.43 2.54 2.70 2.09 3.21 2.78 0.50
Gd 7.97 9.22 9.01 6.12 10.60 9.97 1.94
Tb 1.16 1.28 1.25 1.08 1.46 1.38 0.33
Dy 6.99 7.44 7.25 6.18 8.39 8.00 2.24
Ho 1.36 1.42 1.40 1.25 1.60 1.56 0.49
Er 3.86 3.95 3.95 3.72 4.50 4.43 1.49
Tm 0.53 0.54 0.54 0.53 0.61 0.61 0.22
Yb 3.41 3.54 3'.52 3.56 3.98 4.09 1.50
Lu 0.51 0.52 0.52 0.54 0.59 0.60 0.22
Chapter - 5 Tectonic Setting and Petrogenesis - 150
Figure 5.10 Chondrite-Normalised Multi-Element variation diagram.
1,000 ,~ --1
100 -
llC"'U.. lVII
- - - Unit 1
--Unit4
o -, --- Unit5
K Rb Ba Nb La Ce Sr Pr Nd Zr Sm Eu Gd Tb Ti Dy Y Ho Er Tm Yb Lu Sc
Trace Element
Depletion of the HREE's (Er, Tm, Yb and Lu) relative to the LREE's may be caused
by the fractionation of olivine, garnet, hornblende, orthopyroxene and ciinopyroxene
into which the HREE's are highly compatible. In general, the more compatible
elements to the right-hand side of the spidergram are less enriched due to the
combined effects of fractional crystallisation and partial melting. This gives the
spidergram its characteristic downward slope towards the right. It must therefore
follow that the lavas of Units 1,4 and 5 cannot have been derived from a source rich
in olivine, garnet, hornblende, orthopyroxene or clinopyroxene.
In the case of the clastic sediments, the most important factor governing REE
characteristics is. provenance. Because the REE's are insoluble under aqueous
conditions their presence in sedimentary rocks may instead be a function of the
Chapter - 5 Tectonic Setting and Petrogenesis - 151
particulate matter from which the rocks are derived. It follows therefore that REE
characterstics of the sediment are representative of the geochemistry of their source.
Furthermore, diagenetic processes have little influence on the REE characteristics of
sedimentary rocks, since very large amounts of fluid would be required to effect this.
The REE characteristics of the USH conform closely to those of the lavas, despite
being an order of magnitude lower in terms of concentration. It is concluded that the
sediments were derived locally - ie from the underlying lavas - thus explaining the
coherent REE trend seen between the two lithologies. The lower concentrations of
REE's in the sediments relative to the lavas has been attributed to the high quartz
presence (as has been deduced petrographically in Chapter 3) which may have had a
diluting effect on elemental abundancies (Wilson, 1989).
Trace Elements
With respect to Figure 5.10 the LIL20 elements (Rb, K, Ba and Sr) are relatively
enriched in comparison to the HFS elements (Y, Zr, Nb and Ti). Since the LILE's are
highly mobile at crustal levels under fluid conditions, it is realistic to assume that the
LILE compositions of the Rietgat Formation are not representative of the original bulk
composition of the series. This may be attributed to the fact that the lavas have
undergone both metasomatic and greenschist facies alteration, which are fluid-
orientated and hence are ideally suited to the mobilisation of the LILE's. It is however
possible to make certain inferences regarding petrogenesis of a rock based on its LILE
characteristics. For instance, Sr may substitute for Ca in plagioclase, which may
account for the negative anomaly seen (with respect to Sr) on the spidergram.
Similarly Rb and Ba may substitute for K in feldspar, hornblende and biotite. The
Chapter - 5 Tectonic Setting and Petrogenesis - 152
positive Ba and negative K anomalies may also be attributed to primary magmatic
processes, though it is just as likely that they are the product of a secondary fluid
event.
The abundance of certain elements may be strongly influenced by individual mineral
phases. This is particularly common among HFS elements, where magmatic processes
generally govern concentration. For example, a positive Zr anomaly may be attributed
to the presence of zircon phenocrysts in the lavas. P is highly compatible in apatite, so
it can be postulated that the- negative P anomaly is a consequence of apatite
fractionation. Since Nb is highly incompatible in continental crust, one could expect a
strongly negative anomaly with respect to this element to result from crustal
contamination. A weakly depleted trend is indeed visible from the spidergram (Figure
5.10) so it can-be inferred that crustal input was moderate during the petrogenesis of
the lavas (Rollinson, 1993). This topic will however be addressed in the following
section. The minor negative anomaly with respect to Ti is interpreted as signifying the
fractionation of ilmenite and/or titanomagnetite (Wilson, 1989). Since Y is highly
incompatible in basaltic melts but is readily accommodated by amphiboles, garnet,
sphene and apatite, it is suggested that a positive anomaly with respect to this element
could be indicative of an amphibole or sphene presence
20 Large Ion Lithophile (Elements)
Chapter - 5 Tectonic Setting and Petrogenesis - 153
100 .----------------------------------------------------------~
._- --- Unit 1
---Unit2
. Unit 3
10 .
- - - - - - Unit 4
------------Unit 5
Ê
a.
,e, 1
2 ~\.::::
-a
c "
.0c "
o " ,
::>2 "'\ ","I
o
0 0.1 " ,,'",~ #
0::
0.01 -
0.001 -
Sc Ti v Cr Mn Co Ni
Transition Metals
Figure 5.11 Chondrite-Normalised variation diagram for the Transition Metals .
. High concentrations of the transition metals (Zr, Figure 5.10; Ni and Co, Figure 5.11)
serve as good indicators of the derivation of parent magmas from a peridotitic mantle
source. Decreases inNi and to a lesser extent Co through a rock series are suggestive
of olivine, clinopyroxene or spinel fractionation. Both. Ni and Co show depletion on
the spidergram (Figure 5.11), corroborating the fact that some degree of fractionation
Chapter - 5 Tectonic Setting and Petrogenesis - 154
has taken place. An inconsistency does exist in that the Ni and Co abundancies do not
decrease directly with stratigraphic height.
Cu and Zn have been omitted from the spidergram since they may have been extremely
mobile during metamorphism, so therefore their concentrations probably do not
represent igneous values (Wilson, 1989) .
.The analysis of trace element data in this section has made it possible to conclusively
determine that both crystal fractionation and mixing/contamination processes have
played a role in the genesis of the lavas of the Rietgat Formation. Proposals regarding
the level of involvement of these processes are laid out in the following section.
5.5 Genetic Modelling.
Having postulated that crystai-liquid fractionation and a degree of mixing were :.~<r:o'
involved in the petrogenesis of the Rietgat Formation, it is desirable to clarify the role
of these processes in greater detail. To this end a plot of Ni against Zr was constructed
(Figure 5.12), upon which the .linear trends of all Platberg-age lava series were
superimposed.
It is the intention of the Ni-Zr plot to elucidate fractionation trends in igneous rock
series. The elements. Ni and Zr behave in inverse proportion to· one another during
crystal fractionation (Meintjes, 1998), the former becoming more depleted and .the
latter relatively enriched during this process. The main direction of the evolutionary
trends (deduced by reference to the relative stratigraphic juxtapositions of individual
'-
samples in borehole sections) of the units of the Rietgat Formation are indicated by
Chapter - 5 Tectonic Setting and Petrogenesis - 155
700
600 t~\"'
G
500 ,i ~
400 ~1. ,
E
0..
0.. ~ \
'-
N M, ~'
300 tJ ~ 5,@
_ _....
200 _ - (fI'3\iO(l
_- fol
__ (lfo.Ó~e ~\O(l'3ri
~~'3 e~~u 'Óe(l~ _
~(lO-ÓS e~~l->" --\-Ie(l »>
100
Klipriviersberg
0
0 100 200 300 400 500
Ni(ppm)
Code Description Source of data
(1)-(5) Rietgat Formation - Units 1-5 This study
Gm Goedgenoeg - rnafic
Gi Goedgenoeg - intermediate Meintjes (1998)
Gz Goedgenoeg - zircon-rich
Md-Mr Makwassie Formation This study
Figure 5.12 Plot of Ni versus Zr as an indicator of fractionation processes.
Chapter - 5 Tectonic Setting and Petrogenesis - 156
the bold arrows on the Ni-Zr diagram. In the case of Unit 1, a degree of oscillation
was evident in the down-profile Ni/Zr ratio. The overall trend is however that of
reverse fractionation, which has been indicated by a bold arrow. At certain localities,
the individual units display normal fractionation: a smaller arrow has been used to
denote this 'secondary fractionation' trend on Figure 5.12.
Data from the Goedgenoeg and Makwassie Formations (Meintjes, 1998) and the
Klipriviersberg Group and Allanridge Formation (data from the present study,
Appendix 3) have also been included on the Ni-Zr diagram with a view to
constraining the petrogenesis of the Rietgat Formation in the broader context of the
Ventersdorp Supergroup.
Having first assumed that the lavas of the Rietgat Formation are derived by Raleigh
fractionation, possible source materials were then modelled on the basis of their Ni-Zr
content using the NEWPET software programme. Given the large number of uncertain
variables and simplifying assumptions that are a feature of software packages such as
NEWPET, any modelling derived by such means should be treated tenuously. A
review of the KO'S21applied by these calculations is presented in Table 5.4. A range of
mantle compositions were subjected to up to 95% fractionation in an attempt to
determine whether such a fractionation event could be responsible for the generation
of the lavas of the Rietgat Formation. A garnet-bearing source was discounted due to
21 Ko's are distribution co-efficient, i.e. the rate at which any given elemental constituent will buffer
into any given mineral phase during fractional crystallisation (this study).
Chapter - 5 Tectonic Setting and Petrogenesis - 157
Col Col
C i-03
Col C ColCol "0 Col Col I...lo< ril ë ~
.C5ol lo<f e cCol "-ii. ue.s -Col ~ .~: -Col e.sCl.. Ccol Col Col :I r:::r:c e ë ril "0.~ ...... ...... ~ e e.s Col 'ë "0 Col -.: =E C ~s eCl.. Cl.. e 'Si! e.s ~ Col:I .c e.s :I.: ec E if e.s c 0' e.s e Cl.. Cl.. CJ!e s: ~ ;::::; ~ rJ1 -e IX 2e ~t: := = ~ U0 U
~
La 0.009 0.026 0.288 0.440 0.035 0.180 0.121 - - - - - - - - C/J
Cc 0.009 0.033 0.303 0.540 0.034 0.120 0.144 - - - - - - - - ~
Pr o0.010 0.042 0.341 0.750 0.033 0.097 0.188 - - - - - - - - .o..,
Nd 0.010 0.051 0.379 1.000 0.032 0.081 0.232 - - - - - - - - Q..
Sm S'0.011 0.079 0.476 1.490 0.031 0.067 0.541 - - - - - - - - (JO
Eu 0.011 .....0.099 0.354 1.500 0.036 0.340 0.623 - - - - - - - - o
Gd 0.012 0.126 0.561 1.700 0.030 0.063 1.190 - - - - - - - - ~
Dy 0.014 0.197 0.663 2.200 0.030 0.055 2.560 - - - - - - - -
Er Z0.019 0.355 0.706 2.100 0.034 0.063 4.240 - - - - - - - - m
Yb 0.023 0.470 0.719 1.400 0.042 0.067 5.730 - - - - - - - - ~
Lu 0.027 0.590 0.719 1.300 0.046 0.060 6.300 - - - - - - - - "m0o
~:r K 0.006 0.006 0.027 0.860 2.700 0.360 0.150 - - - - - - - - >-l
"0
ë..t, Rb 0.004 0.003 0.Q30 0.400 3.100 0.200 0.200 - - - 0.500 - - - -
Co/J
.Sr ~0.009 0.050 . 0.300 1.020 0.080 3.600 0.090 . - 0.200 - 1.000 100.00 5.000 - 1.300I
V...I., Ba 0.002 0.040 0.025 0.440 1.100 0.460 0.050 - 0.100 - 1.000 1.000 5.000 - 0.600
n Cr
~
3.100 10.000 20.000 3.000 12.600 0.040 0.100 - - - - - - - -o ".0..,s Ni 19.000 5.000 4.400 7.000 20.000 0.D40 0.800 - 10.000 10.000 - - 2.000 o:::s - -
o' Ti 0.Dl0 0.100 0.500 2.000 0.900 0.045 0.690 - - - - - - - -
r:/l Sc 0.220 1.200 3.200 4.200 2.000 0,040 6.500
~ - - - - - - - -
5' Yb 0.020 0.400 0.800 1.320 0.030 0.025 5.000 - 0.020 0.100 0.100 200.00 25.000 15.000 0.500 1
CICI
~ Nb 0.008 0.015 0.216 0.800 1.000 0.010 0.100 - 1.000 2.500 0.010 3.000 0.100 25.000 0.500:::s
0- Zr 0.010 0.020 0.420 0.500 0.600 0.010 0.600 - 0.500 0.800 0.010 6.500 0.700 0.900 0.500
-e
!..,l Mn 1.800 1.400 1.300 0.940 6.000 0.050 5.000 - - - - - - - -
o V 0.030 0.500 1.000 4.000 6.000 0.080 0.270 - - - - - - - -
CoICI:::s U 0.007 0.007 0.253 . 0.540 0.450 omo 0.100 - - - - - - - -
n~. Th 0.007 0.007 0.158 0.540 0.310 omo 0.100 - - - - - - - -
Cl> Ga 0.040 0.700 . 0.580 0.800 4.000 1.000 12.000 - - - - - - - -
VI
oe .. _----~--
700 ~------------------------------------------------~
_- Anhydrous Spinel Lherzolite 1 II
-- - Volatile-bearing Spinel Lherzolite/
600 - Spinel-facies Peridotite''
Spinel-facies Peridotite"
Spinel-facies Peridotite''
Spinel-facies Peridotite''
500 - Spinel-facies Peridotite
400 ....,.
..-..
er-
0..
0..
'-
N
300 -
200 - 95% crystal fractionationI
\
\ \
,
, \ \ ,
I \ \
100 - \ 'I \ \ \,
\\\\\ \\\" \ ',
",,".;.
'-.''"'-' --.
......._
--_,-- ---=-_ --- -===-- -= ===- =
O~------~I-------.I----__-~--;- :..I-:==:=-:-=:::=..o~...I...=,..,=...=..:.=_~===,_~I..===,=====~
-100 ' o 100 200 300 400 500
Ni (ppm)
Figure 5.13 Theoretical evolution by crystal fractionation of a range of mantle
materials using NEWPET elrving, 1980; 20'Reilly & Griffin, 1987; 73- Boyd et al.,
1997).
Chapter - 5 Tectonic Setting and Petrogenesis - 159
the enriched nature of the study samples with respect to the HREE's (see Section
5.4.2.2). The results of this exercise are presented in Figure 5.13, which clearly
indicates that even high degrees of fractionation of mantle material alone are
insufficient to give rise to the basaltic-andesitic-rhyodacitic rocks of the Rietgat
Formation. It is therefore likely that the only means by which the Zr concentrations
may reach the elevated levels seen in the study data is if the source of the Rietgat
Formation was enriched in Zr .
.The existence of an enriched mantle source for the Platberg Group lavas has been
documented by previous researchers (Schweitzer and Kroner, 1985; Crow and Condie,
1988): the enriched nature of the HFSE and REE in the Rietgat Formation are further
evidence in support of this assertion. Crow and Condie (1988) have furthermore noted
that such enrichments point to a separate source for the Platberg Group lavas, since
such values are difficult to obtain from fractionated Klipriviersberg source ..It should
be noted that in the absence of isotopic and more detailed REE· analytical data, the ,. .""
palaeo-tectonic environment and source rocks for the Rietgat Formation remain very
contentious.
5.6 A tectono-stratigraplmic-petrogellnetic model for timeevolution of the
Rietgat Formation .
.This section aims to combine and synthesise the findings of the foregoing chapters
into a model explaining the tectonic, stratigraphic and petrogenetic evolution of the
Rietgat Formation.
Chapter - 5 Tectonic Setting and Petrogenesis - 160
5.6.1 Tectonic Background
The prevalence of rifting during Platberg times has been extensively documented and
is also easily evidenced by field relationships. Burke et al. (1986) and Stanistreet.er al.
(1986) observed that the lavas of the Ventersdorp Supergroup were extruded into/a
series of NE-SW trending grabens and half-grabens. Debate exists as to ~the
./
mechanism responsible for the formation of the Ventersdorp basin and the
emplacement of associated volcanic rocks. Schweitzer and Kroner (1985) have
proposed that rifting may have taken place in response to an ascending mantle plume;
Burke et al. (1986) and Winter (1976) have both suggested that rifting/volcanism
occurred in response to the collision between the Kaapvaal and Zimbabwe Cratons
~2.6-2.7 Ga ago.
5.6.2 An 8-stage model for the development of the study area
In the light of the foregoing discussion, the following model has been proposed in the
explanation of the geology of the Rietgat Formation:
Stage 1
An extensional tectonic regime commencing in Kameeldooms time gave rise to the
development (jf a series of graben/half-graben basins (Figure 5.14). This phase of
structural evolution is akin to stage 2 of the 3-stage rift system as proposed by
Clendenin et al. (1988a). As has been mentioned, the regional tectonic framework
responsible for driving this rifting has in the past been attributed to an asthenospheric
upwelling or the collision of the Zimbabwe and Kaapvaal cratons. The continental
Chapter - 5 Tectonic Setting and Petrogenesis - 161
~USH
t:::::::~jUNIT 1
UNIT2
~UNIT3 RIETGAT FORMATION
~
~UNIT4
~UNIT5
féï~Wf:r:;lLSH (proximal/distal)
~ PILLOW LAVAS
FA'UL"i ...-\10~11~~O'\lY."s :II.I..d..i'c''''a0tc""""~"~"I"n<.",o.h.•
of movement)
(Key to Figures 5.14 - 5.21;followingpages)
signature of the lavas of the Rietgat Formation and the flood basalt affinity of the
antecedant Klipriviersberg Group (Marsh et al., 1992) is consistent with an
asthenospheric upwelling. Associated lithospheric thinning and the regional elevation
of geothermal gradients is proposed.
Chapter - 5 ...:T. ectonic Setting and Petrogenesis - 162
Figure 5.14 Stage 1 in the development of the study area: late Kameeldooms time
(key on page 162).
Figure 5.15 Stage 2 in the development of the study area: late Makwassie to LSH
times. (key on page 162)
Chapter+ 5 - Tectonic Setting and Petrogenesis - 163
Figure 5.16 Stage 3 in the development of the study area: final Makwassie and Unit .,.
1. (key on page 162)
E~
Figure 5.17 Stage 4 in the development of the study area: renewed structural
extension. (key on page 162)
Chapter - 5 - Tectonic Setting and Petrogenesis - 164
Figure 5.18 Stage 5 in the development of the study area: extrusion of Units 1 and
2. (key on page 162)
n
;:~
Figure 5.19 Stage 6 in the development of the study area: widespread extrusion of
Unit 3 lavas. (key on page 162)
Chapter- 5 - Tectonic Settin.~ and Petrogenesis - 165
Figure 5.20 Stage 7 in the development of the study area: contemporaneous
extrusion of Units 4 and 5. (key on page 162)
....... ,.
Figure 5.21 Stage 8 in the development of the study area: cessation of volcanism
and the deposition of the USH. (key on page 162)
Chapter - 5 - Tectonic Setting and Petrogenesis - 166
Stage 2
Extensional tectonism persisted into late Makwassie times (Minter et al., 1986),
during which basin development governed the distribution of the late-stage
Makwassie porphyries (Figure 5.15). The newly uplifted fault scarps gave rise to the
generation of large amounts of sediments in their vicinity, to form the LSH. Proximal
and distal facies variations in these sediments are most easily recognised by their
contrasting grain size: while the most proximal deposits comprise diamictites, the
more distal deposits are of an argillaceous nature.
Stage 3
Figure S.Iódisplays the final stages of extrusion of the Makwassie Formation, which
is concomitant to the extrusion of Unit 1. Given the close proximity of Unit 1 to the
Makwassie Formation on the Ni-Zr diagram - as well as its oscillatory to reverse
fractionation trend - it has been proposed that the relatively evolved lavas of Unit IM
may represent mixing between the remnant Makwassie residue and magma from a
new shallow crustal reservoir. Following the complete cessation of Makwassie
volcanism the new reservoir could have been periodically refluxed by pulses of partial
melt from the mantle, which undergo fractionation and ultimately extrusion. This so-
called RTF (Replenished, Tapped and Fractionated; O'Hara and Matthews, 1981)
system can give rise to the reverse fractionation trends seen in Unit 1. It is also likely
that APC (Assimilation and Fractional Crystallisation; De Paolo, 1981) processes
could be in operation which may be another factor contributing to the reverse
fractionation trend.
Chapter - 5 - Tectonic Setting and Petrogenesis - 167
Stage 4
The restricted distribution of Unit 2 in the study area may be due to a structural
control on its emplacement (Figure 5.17). It is therefore proposed that a phase of re-
activation of existing fault structures took place either prior to or during the earliest
stages of its emplacement. Such tectonism may have been the product of either
renewed extension or thermal subsidence triggered by fresh pulses of magma entering
the shallow crusta] reservoir.
Stage 5
It may be seen from the Ni-Zr plot (Figure 5.12) that Unit 2 is less evolved than Unit
1. It is proposed that the crustal reservoir in which the Unit 1 magma was ponded
underwent refluxing by magma derived .from a deeper level mantle reservoir (Figure.
5.18). Also, the final cessation of activity on the former Makwassie reservoir could
have reduced the potential input of more evolved material to the system. Unit 2 shows
a coherent crystal fractionation trend (Figure 5.12) suggesting that the replenishment
of the crusta I reservoir did not take place in this period, thus allowing fractionation
processes to operate undisrupted.
Stage 6
Figure 5.19 shows the widespread extrusion of the lavas of Unit 3. It is once again
envisaged that these lavas were derived by the refluxing of the same chamber from
which Units 1 and 2 were derived. Further evidence to support this theory may be
gleaned from the Ni-Zr diagram (Figure 5.12), which indicates that the starting
Chapter- 5 - Tectonic Setting and Petrogenesis - 168
composition of the Unit 3 series is of a less evolved composition than that of the
preceding Unit 2.
Stage 7
IUs proposed that Units 4 and 5 were emplaced concomitantly as is evidenced by their
contemporaneous/interdigitating relationship and geochemical similarity in the study
area (Figure 5.20). Figure 5.12 indicates that the composition of Unit 4 is more
evolved than that of Units 3 and 5. It is postulated that volcanism had begun to wane
by this stage in Rietgat times due to lower degrees of refluxing of the crustal reservoir.
Indeed a greater sedimentary presence in these units attests to the decline of
volcanism. It is possible that Units 4 and 5 evolved separately in the same chamber: a
non-turbulent refluxing event at the base of the chamber could give rise to a density
contrast, the result of which may be that the more evolved Unit 2 magmas rose
buoyantly to the top of the chamber where they continued to differentiate. Units 1 and
2 were then extruded via different conduits.
Stage 8
Figure 5.21 depicts the complete cessation of volcanism and the absolute dominance
of the sedimentary processes responsible for the deposition of the USH.
'\
5.6 Discussion and Conclusion
The foregoing chapter has demonstrated that the lavas of the Rietgat Formation may
be. classified according to their geochemical composition. Elemental data have also
Chapter - 5 - Tectonic Setting and Petrogenesis - 169
been used to model and constrain magmatic differentiation processes and source
regions.
It can be concluded that the lavas of the Rietgat Formation are derived from the partial
melting of an enriched mantle source. The resultant magma was then ponded at
shallower crustal levels where it underwent a combination of AFCIRTF processes
prior to extrusion, giving rise to the distinct geochemical units identified by this study.
Chapter - 5 - Tectonic Setting and Petrogenesis - 170
CHAPTER 6: SUMMARY AND PRESENTATION OF TYPE SECTION.
The following paragraphs aim to condense the findings of the foregoing chapters into
a synopsis of the most salient features of the Rietgat Formation.
6.1 General Characteristics and Lithology.
The rocks of the Rietgat Formation may be subdivided into a lower sedimentary
horizon (LSH), which is overlain by 5 geochemically distinct lava units - accordingly
named Units 1, 2, 3, 4 and 5. The uppermost unit of the Rietgat Formation is
sedimentary and has been termed the upper sedimentary horizon (USH). This system
of sub-division is an elaboration of the type stratigraphy for the Rietgat Formation as
envisaged by Winter (1976).
The thickness of the Rietgat Formation in the study area varies widely and the:
succession is at its most developed in the deepest of the Platberg-age grabens, where it
may attain a vertical thickness of more than 600m. The formation is laterally
widespread in the area of the Free State ·Goldfields and may also be correlated to
remote localities, such as the T'Kuip hills (Figure 2.2).
The lavas of the Rietgat Formation are typically fine-grained, greyish-green in colour
and variably amygdaloidal, with individual flows ranging in thickness from 6m to
over 300m. Flow tops are generally identifiable by their amygdaloidal affinity and in
many cases their higher degree of alteration. Thicker flows, although not by necessity,
Chapter - 6 - Summary & Type Section - 171
tend to exhibit a porphyritic tendency towards their centre and a vuggy presence
nearer their base.
6.2 Mineralogy and Petrography.
The mineralogy and petrography of the lavas is very similar throughout the whole . .f
succession, .varying only between rhyodacite, andesites and basaltic andesites. The
. primary composition of the lavas has been completely changed as a result of lower
greenschist facies burial metamorphism, to which the entire Ventersdorp Supergroup
was subjected. The resultant mineral assemblage in Units 1 to 5 comprise, in varying
proportions, a paragenesis of quartz, albite, chlorite, actinolite, epidote and calcite. It
is proposed that the chemical state of the lavas subsequent to metamorphism
represents that of the original magma compositions, i.e. the introduction or extraction
of elemental material was minimal.
The LSH and USH consist primarily of quartz and calcite, an assemblage which has
been interpreted as being a function of protolith. A degree of chloritisation has
however pervaded the sediments.
The alteration mineralogy manifests itself primarily as quartz and chlorite amygdale
fillings and varying degrees of chloritisation and epidotisation of the groundmass of
the lavas ..Alteration also gives rise to bleached, silicified and epidotised zones, which
occur principally in conjunction with flow tops and structural discontinuities, such as
faults.
Chapter - 6 - Summary & Type Section - 172
6.3 Geochemica! Stratigraphy.
Univariate, bivariate and multivariate data handling techniques have successfully
demonstrated that it is possible to stratigraphiêally subdivide the lavas of the Rietgat
Formation on the basis of their geochemistry. The application of a variety of such.
techniques has yielded consistent results (Figures 4.1-4.16). Adequate separation of
the units may be facilitated by simple inter-element relationships, particularly with
respect to immobile elements such as Ti, P, Zr, V and Nb. Multivariate statistical
techniques provided tighter constraint on the geochemical groupings and facilitated
the moderately positive correlation of sample data from T'Kuip with that of the study
area (Figure 4.22).
6.4 Magmatic Classifieation and Tectonic Setting.
Using conventional geochemical nomenclature (Chapter 5), the lavas of the Rietgat
Formation are classified as andesites, basaltic andesites and rhyodacites.·
Discrimination diagrams based on the variation of largely incompatible elements
indicate that the lavas are of calc-alkaline to tholeiitic affinity and were erupted in a .
continental plate-tectonic setting. Both field and geochemical evidence support the
theory that a rifting event took place during Platberg times.
Magnesium numbers indicate that the lavas of the Rietgat Formation do not represent
unmodified primary mantle melts. The modification of such. magmas is reflected in
the REE and trace element characteristics of the lavas, which suggest that a degree of
crustal contamination and fractional crystallisation have taken place.
Chapter - 6 - Summary & Type Section - 173
6.5 Petrogenesis.
It is proposed that the primary magmas of the Rietgat Formation were derived by the
melting of an enriched peridotitic mantle source. Upon ascent, these magmas may
have porided in the lower crust where they underwent AFC processes, thus affording
the magmas their continental signature. Further contamination may be attributed to
assimilation of wall-rock material from conduits during their ascent. Moreover, an
elevated geothermal gradient in the region resulting from litho spheric thinning could
also have resulted in the melting of crustal material and the subsequent contamination
of the magmas.
Field and geochemical evidence are consistent with the consanguinous development
of the Rietgat Formation, to which end it is proposed that the ponded magmas may
have undergone a periodic RTF process.
6.6 Proposed! Reference Section.
The stratigraphy of the Rietgat Formation is summarised in Figure 6.1. Since the
original type section R~ i (Winter, 1976; Figure 2.1, this study) for the Rietgat
Formation was unavailable at the time of writing, a composite reference section
involving boreholes NVTl and KFN2 is proposed. These sections have been chosen
on the grounds that they are the most geochemically and litho logically representative
profiles in the study area. An explanation of Figure 6.1 has not been included since it
is believed that this would amount to repetition of the annotated explanations
contained therein.
Chapter - 6 - Summary & Type Section - 174
RANGE TYPE
LITHOLOGY DESCRIPTION IN UNIT BORE
THICKNESS HOLE
Ouartzwacke, coarsening down from fine sand to grit. Dark
Ze. grey shaly intercatations commonly containing buckshot oro btebby metallic sulphides (1). In some places quartz veins 15-50m USH
In and stringers may be seen In this horizon. Away from the
E._ type section, a higher ratio of shale to arenites may be
0> seen; In some cases the USH Is almost entirely of shale .......
0>
> The lewermost lavas of Unit5 are amygdaloidal and grey In Cf):.;:: w
(I] colour (5). Individual flows are thin and Identifiable by their
amygdaloidal flow tops, Thicker flows exhibit a porphyritic 10.2-105m UNIT 5 ffi
~ affinity. The uppermost flows display Intense alteration and Cf)
.S contain vuggy quartz (4). Higher In succession, sediments LL
U compriSing quartzwackes (3) with shaly partings (2»{
o
..0..>.. become increasingly dominant over lavas. CONCOMMITANT z
.e . ---''';'''_--__;''---~----
'0> EXTRUSION
o
i=
In ] Altered grey lava series - generally non-amygdaloldal and OF UNITS 4 & 5,
~ "~VVVVVyy.,yy equigranular (6), displaying varying degrees of alteration. ~a. N:" 6 :::::::::: SPoradic clusters of amygdales. Thicker flows plagioclase n,"V YVVYvvv'O;vv
v v v v v v v v v v v v v v v porphyritic. Sedimentary Intercalations are very rare. 6-78m
Z
~ VVVVVWyvvvvvvvv
UNIT 4 ~ LL
YVVYVVVYVY"Y"''''' ~.
(I]
u 000000 We _,
(I). .°0°000I? ... <? .~ . ~.;'? The unit is characterised by large volumes of sporadically o
0> I
> amygdaloidal lava (8), the Individual flows of which are:;:; Woften difficult to discern. Some flow top do however display
..(.I..]. Cl:::--- a greater amygdaloldal affinity, which can facilitate thee o0> .......... recognition of. Individual flows from place to place. (JJ
In .--- Extremely dense clustering of amygdales was also noted,
0._> .:.:..:.:.: -::-:-:::f-n~'r--= . albeit on an irregular basis .a.
.Q_) :~~~~:~:.~I.n¥terlms of their appearance, the lavas are greenish-grey In000000 colour, largely due to the presence of chlorite as both an
00°000 amygdale filling and as a ground mass alteration phase.
9.8-348m UNIT 3
.~. o.. '?.~. P .. '? Although the lavas are generally equigranular, occasional
. porphyries (11) do exist.
Less prevalentfeatures of Unit 3 include restricted epidote
horizons (10), Which are greenish-yellow in colour and do
not appear to bear any relationship to stratigraphy.
Elsewhere, the lavas contain layered material (9) which
has been interpreted as being of tuffaceous origin. The
lewermost flows of the unit frequently contain quartz or
chalcedony vugs and vein networks (12).
E Featureless quartz-feldspar porphyries (13). Type localityo contains .pillow lavas (15), which grade upwards Into 4.9-110m UNIT 2
0> pyritiferous shales and subsequently quartzwackes (14). ..--
o(I]
In The unit comprises massive quartz-feldspar porphyries >
(16) which are coarser and more developed than those of z
(I)
o the OYef1ying Unit 2. Its phenocryst content Is largely 9.8-134m UNIT 1 w_,
t euhedral, associating with blebby chlorite. The type section o
0> contains a vein breccia (17) which has been interpreted as> Ibeing a pseudotachy1ite. W
Cl:::
The lower portion of this unit Is dominated by diamictite o(JJ
(19), of lava clasts in a carbonate matrix, which in the type
area grades upwards into sandy and shaly material (18): 5.9-16.1m LSH
In other sections only diamictites are present.
Figure 6.1 Composite stratigraphic type section for the Rietgat Formation
Chapter - 6 - Summary & Type Section - 175
6.7 Scope for future study.
• It is suggested that the geographical area of the current study is too small. A wider
area would have facilitated a more comprehensive geochemical, stratigraphic and
tectonic appraisal of the Rietgat Formation.
(1) A problem that faced the current study was the lack of suitable geochemical data.
The inclusion of isotopic and more detailed REE data would have assisted in the
formulation of a more accurate petrogenetic model for the Rietgat Formation,
particularly in the context of the Ventersdorp Supergroup or even the Kaapvaal
eraton as a whole.
ei' It has been noted that very little study of the Allanridge Formation has been
undertaken: such a study could surely contribute to our understanding of the
geology of the Ventersdorp Supergroup as a whole.
Chapter - 6 - Summary & Type Section - 176
ACKNOWLEDGEMENTS.
I wish to express my gratitude to Billiton SA for their financial support, without which
,"
this project would not have been possible, Anglovaal Ltd. are thanked for supplying
the borehole core examined during the course of this project and for providing field
accommodation in Allanridge.
Grateful appreciation goes to Prof Willem Van Der Westhuizen, firstly for instigating
and supervising this project and secondly for his forbearance while awaiting the
corrected version of this thesis. Or. Derik de Bruiyn is thanked for his eo-supervisory
role and his unrelenting patience when answering my many questions.
Drs. Kate Smith and Martin Van Zyl are sincerely thanked for undertaking my
statistical analyses. Their willingness to explain statistical concepts that would
otherwise have been beyond my comprehension is gratefully acknowledged.
Extended thanks goes to Peet Roodt, Jonas Choane and Daniel Radigkomo for their
assistance in sample preparation and to Lynette Wirthel and Andries Felix for their
impeccable drafting skills.
Finally, I wish to recognise the assistance of my current employers forallowing me the
necessary time to complete this study while stationed in West Africa: Ian Tomlinson, in
particular, is thanked for his assistance in this regard.
JEREMY CROZIER
Conakry, Republic of Guinea
12th February 2001
Acknowledgements - 177
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APPENDIX 1: ANALYTICAL PROCEDURES.
ALI Rare Earth Element Analysis .
. The analytical procedure used by the University of Cape Town to determine the REE
content of the sample material is summarised below:
Approximately 50 mg of sample powder was dissolved using standard, multi-stage
HFIHN03 digestion apparatus. The solution was then diluted to 1%0 of its original
concentration using a 2% HN03 solution containing 10 ppb of In and Re, which were
employed as internal standards. Only high-purity, bottle-distilled acids and Millipore
water were used.
The dissolved and diluted samples were subsequently analysed for REE using a Perkin
Elmer/Sciex Elan 6000 lep-MS. The ICP-MS instrument parameters used were as
follows:
Nebuliser gas flow = 0.94 I per min.
Main gas flow = 15 I per min.
Auxiliary gas flow = 0.75 I per min.
ICP RF forward power = 1100 W
Pressure in the quadrupale chamber = 2.03*10A-5 tOIT.
Nickel sampler and skimmer cones were used. The Elan 6000 was operated in its peak
hopping mode, using the auto lens option, dwell times of 50 ms per amu and total
Appendix 1 - 193
integration times of 3 sper analyte peak. Before analysis, the instrument was
optimised to minimise interferences by oxide species and doubly charged ions
(CeO/Ce < 3 %; Ba++/Ba+ < 3 %). In addition, the .data were corrected for Ba and
REE oxide interferences. Calibration was achieved by external standardisation with
one blank and two synthetic, multielement REE standards. In and Re were used as
internal standards to correct for any instrumental drift during. the analysis period.
Blank subtraction was carried out after internal standardisation for both standards and
samples.
All of the samples were analysed twice and the data set out in this study represent
.average values of those repeat analyses. The relative standard deviation (RSD) for
these repeat analyses was mostly better than 1 % and always better than 3 % for all
samples and elements. The same deviations apply to repeat analyses of both in-house
and international reference standards, (ALR-33G and 18-2 respectively). Based on
. repeat analyses of ALR-33G and 18-2reiative to tabulated values for these two ..
.materials, the accuracy was mostly better than 5 % and always better than 9 %.
...., '
A1.2 XRF Analytical Procedure,
All of the XRF speetrometry undertaken during the course of this project was
conducted at the University of the Orange Free State on a Philips PW-1404
spectrometer. American, Canadian, Japanese, Norwegian, South African and French
standards were used in the calibration of this apparatus, in conjunction with Philips
X40 analytical software.
Appendix 1 - 194
The 412 samples collected while core-logging were split in two, crushed and then
milled to -300 mesh. Approximately 109 of powder from each sample was then
pressed into a briquette, using boric acid as a base. These pellets were used in the
determination of both the trace element abundancies and the Na20 %. A further 3g of
sample powder was accurately weighed into a silica crucible and heated to 110°C for a
period of 12 hours, after which it was again weighed. The weight difference was used
in the calculation of the H20- presence in the sample. The powder was then ignited in
a kiln at 1000°C for 6 hours, following which it was re-weighed. This weight loss was
used to calculate the loss on ignition (known as the LOl) and represents the loss of
volatile contents, such as H20+ and C02. Following ignition, approximately O.3g of
the remaining sample was mixed with a fluxing agent, melted at 980°C and then
pressed into fusion beads. The beads were used in the determination (with the
exception of Na-O) of the major oxide composition of the samples.
Appendix l - 195
APPENDIX 2: ANALYTICAL DATA - X-RAY DIFFRACTION.
Appendix 2 - 196
a..i.
0 -ai - ai::ë ai Nt: .;;: ai ai ai .<;::DEPTH u 0 ë
SAMPLE UNIT .0S .-s ..: 0 '-';: '0 '-u::s u 0 -; C(metres) I
0 ~ 0' ::
I
;:s
I iiS 'ë. '';:; '-'l U u<
ai
- '"'"
DKL6-10 2 718.80 X X X X
DKL6-11 1 730.00 X X X X
DKL6-11A 2 734.19 X X X X
DKL6-11B 2 737.34 X X X X
DKL6-12 2 742.00 X X X X
DKL6-13 1 753.32 X X X X
DKL6-13A 1 759.98 X X X X
DKL6-13B 1 772.20 X X X X
OKL6-14 1 773.15 X X X X
J1)KL6-15A 3 782.96 X X X X
DKL6-16 3 790.15 X X X X
OKL6-16A Tuff 800.12 X X X
DKL6-17 Tuff 802.00 X X X
DKL6-8A 1 703.51 X X X X X
OKL8-10 2 779.50 X X X
OKL8-1l 1 798.75 X X X X X
DKL8 -12 2 806.00 X X X X X
DKL8 -13 3 831.29 X X X X X
DKL8-8 2 755.60 X X X
DKL8-9 2 774.80 X X X
DKPI-I Intrusive 827.51 X X X X
OKPI-I0 5 1,063.09 X X X X
OKPl-ll 5 1,079.32 X X X X
.DKPI-12 5 1,122.68 X X X X
DKPI-2 Intrusive 868.21 X X X X
OKPl-3 Intrusive 907.00 X X X X X
DKPl-4 I Intrusive 925.00 X X X X X'«'<' IOKVl-5 Intrusive 978.89 X X X X X I
DKPI-6 Intrusive 980.72 X X X X X
DKPl-7 1 995.36 X X X X. X
OKPl-8 3 1,023.36 X X X X X
DKPl-9 4 1,049.16 X X X X X
ER02-1 Intrusive 240.50 X X X X X
ER02-2 Intrusive 322.05 X X X X
ER04-0 1 637.00 X X X
ER04-1 1 640.00 X X X
ER04-10 1 726.70 X X X
ER04-11 3 732.40 X X X
ER04-2 1 642.06 X X X X
ER04-3 1 645.19 X X X X
ER04-4 1 648.29 X X X X
ER04-5 1 650.40 X X X X
ER04-6 I 651.10 X X X X
ER04-7 1 654.00 X X X X
ER04-8 1 689.00 X X X X
ER04-9 1 724.01 X X X X
KFN2-1 1 682.95 X X X X
KFN2-10 1 791.50 X X X X
KFN2-11 1 808.27 X X X
KFN2-12 3 828.75 X X X X
KFN2-13 3 842.00 X X X X
KFN2-14 3 861.77 X X X X
Appendix 2 - 197
~...
::0a - ~ ~~ !'ol .;;:: ~ ~ .-::DEPTH Cj -:.c t: 0 .--::UNIT 0 "- ~0SAMPLE <li 0 -·u -0.s -::s Cj(metres) :;;: 0' .ë. ; .::0 Ol ::"s i:i5~ Io;l U Cj~ <-
1.1.
KFN2-16 3 885.09 X X X X
KFN2-17 3 903.11 X X X ../'X
KFN2-IS 3 921.32 X X X X
KFN2-19 3 935.96 X X X X
KFN2-2 2 692.86 X X X X
KFN2-20 3 946.22 X X X
KFN2-21 3 958.97 X X X /
KFN2-22 5 994.26 X X X X
KFN2-24 5 1,015.82 X X X X
KFN2-2S 5 1,027.68 X X X X
KFN2-26 5 1,037.91 X X X X
KFN2-3 2 712.97 X X X X
KFN2-4 I 728.87 X X X X
KFN2-S 2 739.60 X X X
KFN2-6 2 748.20 X X X
KFN2-7 2 758.62 X X X
KFN2-S 2 774.51 X X X
KFN2-9 1 781.21 X X X
MAI-I Tuff 853.20 X X X
MAl-lO 3 971.65 X X X
MAl-tl 3 972.92 X X X
MAI-12 3 987.00 X X X X
MAI-13 3 1,005.50 X X X X
MAI-14 3 1,029.70 X X X X
MAl-IS 3 1,053.17 X X X X
MAI-16 3 1,100.00 X X X X
MAI-17 I Intrusive 1,125.14 XMAI-LS 5 1,142.18 X I
X !f
v
A X X
MAI-19 5 1,162.98 X X X X
MAI-2 I 858.30 X X X X
MAI-20 5 1,177.00 X X X X
MAI-21 5 1,210.00 X X X X
MAI-3 I 870.98 X X X X X
MAI-4 I 882.78 X X X X X
MAI-S I 893.18 X X X X X
MAI-6 2 905.00 X X X X X
MAI-7 I 935.11 X X X X
MAI-S 2 946.12 X X X X
MAI-9 3 965.32 X X X X
MA2-1 1 919.51 X X X X
MA2-IO 3 1,085.87 X X X X
MA2-1I 3 1,097.22 X X X X
MA2-l2 3 1,122.85 X X X X
MA2-13 3 1,137.19 X X X X
MA2-14 3 1,156.85 X X X X
MA2-IS '3 1,165.12 X X X X
MA2-L6 Tuff 1,177.50 X X X
MA2-17 4 1,187.65 X X X X
MA2-IS 5 1,~04.21 X X X X
MA2-2 1 938.77 X X X X
MA2-3 1 948.21 X X X X
MA2-4 2 954.47 X X X X
Appendix 2 - 198
~
J,..,
:0:a ~ ~~ N .-;;:: ~ -~ ~ ."':::DEPTH C,J 1:: '::::; 0 "0
SAMPLE UNIT 0.05 :-Ei .., C,J -0 '"e0 '-u(metres) < ::s .50 o '::" -;s ii5~ ~ . U -C,J~ <
""
MA2-S I 962.65 X X X X
MA2-6 I 988.39 X 'X X X
MA2-7 3 1,015.92 X X X X
MA2-8 I 1,044.47 X X X X
MA2-9 3 1,067.35 X X X X
MALI-I I 702.35 X X X X
MALI-lO 5 860.75 X X- X X X
MALI-II 5 895.36 X X X X X
MALI-2 I 706.85 X X X X
MALl-3 I 7:3.65 X X X X
.1
MALI-4 2 ï21.20 X X X X
MALI-S 1 731.26 X X X X
MALl-6 1 760.42 X X X X
MALI-8 5 818.96 X X X X
MALI-9 5 834.75 X X X X X
MAL4-1 2 759.61 X X X X X
MAL4-2 1 778.80 X X X X X
MAL4-3 I 809.12 X X X
MAL4-4 1 830.37 X X X X
MAL4-S 3 840.71 X X X X
MAL4-6 3 858.21 X X X X
MAL4-7 3 869.42 X X X
MAL4-8 3 889.91 X X X X
NVTl-IO, , 2 1,347.31 X X X XI
NVTr-lf. 2 : 1,354.95 X X X X
NVTl-12' 2 1,367.13 X X X X
fNVTl-13 I 2 1,379.49 I X I X X
,~,..\.~~Il~;
N,,"fl-14 I ....L. 1,387.18 X v.I~ X ,-
NVTl-lS I 1,397.89 X X X
NVTl-16 1 1,411.07 X X X
NVTl-17 3 1,420.27 X X X
NVTl-18 3 1,430.37 X X X
NVTt-19 3 1,440.06 X X X
NVTt-2 2 1,313.00 X X X X
NVTl-20 3 1,442.10 X X X
NVTl-20A 3 1,454.17 X X X X
NVTt-21 3 1,472.82 X X X X
NVTt-22 3 1,485.83 X X X
NVTt-22A 3 1,499.63 X X X X
NVTt-23 3 1,518.75 X X X X
NVTt-24 3 1,533.50 X X X X
NVTI-2S 3 1,548.20 X X X X
NVTt-26 3 1,556.61 X X X X
NVTl-27 3 1,567.19 X X X X
NVTt-28 3 1,579.46 X X X X
NVTl-29 '3 1,590.89 X X X X
NVTI-30 3 1,599.23 X X X X
NVTl-32 3 1,625.27 X X X X
NVTt-33 3 1.,638.55 X X X X
NVTt-34 3 1,657.24 X X X X
NVTl-3S 3 1,665.50 X X X X
NVTl-36 3 1,677.24 X X X X
Appendix 2 - 199
~
:0"a'" ~.~.. N ..;.;:. ~ .~.. ~DEPTH CJ 1:: ... O..u. .
~~
0 :ë 0 0';::
0 '0
8AMPLE UNIT C oe(metres) .5 < ::
Osl CJ 0<Il 'a -; c: '';::0 Cl :::s; as ~ U CJ~ <
'""" - ._._ ...
NVTl-37 3 1,714.10 X X X X
NVTI-38/'" 3 1,726.17 X X X X
NVTl-39 3 1,132.13 X X X X
NVTI-4 .» 2 1,316.86 X X X X
NVTI-40 3 1,750.26 X X X X
NVTt-44 4 1,800.67 X X X X
NVTl-46 z 4 1,818.27 X X X X
NVTl-47 4 1,847.12 X X X X
NVTI-48 4 1,859.75 X X X X
NVTl-49 4 1,874.10 X X X X
NVTt-5 2 1,318.62 X X I ,v~ X
NVTl-5l 5 1,890.87 X X X X
NVTt-52 5 1,910.00 X X X X
NVTt-53 5 1,940.82 X X X X
NVTl-6 2 1,322.89 X X X X
NVTl-7 2 1,326.68 X X X X
NVTI-8 , 2 1,337.00 X X X X
NVTl-9 2 1,341.09 X X X X
PDEl-l 1 749.95 X X X X X
PDEI-2 1 765.29 X X X X X
PDEl-3 1 778.20 X X X X X
PDEI-4 1 799.10 X X X X X
PDEl-5 1 818.68 X X X X X
PDEl-6 Sediment 848.21 X X
PDEl-7 Sediment 849.69 X X
84-1 1 736.18 X X X X
184-10 I 809.00 X X X X X
..o:,,\~. I
84-11 1 1 811.76 X X X X X.
84-12 1 821.07 X X X X X
84-13 I 831.11 X X X X X
84-14 1 843.87 X X X X. X.
84-15 1 855.70 X X X X X
84-16 I 867.10 X X X X X
84-17 3 838.20 X X X X X
84-2 I 744.17 X X X X
84-3 2 750.72 X X X X
84-4 I 755.13 X X X X
84-8 2 794.28 X X X
84-9 1 800.85 X X X X X
86-1 2 738.25 X X X X
86-1B I 742.00 X X X X
86-2 I 747.10 X X X X
86-3 I 800.70 X X X X
86-3A 1 833.89 .X X X X
86-38 I 759.62 X X X
86-3C 'I 773.61 X X X
86-3D 1 790.15 X X X
86-3E 1 823.00 X X X X
86-3F 1 836.65 X X X X
86-5 I 841.75 X X X X
86-6 1 854.00 X X X X
TKl/IB (outcrop) outcrop X X X X
Appendix 2 - 200
C..I.I.
0 CI.I CI.I::a CI.I N .;; CI.I CI.I CI.I .':::
DEPTH CJ t: -0 ·Z -0 ·-u ë
SAMPLE UNIT
0 :-.0 ..: -CJ "0.5 :;;: ::I '" =0 .ë. -; C(metres) 0 o ·Z::I~ r..< U CJ~
..C.I..I
._. _. . .
TK1I3 (outcrop) outcrop X X X X
TK2/2F (outcrop) outcrop X X X
TK2/21 (outcrop) outcrop X X X X
TNT2-1 1 725.87 X X X
TNT2-1O 3 946.05 X X X
TNT2-13 3 986.06 X X X X
TNT2-14 5 1,021.62 X X X X
TNT2-15 5 1,036.28 X X X X
TNT2-16 5 1,055.69 X X X
TNT2-3 1 747.65 X X X ..
TNT2-4 1 762.49 X X X I
TNT2-5 I 778.86 X X X
TNT2-6 3 835.84 X X X X
TNT2-7 3 897.65 X X X X
TNT2-9 3 933.97 X X X X
Appendix 2 - 201
APPENDIX 3: ANALYTICAL DATA - X-RAY FLUORESCENCE
Appendix 3 - 202
DKL6-10. DKL6-11 DKL6-11A DKL6-IIB DKL6-12 DKL6-13. DKL6:13A DKL6-13B DKL6-14 DKL6-15A DKL6-16 DKL6-16A DKL6-17 DKL6-6 DKL6-8A
Depth (metres) 718.80 730.00 734.19 737.34 742.00 753.32 759.98 772.20 773.15 782.96 790.15 800.12 802.00 444.15 703.51
Forrnaftun Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat
Unit 4 5 4 4 4 5 5 5 5 3 3 Tuff Tuff Tuff 5
wt.%
sio, 58.44 59.09 50.84 56.32 55.04 55.14 56.89 56.10 58.16 47.66 49.66 84.66 64.82 53.71 55.20
TIOl .. 1.57 1.51 1.56 1.58 1.62 1.44 1.60 1.26 1.58 1.67 1.50 0.36 2.24 1.20 1.49
A1l0J 14.81 14.50 15.06 15.11 15.71 14.71 15.26 12.17 15.14 15.16 14.92 5.69 12.99 13.36 14.55
FelOJ 11.00 8.00 6.13 10.95 13.79 7.89 10.11 9.95 8.41 14.22 10.96 6.55 10.13 11.15 9.31
MnO 0.11 0.10 0.20 0.13 0.14 0.11 0.09 0.15 0.08 0.14 0.10 0.06 0.07 0.14 0.11
MgO 4.86 2.73 2.18 3.81 5.31 2.80 4.17 4.22 3.63 8.71 6.44 1.57 2.73 3.90 4.08
CaO 2.30 4.96 1O.D2 4.49 2.62 839 4.85 7.70 4.89 3.88 6.44 1.09 2.49 7.51 6.13
NalO 2.06 2.84 0.04 2.79 1.56 2.73 3.08 1.88 3.~6 1.61 2.79 0.09 0.01 1.53 0.78
KlO 0.96 1.16 4.20 0.49 0.81 151 0.55 0.22 0.30 0.45 0.03 0.97 3.18 1.59. 2.32
PlO, 0.75 0.70 0.80 0.76 0.77 072 0.76 0.63 0.76 0.87 0.79 0.08 0.36 0.27 0.72
H1O- . 0.11 0.04 0.09 0.05 0.07 005 0.08 0.10 0.09 0.10 0.07 0.06 0.10 0.05 0.07
LOl 3.42 4.49 8.89 4.28 4.01 5.85 4.20 6.58 3.56 5.43 6.50 1.66 2.86 5.68 6.63
TOT 100.39 100.12 100.01 100.76 101.45 101.34 101.64 100.96 100.46 99.90 100.20 102.84 101.98 100.09 101.39
ppm
Rb 31.80 40.20 154.00 17.10 32.40 4250 12.00 1.40 4.40 7.30 0.01 32.00 164.60 21.70 78.90
Ba 345.80 428.30 1,354.20 227.io 351.50 81680 333.00 249.90 291.90 643.30 55.10 529.70 850.80 450.40 589.50
Sr 128.10 253. 70 66.60 271.00 176.80 549.20 492.80 406.60 706.60 247.30 227.10 43.30 62.10 533.90 85.30
Zr 349.90 329.20 366.80 346.00 350.30 315.10 333.00 275.70 333.60 239.20 219.70 92.80 253.60 179.30 337.50
Nb 15.00 14.40 18.00 16.40 16.60 15.50 15.60 13.20 15.20 13.00 11.70 . 3.20 13.60 10.30 15.90
Ni 82.40 55.60 52.20 76.40 82.90 73.00 72.70 69.10 77.00 124.40 118.10 52.90 160.60 149.40 77.10
Zo 104.40 80.80 114.60 123.30 142.50 93.40 . 93.80 102.80 111.20 141.50 95.70 44.20 75.10 104.70 83.20
Cr 218.40 215.40 186.80 229.70 246.50 21250 238.30 173.10 228.80 379.90 324.70 190.00 139.90 53.20 207.60
Cu 32.80 13.30 16.20 17.80 19.20 25.40 18.20 11.50 17.90 106.10 10.30 28.60 170.50 116.20 7.30
V 242.80 21,3.50 201.70 194.50 272.90 197.50 241.20 197.30 214.00 274.60 249.70 70.60 300.90 173.90 228.20
Y 38.20 37.00 51.20 45.50 43.60 38.70 39.40 29.40 38.20 36.10 33.20 8.60 46.00 21.60 37.00
Sc 20.40 17.50 21.20 12.10 26.80 1800 19.70 15.30 21.40 20.40 19.20 6.70 22.10 15.80 24.10
Co 45.30 34.70 17.20 41.30 48.00 38.00 45.80 45.90 40.40 72.00 54.10 27.30 104.30 64.40 35.50
CIPW Norms. (%)
Quartz 33.71 26.47 16.93 25.91 32.32 16.65 22.89 26.95 21.36 18.68 12.92 75.07 44.51 20.99 25.87
Corundum 8.21 1.22 3.73 9.69 - 2.59 - 1.34 7.40 0.48 2.63 5.85 - 1.35
Zircon 0.07 0.07 0.07 0.07 0.07 0.06 0.07 0.06 0.07 0.05 0.04 0.02 0.05 0.04 0.07
Ortboelase 5.87 7.19 27.33 3.01 4.99 9.37 3.34 1.38 1.83 2.82 0.19 5.68 19.04 9.97 14.51
A1bite 18.00 25.14 0.37 24.48 13.17 24.20 26.77 16.87 33.73 14.43 25.21 0.75 0.08 13.72 6.97
Anortbite 6.85 21.16 31.35 18.11 8.08 24.59 19.88 25.61 20.26 14.62 28.71 4.99 10.34 26.42 27.34;>
-:::l Diopside - 9.94 - - 7.55 - 5.24 - - - - 6.03 -
"0
(I> Wollastonite - - - - - - - - - - \ - -~ Hypersthene 12.50 7.11 1.36 9.84 14.05 3.81 10.67 8.72 9.34 22.99 17.13 3.87 ~~.'87 7.50 10.73
0-
Chromite 0.05 0.05 0.04 ·0.05 0.05 0.05 . 0.05 0.04. 0.05 0.08 0.07 0.04 0.03 0.01 0.04X
w Haematite 11.36 8.37 6.73 11.35 14.05 8.27 10.38 10.55 8.69 15.07 11.71 6.48 " 10.23 11.82 9.83
Ilmenite 0.24 0.22 0.46 0.28 0.32 . 0.24 0.19 0.34 0.17 0.31 0.23 0.12 0.20 0.36 0.25
oN Spbene - - 3.62 0.28 - 3.40 - 2.84 - - - - 2.66w Apatite 1.85 1.74 2.09 1.87 1.92 1.80 1.86 1.59 1.87 2.20 2.00 0.19 0.87 0.68 1.81
Rutile 1.49 1.47 - 1.49 1.48 _-. 1.54 - 1.54 1.61 1.48 0.29 2.16 - 1.44
.é
-
DKL8-IO DKL8-11 DKL8-12 DKL8-13 DKL8-8 DKL8-:I. DKPI-IO DKPI-II DKPI-12 DKPI-2 DKPI-3 DKPI-4 DKPI-5 DKPI-7 DKPI-8
..
Deptb (metres) 779.50 798.75 806.00 831.29 755.60 774.80 1,063.09 1,079.32 1,122.68 868.21 907.00 925.00 978.89 995.36 1,023.36
Formation Rietgat Rietglit Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat
.Unlt 4 5 4 4 4 4 1 1 I Intrusive Intrusive Intrusive Intrusive 5 3
wt.%
SIOI 53.91 55.83 47.33 48.06 57.77 56.64 56.6.1 59.25 56.36 48.60 47.23 50.00 48.59 56.35 53.63
'1'101 . I.4U '1.45 1.7U U3 1.28 1.56 1.29 1.42 1.33 1.66 1.72 1.79 1.77 1.61 1.50
AllO) 13.74 14.00 15.42 13.98 13.44 14.31 13.36 15.40 14.08 13.90 14"12 13.83 14.51 15.27 14.49
FeIO) 9.81 9.45 12.81 10.40 10.97 11.00 11.47 7.46 9.69 16.06 16.30 15.70 16.28 7.92 10.62
MnO 0.12 0.14 0.16 0.13 0.12 0.11 0.15 0.09 0.11 0.21 0.27 0.27 0.27 0.17 0.19
MgO 3.04 4.09 4.23 4.74 3.19 4.40 4.61 2.30 3.08 5.66 5.75 6.44 5.91 3.82 6.93
CaO 6.96 5.53 6.38 8.12 4.23 3.40 4.23 4.08 5.92 9.80 8.22 6.08 7.19 5.70 5.23
NOlO 1.36 3.02 2.14 2.39 0.06 0.20 1.97 2.84 2.70 2.34 2.60 2.56 2.70 5.45 3.06
KlO 1.70 0.23 0.72 0.38 2.21 2.09 0.30 2.75 1.06 0.11 0.57 0.62 0.96 0.03 0.08
PIOS 0.65 0.67 0.76 0.81 0.57 0.71 0.53 0.62 0.57 0.22 0.23 0.24 0.25 0.82 0.77
HIO- 0.06 0.06 0.11 0.09 0.08 0.14 0.08 0.10 0.05 0.14 0.10 0.08 0.06 0.08 0.09
LOl 6.69 4.47 6.34 7.43 5.49 4.97 4.67 3.39 5.07 2.11 2.97 2.93 2.27 2.10. 2.93
TOT 99.44 98.94 98.10 98.06 99.41 99.53 99.27 99.70 100.Q2 100.81 100.08 100.54 100.76 99.32 99.52
ppm
Rb 68.20 9.90 29.50 17.10 87.50 75.70 4.60 65.70 21.90 4.20 11.70 11.50 2i.80 0.01 0.01
.Ba 465.30 231.50 558.90 180.50 673.80 898.50 182.20 1,689.90 584.60 262.90 556.90 500.10 1,370.00 30.50 116.00
Sr 330.30 922)0 266.70 404.80 71.80 56.10 352.10 480.70 600.10 693.50 346 -9, 0 240.50 " 409.20 220.90 517.70
Zr 319.50 306.30 369.50 228.70 313.30 351.50 318.90 353.20 342.80 169.40 187.90 190.90 185.60 326.10 226.00
Nb 16.30 15.80 19.20 12.70 13.60 16.80 15.20 16.00 16.20 13.00 13.80 12.20 13.80 15.20 12.90
Ni 18.30 18.90 24.50 27.60 20.90 23.60 91.00 73.30 78.50 127.10 104.70 85.00 109.20 63.70 109.10
Zo 72.10 78.30 93.70 112.90 46.20 73.60 Hi8.70. 68.60 122.70 121.50 136.10 121.20 138.30 49.00 108.30
Cr 106.30 115.60 127.90 110.30 128.80 111.60 341.40 382.30 352.10 125.90 157.80 150.90 154.20 192.40 291.90
Cti 24.60 16.50 13.00 7.00 25.20 690 12.40 35.90 23.80. 186.70 161.50 152.80 176.70 7.00 30.80
V 44.20 43.30 52.80 39.60 35.90 41.70 215.40 193.50 197.20 250.80 311.20 338.70 323.80 206.30 237.50
Y 181.80 210.00 223.50 311.90 126.10 224.90 37.30 35.60 40.70 36.50 38.30 36.70 38.20 41.00 36.40
Sc 192.70 207.20 290.40 244.10 198.80 241.00 21.40 18.20 18.90 23.10 26.10 28.50 35. io 18.20 20.90
Co 31.00 35.30 48.30 37.30 33.70 36.60 57.30 37.00 45.30 76.40 79.00 74.90 82.30 33.80 55.00
CIPW Norms. (%)
Quartz 24.52 22.59 15.60 13.70 39.16 3774 31.19 22.39 22.52 10.16 7.60 11.93 7.75 10.46 16.65
Corundum - 0.35 1.46 4.93 7.66 3.52 1.70 - - - - - 1.70
Zircon - - - 0.06 0.07 0.07 0.03 0.04 0.04 0.04 0.07 0.05
Orthoclese 10.84 1..44 4.64 2.48 13.92 13.08 1.88 16.92 6.61 0.66 3.48 3.76 5.77 0.18 0.49
Alblte 12.41 27.06 19.76 22.33 0.54 1.79 17.63 24.98 24.07 20.09 22.68 22.21 23.21 47.47 26.83
>- Anorthite 28.45 24.42 29.12 29.05 18-4, 0 12.95 18.71 . 17.45 24.47 27.53 25.99 25.07 25.11 17.64 21.89
-0 Diopside - 3.33 - - - - - 12.23 7.58 - 3.77 0.75
-0
(1) Wollastonite - - - - - - - - - - - - -
::s Hyperstbene 8.17 10.79 11.49 11.49 8.47' 11.61 . 12.15 5.95 8.08 8.64 . 11.25 16.44 13.21 9.45 17.880-
X Cbromite - - - 0.07 0.08 0.08 0.03 0.03 0.03 0.03 0.04 0.06
w Haematite 10.58 10.01 13.98 11.49 11.69 11.65 12.14 7.75 10:21 16.30 16.80 16.10 16.54 8.15 11.01
Ilmenlte 0.28 0.32 0.37 0.31 0.27 0.25 0.33 0.17 0.23 0.49 0.62 0.61 0.61 . 0.37 0.42
tov Spbene 2.98 - - 3.75 - - - 2.06 3.51 3.56 3.15 3.64 3.59~ Apatite 1.66 1.68 1.96 2.12 1.44 1.78 LJ3 1.55 1.43 0.53 0.56 0.59 0.61 2.00 1.90
Ruti1e 0.15 LJ7 1.66 I l.i2 1.52 1.19 1.38 0.44 - - 0.23 - - 1.33
'r..
\
DKPI-9 ER02-f ER02-2 ER04-1I ER04-2 ER04-:I ER04-4 ER04-5 ER04-6 ER04-7 ER04-8 ER04-9 .I KFN2-1 KFN2-10 KFN2-1I
Depth (metres) 1,049.16 240.50 322:05 732.40 642.06 645.19 648.29 650.40 651.10 654.00 689.00 724.01 682.95 791.50 808.27
Formation Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat. Rietgat Rietgat Rietgat Rietgat Rietgat
Unit 2 Intrusive Intrusive 3 5 5 5 5 5 5 5 5 5 5 5
wt.%
SiOI 57.78 50.75 53.23 50.43 50.52 55.69 48.53 59.28 47.85 53.04 57.81 53.90 54.12 56.80 48.18
:1'101 . 1.64 2.04 1.15 1.53 1.53 1.33 1.37 1.32 1.46 1.44 1.55 1.46 1.37 1.46 1.81
AllO, 16.21 14.07 13.36 13.69 14.97 12.81 14.51 11.40 14.99 13.95 15.38 13.96 15.17 14.48 16.79
FelO, 9.48 15,99 11.55 12.38 11.02 8.51 11.12 10.45 9.38 7.81 9.67 10.05 9.80 9.77 13.70
MoO 0.12 0.19 0.24 0_14 0.10 0.11 0.11 0.10 0.11 0.10 0.10 0.11 0.1 I 0.1 I 0.12
MgO 3.68 3.80 7.91 5.45 6.10 4.61 5.93 5.89 5.58 3.88 3.83 3.97 5.17 3.91 6.26
CoO 2.49 8.04 5.05 6.86 6.12 7.54 7.83 3.90 8.84 6.75 3.62 5.98 5.44 6.37 3.97
NOlO 2.00 2.14 3;]3 2.82 0.45 0.43 1.51 1.45 1.82 1.80 2.84 2.88 1.29 2.86 1.91
KlO 4.40 1.37 O.IS 0.27 2.08 1.97 0.80 0.43 1.11 1.72 1.42 1.58 1.64 1.03 2.40
PIOS 0.72; ,. " .: 0.30 0.46 0.80 0.74 0.71 0.68 0.63 0.73 0.69 0.75 0.71 0.68 0.70 0.91
HIO- 0.08 0.34 0.25 0.13 0.14 0.09 0.09 0.07 0.11 0.06 0.07 0.07 0.12 0.04 0.06
LOl 2.52 2.09 2.75 3.16 7.26 7.70 8.15 4.80 8.63 6.75 3.25 3.38 6.26 2.97 4.21
TOT 101.12 101.13 99.23 97.66 101.03 101.50 100.63 100.72 100.61 97.99 100.29 98.05 101.17 100.50 100.32
ppm
Rb 99.70 43.70 0.30 6.30 78.40 75.80 29.70 15.30 42.00 75.20 33.50 40.60 65.40 222.90 57.70
Ba 3,404.40 481.60 59.60 336.90 657.40 629.80 242.20 191.50 295.90 799.30 1,460.40 718.40 605.80 957.60 3,670.70
Sr 221.00 685.40 182.20 420.20 73.10 76.00 136.40 111.20 174.10 189.00 421.70 613.60 130.60 602.40 328.30
Zr 425.40 232.30 235.80 249.70 346.70 305.40 316.70 293.80 328.50 331.50 337.60 324.80 325.30 320.30 348.50
Nb 19.20 15.90 12.80 14.50 17.10 15.10 15.80 13.30 16.30 15.80 16.30 16.80 14.50 15.90 18.70
NI 108.60 60.20 151.00 95.60 78.50 52.20 86.40 62.00 76.50 68.90 80.30 72.20 51:00 74.90 91.20
Zo 60.70 124.70 109.80 129.80 104.40 69.30 92.20 104.60 97.80 87.20 115.70 103.40 67.10 89.10 150.80
Cr 429.20 54.80 534.20 267.70 224.00 176.50 211.60 202.20 229.00 195.60 227.10 210.10 133.30 212.60 218.30
Cu 18.90 201.50 22.40 24.50 32.00 11.80 12.80 27.10 6.70 20.70 11.50 19.90 12.90 ; 17.80 28.30
V 274.00 272.50 218.06 233.90 241.70 197.50 218.60 217.60 218.90 218.70 249.40 215.30 234.20 ; 201.40 257.60
Y 42.50 45.60 35.20 38.10 43.70 39.20 36.30 35.10 40.60 37.60 37.00 41.30 46.20 39.30 49.20
Sc 26.10 25.30 24.30 20.90 21.60 22.40 23.10 17.50 22.40 21.60 16.70 17.20 20.40 18.90 22.10
Co 52.90 63.00 61.70 54.70 51.40 34.80 44.50 55.30 41.50 35.40 50.10 44.00 43.60 48.90 56.70
CIPW Norms. (%)
Quartz 20.23 13.95 13.64 14.23 21.06 27.49 14.93 35.25 10.72 14.85 25.06 16.13 24.05 19.80 12.73
Corundum 6.10 - - - 2.74 - 4.11 - 23.76 4.36 - 3.11 - 5.94
Zircon 0.09 0.05 0.05 0.05 0.07 0.06 0.06 0.06 0.07 0.07 0.07 0.07 0.07 0.06 0.07
Ortheelase 26.17 8.22 0.92 1.69 13.16 12.45 5.13 2.'66 7.16 8.37 8.67 9.89 10.25 6.33 14.79
A1bite 17.01 18.34 27.52 25.28 4.07 3.88 13.83 12.80 16.76 12.14 24.78 25.75 11.52 24.82 16.83
Anortbite 8.61 25.11 22.84 25.36 27.46 29.06 32.98 15.98 32.08 23.75 13.99 21.73 23.99 . 24.28 15.36;l>
'0 Diopside - 5.68 - 0.27 - 1.25 . - - 4.34 - - 0.16 - -
'0
Cl> Wollastonite - - - - - - - - - - - -
:l
c.. Hypersthene 9.21· 6.96 20.47 14.26 16.26 11.67 15.98 15.30 13.13 8.26 9.84 10.38 13.58 9.99 16.23
x' Cbromite 0.09 0.01 0.11 0.06 0.05 0.04 0.05 0.04 0.05 0.04 0.05 0.05 0.03 0.05 0.05
w Haemante 9.53 16.20 12.00 13.12 11.77 908 12.04 10.90 10.21 6.36 9.97 10.62 10.34 10.02 14.26
Ilmenite 0.24 0.43 0.52 0.32 0.23 0.25 0.26 0.22 0.25 0.t'7 0.22 0.25 0.25 0.24 0.27
oIV Spbene - .4.52 0.11 3.58 - 317 3.08 - 3.57 - 3.48 - 2.77
<Jl Apatite 1.80 0.72 1.13 2.02 1.88 180 1.75 1.56 1.89 1.37 1.86 1.79 1.71 1.71 2.32
Rutile 1.52 - 0.88 - 1.51 ,~,! 0.09 1.26 - - 1.48 - 1.31 0.25 1.74
MAl-I MAI-2 MAI-J II1AI-4 MAI-S MAI-6 MAI-7 MAI-8 II1AI-9 MAl-lO i\'IAI·11 II1AI-J2 I\1AI-IJ MAI-14 MAl-IS
Depth (mctrcs) 853.20 858.30 870.98 882,78 893.18 905,00 935, II 946.12 965 ..32 971.65 972.92 9S7.00 1.005.50 1.029,70 1.053.17
Formalion Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Riclgi.lt Rietgat Rictgat Rietgat Rictgat Rietgat
Unit (New) Sediment I I I I 2 I 2 3 3 ?3 3 3 3 3
w(.%
SiO, 76.51 58.15 57.67 53,07 56.79 53,37 56,46 54,99 54,68 44.01 55,85 51.00 51.14 49,87 52,661
TiO, 1.07 1.44 1.31 1.37 1.43 1.42 1.50 1.72 1.71 1.74 1.34 1.49 1.52 1.51 1.44
AI,O, 5.53 14,00 14.31 14.34 15.01 14,S5 14,96 15,83 14.75 15,91 13.71 13.32 13.99 14.07 13,S3 ,
Fe,O, 10,20 14,37 9,19 10,24 10.91 11.67 10.62 11.35 9.79 11.10 S,60 10,51 11.29 11.51 9,6S
MnO 0.12 0.13 0.12 0.13 0,12 0.14 0,11 0.10 0,09 0,12 0.06 0,12 0,13 0,13 0.12
Ml!O 1.85 3.08 2.97 4,19 3.93 4, IS 3,63 4,49 4,76 5,R6 0,37 4.S2 5.60 5,67
4,92
CaO 3, II 2,50 6,63 7,17 4.20 5,S7 4.67 3,65 5.96 7,23 15,30 7,36 6.64 7,03 X,30
N:J,O 0,01 0,03 2,34 1.06 0,89 2.43 3,30 3,39 3.12 3.45 0,01 2,95 3,2S 3,12 2,93
K,O 0.02 1.84 0.69 1.66 2.14 0,72 0,)3 0,06 0,04 0.02 0,05 0.04 0,04 0,18 0,81
1',0. 0,14 0,65 0,62 0,67 0,67 0.67 0,70 0,R7 0.S9 0.91 0,77 0,79 0,82 O,SI 0,78
11,0- 0,01 0,02 0.02 0,05 0,07 0.04 0,05 0,05 0,06 0,04 0,01 0,10 0,07 0,07 0.03
LOl 3,56 5.17 5,17 7.39 5.21 5,83 4.42 3.57 4,69 6.76 1.64 4.83 2,52 2.45 2.14
TOT 102,13 101.38 101.04 101.34 101.37 101.19 100.75 100,07 100.54 '97,15 97,71 97,33 97.04 96.42 97,64
pprn
Rb 0,01 58.40 21.10 59,50 79.00 26,70 6,80 0.01 0.01 0,01 9,30 0,01 0,01 2.00 17.60
na 14.90 604.00 193.20 643.,70 877.60 323,70 153.40 60.50 65,40 46,60 89.20 59,20 87,30 351.50 1.306.90
Sr 35.70 41.10 414.00 88.20 73.40 151.00 303.40 264,80 579,10 274.10 5,482.60 433,50 490,80 526,90 468,80
Zr 133,20 324.00 296,70 318,70 318.70 317.10 321.30 346,50 268,30 261.60 86,80 225.20 228,90 221.50 225.70
Nb 13.00 15.80 13.30 15.70 14,10 15,00 14,20 16.90 14.50 13,30 15.00 12,20 13,20 12.70 13,10
Ni 320,70 53.10 50.50 60.70 65,90 56.10 72.40 82.20 103,50 120,90 28.80 99,60 114.20 118.20 100.70
Zo 64.70 83.30 . 97.80 87,90 85.70 96.60 129.20 97.50 92.00 97.70 9,90 109.50 92.80 81.60 78.00
Cr 1,098.60 148.90 130.20 147.50 153,20 161.90 206,80 207,60 275.40 321.70 209,50 286,50 31S,00 299.10 251.50
Cu 129,60 12,10 24,20 10.30 6,20 5.80 7,10 5.40 6,00 10,40 30.00 49,50 21.80 16,60 24,30
V 130.80 230.50 207.10 226,80 249,90 229,50 234.70 253,90 255.70 227.90 190,20 235.60 229,50 227.40 207,60
Y 12.50 32,60 35.80 39.00 33.00 36.10 38,90 44,20 42.50 37,10 44,00 38,00 37,10 36.30 35,20
Sc 19.70 21.60 16.50 18,90 18,90 21.60 18,50 18,90 20.40 20,90 26.60 22.40 21.60 21.90 19.40
Co 103.00 64,60 37.80 45.70 53.90 56,20 47,70 53.70 4S.40 59,50 17.40 52,30 55,]0 57,10 50,40
CII'W Norm s. ("lo)
Quartz 68.32 44.42 26.06 22.51 31.57 20,45 23.35 23.77 19,76 2,45 32.62 16.02 13,25 11.69 13.09
Corundum 0,17 9,27 - - 5,33 1.01 2,40 5,81 0,84 - - -
Zircon 0.03 0.07 0.06 0,06 0.06 0,06 0.06 0.07 0,05 0,05 0,02 0.05 0,05 0,04 0,05
Ortheelase 0.12 11.33 4,26 10.47 13.19 4.47 2.03 0.37 0,25 0,13 0,31 0,20 0,25 1.14 5,02
Albite 0,08 0.26 20.65 9,55 7.83 21.57 29.00 29,74 27,56 32,52 0.08 27.14 29.38 28.12 25,97
;J> Anorthite 14.74 8.64 27,68 31.42 17.39 26,10 19,46 12.99 25.03 31.08 38.89 24,84 24,73 25,44 23.31
"0
DioJlside - - - - - - - - - - 2,08 2.70 - 1.00 7.97"0
('b Wollustonite - - - - - - - -::J - -
x0-' Hypersfbene 4.67 7.97 7.72 11.11 10,19 10,92 9.39 11.59 12,38 16,65
11.96 14,77 14.57 9,15
Chromite 0.24 0.03 0.03 0.03 0.03 0.03 0,04 0.04 0,06 0,07 0,04 0.06 0,07 0.06 0.05
IjJ
Haematite 10.35 14,94 9.59 10,90 11.35 12.24 11.03 11.77 10,22 12,00 8.95 11.34 11.95 12,26 10,14
hj Ilmcuite 0,21 0.30 0,27 0.30 0.28 0,32 0.24 0,23 0,20 0,29 0,11 0,25 0.29 0,30 0,27
o 1
0\ Sphene - 0,30 1.84 1.41 -- - 1.33 3,29 3.60 3,30 3,57 37
Apatite 0,34 1.62 1.54 1.70 1.66 1.67 1.73 2.14 2,21 2,40 1.92 2,04 2,06 2.05
31'.971
Rutile - 0.98 1.34 0,48 0.73 1.34
\ 1.32 1.43 1.66 1.68 1.23 - 0,11 -
-
KFN2-4 KFN2-S KFN2-6 KFN2~7 KFN2-8 KFN2-9 MAI-I MAl-lO MAl-li MAI-12 MAI-13 MAI-l4 MAl-IS MAI-16 MAI-17
Depth (metres) 728.87 739.60 748.20 758.62 774.51 7S! 21 853.20 971.65 972.92 987.00 1,005.50 1,029.70 1,053.17 1,100.00 1,125.14
Formation Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat
Unit 5 4 4 4 .4 5 Sediment 3 ?3 3 3 3 3 3 Intrusive
wt.% ,
sro, 56.63 54.11 52.1.4 49.61 50.96 5448 76.51 44.01 55.85 51.00 51.14 49.87 52.66 49.44 75.27
'1'1°1 . 1.46 1.62 1.45 1.66 1.73 1.51 1.07 1.74 1.34 1.49 1.52 1.51 1.44 1.55 0.56
AI10J 15.89 16.2j 15.61 18.00 16.78 15.05 5.53 15.91 13.71 13.32 13.99 14.07 13.83 14.81 8.47
FelO) 10.00 10.03 10.15 12.52 11.27 10.44 10.20 11.10 8.60 10.51 11.29 11.51 9.68 10.93 6.73
MnO 0.10 0.12 0.12 0.12 0.1 I 0.12 0.12 0.12 0.06 0.12 0.13 0.13 0.12 0.15 0.05
MgO 4.24 4.18 3.83 4.92 4.72 4.11 1.85 5.86 0.37 4.82 5.60 5.67 4.92 5.51 1.11
CaO 3.46 4.44 7.14 3.24 5.11 ,7.20 3.11 7.23 15.30 7.36 6.64 7.03 8.30 7.73 0.82
NalO 3.48 3.86 3.59 3.62 3.53 2.75 0.01 3.45 0.01 2.95 3.28 3.12 2.93 3.13 0.01
KlO 0.31 0.19 0.28 0.29 O.I I 0.67 0.02 0.02 0.05 0:04 0.04 0.18 0.81 0.69 4.38
P105 0.67 0.74 0.67 0.72 0.81 0.74 0.14 0.91 0.77 0.79 0.82 0.81 0.78 . 0.81 0.15
H10- 0.08 0.07 0.06 0.08 0.11 0.06 0.01 0.04 0.01 0.10 0.07 0.07 0.03 0.06 0.03
LOl 3.55 4.14 6.34 3.63 3.62 2.92 3.56 6.76 1.64 4.83 2.52 2.45 2.14 2.52 1.25
TOT 99.87 99.73 101.38 98.41 98.86 100.05 102.13 97.l5 97.71 97.33 97.04 96.42 97.64 97.33 98.83
ppm
Rb 6.90 3.00 6.60 10.90 1.50 14.40 0.01 0.01 9.30 0.01 0.01 2.00 17.60 14.90 100.80
Ba 203.00 204.10 218.50 338.90 136.30 968.20 14.90 46.60 89.20 59.20 87.30 351.50 1,306.90 753.90 4,311.30
Sr 432.80 462.60 428.30 477.80 587.00 684.70 35.70 274.10 5,482.60 433.50 490.80 526.90 468.80 467.80 114.40
Zr 328.40 366.00 336.30 370.60 363.90 335.10 133.20 261.60 86.80 225.20 228.90 221.50 225.70 248.70 188.70
Nb 14.60 16.30 15.40 17.30 16.90 17.30 13.00 13.30 15.00 12.20 13.20 12.70 13. to 14.10 10.00
Ni 53.00 52.40 50.90 61.90 87.80 74.40 320.70 120.90 28.80 99.60 114.20 118.20 100.70 97.10 53.30
Zo 96.20 88.00 70.80 104.50 110.50 89.20 64.70 97.70 9.90 109.50 92.80 81.60 78.00 112.10 43.20
Cr 152.30 155.60 136.70 174.00 246.60 191.90 1,098.60 321.70 209.50 286.50 318.00 299.10 251.50 226.10 162.80
Cu 7.60 21.10 7.40 11.10 11.50 22.00 129.60 10.40 30.00 49.50 21.80 16.60 24.30 i 34.40 12.60
V 226.70 225.10 229.40 276.60 242.70 205.90 130.80 227.90 190.20 235.60 229.50 227.40 207.60 I 218.20 73.50
Y 38.00 43.20 41.60 41.80 46.10 42.60 i2.50 37.10 44.00 38.00 37.10 36.30 35.20 . 38. la 22.50
Sc 21.20 16.70 19.40 16.50 19.70 19.20 19.70 20.90 26.60 22.40 21.60 21.90 19.40 22.40 7.90
Co 40.00 46.00 37.80 57.50 58.30 43.60 103.00 59.50 17.40 52.30 55.20 57.10 50.40 47.90 24.50
CIPW Norms. (%)
Quartz 24.17 17.98 1·2.82 15.93 14.92 17.76 68.32 2.45 32.62 16.02 13.25 11.69 13.09 8.35 56.42
Corundum 5.28 3.47 - 7.91 3.60 0.17 - - - - . 2.31
Zircon 0.07 '0.07 0.07 0.07 0.07 0.07 0.03 0.05 0.02 0.05 0.05 0.04 0.05 0.05 0.04
Ortboelase 1.91 1.18 1.75 1.81 0.69 4.08 0.12 OJ3 0.31 0.20 0.25 1.14 5.02 4.31 26.58
Albite 30.59 34.19 31.98 32.35 31.40 23.97 0.08 32.52 0.08 27.14 29.38 28.12 25.97 27.95 0.08
>- Anortbite 13.50 18.22 27.04 12.26 21.34 27.63 14.74 31.08 38.89 24.84 24.73 25.44 23.31 25.73 4.33
"0 Diopside - 0.81 . - . - 2.08 2.70 - 1.00 7.97 3.47
"0
G Wollastonite - - - - - -
:::l
c.. Hyperstbene 10.97 10.90 9.67. 12.94 12,36 10.54 4.67 16.65 - 11.96 14.77 14.57 9.15 12.88 2.83
>< Cbromite 0.03 0.03 0.03 0.04 0.05 0.04 0.24 0.07 0.04 0.06 0.07 0.06 0.05 0.05 0.03..... Haematite 10.39 10.50 10.69 13.22 i1.85 10.76 10.35 12.00 8.95 11.34 11.95 12.26 10.14 11.54 6.90
Ilmeriite 0.22 0.27 0.27 0.28 0.25 0 ..27 0.21 0.29 .~ 0.11 0.25 0.29 0.30 0.27 0.34 0.11
oN Spbene - - 3.40 - 2~-3r ,- - 1.33 3.29 3.60 3.30 3.57 3.37 3.58 -
-...l Apatite 1.66 1.84 1.67 1.81 2.02 1.82 0.34 2.40 1.92 2.04 2.06 2.05 1.97 2.04 0.43
Rutile 1.40 1.55 1.61 1.69 0.07- O~ L___I.p . ..- 0.1 I - - 0.52
l\IAI-18 MAI-19 MAI-2 MAI-20 MAI-21 . MAI-3 MAI-4 MAI-S MAI-6 MAI-7 MAI-8 MAI-9 MA2-1 MA2-10 MA2-11
Depth (metres) 1,142.18 1,162.98 858.30 1,177.00 1,210.00 870.98 882.78 893.18 905.00 935.11 946.12 965.32 919.51 1,085.87 1,097.22
Formation Rietgat Rietgat Rietgat Rietgat Rietgai Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat
Unit I 1 5 I 1 5 5 5 4 5 4 3 5 3 3
wt.%
SIOl 54.97 55.92 58.15 53.56 53.98 57.67 53.07 56.79 53.37 56.46 54.99 54.68 58.00 49.77 49.78
'1'101 . I. I'} 1.26 .1.44 1.33 1..35 1.31 1.37 1.43 1.42 1.50 1.72 1.71 1.36 1 1.67 1.55
A110J 13.08 13.75 14.00 13.97 13.53 14.31 14.34 15.01 14.85 14.96 15.83 14.75 14.22] 14.59 14.51 ,
FelOJ 9.61 9.42 14.37 8.82 7.21 9.19 10.24 10.91 11.67 10.62 11.35 9.79 7.99 10.62 10.96
MnO 0.13 0.12 0_13 0.11 0.10 0.12 0.13 0.12 0.14 0.11 0.10 0.09 0.10 0.11 0.11
MgO 4.19 3.55 3.08 4.03 3.08 2.97 4.19 3.93 4.18 3.63 4.49 4.76 2.78 5.62 5.30 I
CaO 6.13 5.64 2.50 6.05 7.43 6.63 7.17 4.20 5.87 4.67 3.65 5.96 4.92 7.44 7.46
NalO 1.51 2.51 0.03 2.80 2.74 2.34 1.06 0.89 2.43 3.30 3.39 3.12 0.69 2.96 3.30
K,O 2.92 2.16 1.84 2.38 2.55 0.69 1.66 2.14 0.72 0.33 0.06 0.04 2.65 0.06 0.08
PlO, 0.52 0.55 0.95 0.59 0.60 0.62 0.67 0.67 0.67 0.70 0.87 0.89 0.63 0.88 0.82
H2O- 0.03 0.04 0.02 0.07 0.05 0.02 0.05 0.07 0.04 0.05 0.05 0.06 0.08 0.08 0.01
LOl 3.38 3.38 5.17 3.18 5.41 5.17 7.39 5.21 5.83 4.42 3.57 4.69 5.64 3.40 2.51
TOT 97.66 98.30 101.38 96.89 98.03 101.04 101.34 101.37 101.19 100.75 100.07 100.54 99.06 97.20 96.39
ppm
Rb 70.80 52.70 58.40 55.20 58.40 21.10 59.50 79.00 26.70 6.80 0.01 0.01 91.60 0.40 0.01
Ba 1.450.60 1,154.30 604.00 1,114.60 892.30 193.20 643.70 877.60 323.70 153.40 60.50 65.40 1,006.10 103.20 130.70
Sr 619.20 467.60 41.10 455.50 416.20 414.00 88.20 73.40 151.00 303.40 264.80 579.10 81.50 526.50 775.80
Zr 312.70 335.60 324.00 352.30 340.30 296.70 318.70 318.70 317.10 321.30 346.50 268.30 318.00 247.10 226.30
Nb 16.60 16.70 15.80 17.40 16.10 13.30 15.70 14.10 15.00 14.20 16.90 14.50 13.60 13.70 12.90
NI 103.60 84.00 53.10 96.50 67.90 50.50 60.70 65.90 56.10 72.40 82.20 103.50 49.30 120.90 127.60
Zo 99.10 94.10 83.30 98.00 86.50 97.80 87.90 85.70 96.60 129.20 97.50 92.00 65.40 89.80 104.20
Cr 379.30 347.70 148.90 373.20 228.50 130.20 147.50 153.20 161.90 206.80 207.60 275.40 127.50 328.30 313.60
Cu 34.50 29.60 12.10 27.20 27.10 24.20 10.30 6.20 5.80 7.10 5.40 6.00 14.80 8.50 24.20
V 166.20 198.30 230.50 180.00 181.40 207.10 226.80 249.90 229.50 234.70 253.90 255.70 221.30 255.80 229.30
y 40.80 42.50 32.60 42.40 44.70 35.80 39.00 33.00 36.10 38.90 44.20 42.50 32.00 40.80 40.70
Sc 17.20 19.70 21.60 17.70 19.40 16.50 18.90 18.90 21.60 18.50 18.90 20.40 21.90 25.10 19.20
Co 47.20 47.10 64.60 40.00 35.70 37.80 45.70 53.90 56.20 47.70 53.70 48.40 39.50 53.10 54.10
CIPW Norms. (%)
Quartz 19.54. 19.07 44.42 13.24 13.82 26.06 22.51 31.57 20.45 23.35 23.77 19.76 33.00 12.24 10.84
Corundum - 9.27 - - - 5.33 1.01 2.40 5.81 0.84 2.89 - -
Zircon 0.06 0.07 0.07 0.07 0.07 0.06 0.06 0.06 0.06 0.06 0.07 0.05 0.06 0.05 0.05
Orthoclase 18.34 13.48 11.33 15.05 16.31 4.26 10.47 13.19 4.47 2.03 0.37 0.25 16.81 0.38 0.50
Alblte 13.35 22.38 0.26 25.30 25.04 20.65 9.55 7.83 21.57 29.00 29.74 27.56 6.25 26.72 29.75
>- Aoorthite 21.61 21.02 8.64 19.84 18.49 27.68 31.42 17.39 26.10 19.46 12.99 25.03 22.03
28.15 26.18
-c Diopside 2.93 0.77 3.14 9.98 . · . . 1.99-c
(1) Wollastooite . . . . · .
::I Hyperathene 9.72 8.97 7.97 9.27 3.67 7.72 11.11 10.19 10.92 9.39 11.59 12.38 7.42 14.94 13.14Cl.
x' Chromite 0.08 0.07 0.Q3 0.08 0.05 0.03 0.03 0.03 0.03 0.04 0.04 0.06 0.03 0.07 0.07
v.> Haematite 10.20 9.93 14.94 9.42 7.79 9.59 10.90 11.35 12.24 11.03 11.77 10.12 8.56 11.33 11.68
Ilmeaite 0.28 0.25 0.30 0.23 0.22 0.27 0.30 0.28 0.32 0.24 0.23 0.20 0.23 0.25 0.25
IoV Sphene 2.76 2.95 0.30 3.20 3.30 1.84 1.41 · . . . 3.75 3.73
00 Apatite 1.32 1.39 1.62 1.51 1.54 1.54 1.70 1.66 1.67 1.73 2.14 2.21 1.61 2.23 2.08
Rutile - - 1.34 . . 0.48 __ 0.E..._ 1.34 1.32 1.43 1.66 1.68 1.33 0.12
~!2'
MA2-12 MA2-U MA2-14 MA2-IS MA2-16 MA2-17 MA2-18 MA2-2 MA2-3 MA2-4 MA2-S MA2-6 MA2-7 MA2-8 MA2-9
Depth (metres) 1,122.85 1,137.19 1,156.85 1,165.12 1,177.50 1,187.65 1,204.21 938.77 948.21 954.47 962.65 988.39 1,015.92 1,044.47 1,067.35
Formation Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat
Unit 3 3 3 3 TufT 2 I 5 5 4 5 5 3 5 3
wt.%
SIOl 42.64 47.67 50.50 51.11 43.97 56.56 54.17 58.33 54.61· 46.68 53.46 51.54 52.11 54.49 49.76
rro, . 1.63 1.42 1.46 1.4~ 0.20 1.26 1.28 1.40 1.35 1.84 1.40 1.60 1.68 1.24 1.67
Al,O) 16.23 13.90 14.72 14.79 2.94 13.43 13.67 14.54 14.20 20.68 14.89 14.51 14.83 13.74 14.67
Fe10) 11.84 10.74 11.17 10.28 6.08 8.58 9.75 7.94 9.23 8.58 8.71 11.19 11.17 9.59 12.10
MnO 0.13 0.11 0.13 0.15 0.12 0.12 0.12 0.10 0.12 0.14 0.10 0.11 0.11 0.11 0.13
MgO 5.95 5.42 5.56 5.59 1.69 314 3.70 3.01 3.40 3.14 2.79 4.48 4.62 3.81 5.97
CaO 7.89 7.17 7.44 8.41 23.42 5.15 6.04 4.62 5.57 6.50 6.10 4.98 4.20 5.97 4.59
NalO 1.78 3.65 4.27 3.68 0.01 2.20 2.52 2.62 2.55 0.14 2.64 2.66 2.97 2.65 2.77
KlO UQ 0.07 0.0(, 0.10 0.03 2 87 2.29 1.47 0.83 5.18 1.19 0.29 0.04 2.17 0.23
PlO~ 0.83 0.72 (J.73 0.77 0.07 052 0.55 0.65 0.64 0.93 0.67 0.79 0.85 0.54 0.86
HlO- 0.05 0.10 0.10 0.10 0.04 0.01 0.05 0.06 0.07 0.09 0.03 0.06 0.07 0.06 0.03
LOl 6.37 2.58 2.58 2.34 19.02 3.30 3.63 4.7.9 5.69 7.00 5.73 4.96 4.14 5.29 4.73
TOT 96.93 93.55 98.72 98.81 97.59 97.14 97.77 99.53 98.26 100.90 97.71 97.17 96.79 99.66 97.51
ppm
Rb 37.60 0.10 0.50 0.30 0.01 6840 51.90 52.40 27.40 203.50 47.10 10.70 0.01 1.70 3.10
Ba 2,884.20 104.20 140.50 137.10 36.20 1,798.20 1,313.00 640.00 412.10 2,346.80 610.60 184.10 66.10 115.00 527.90
Sr 528.30 434.90 411.00 536.90 193.50 545.90 614.30 139.70 166.70 80.50 288.40 340.00 285.70 551.10 271.70
Zr 245.90 226.10 228.60 230.80 61.30 387.30 316.40 327.50 306.10 420.30 318.60 313.30 265.70 255.20 255.30
Nb 14.40 12.70 13.00 11.90 5.80 18.30 16.50 15.00 12.90 19.60 15.00 16.30 13.70 13.70 14.00
Ni 113.60 111.30 101.80 100.70 14.80 61 10 92.90 51.30 61.00 82.40 59.70 82.10 108.60 106.50 110.70
Zn 113.90 76.90 83.00 82.20 42.00 86.80 99.90 84.40 94.80 212.70 94.20 118.20 12UO 115.80 122.10
Cr' 395.50 289.00 250.70 231.90 62.10 27670 311.40 135.30 153.00 176.30 158.10 199.00 295.80 271.90 334.10
Cu 12.30 23.80 21.70 27.50 13.20 22.30 28.90 9.70 7.30 97.30 5.60 8.30 15.00 22.10 15.80
V 229.30 210.10 210.40 206.10 21.90 16460 192.40 235.50 232.60 280.10 232.30 245.20 272.30. 254.30 236.20
Y 37.40 35.40 34.80 35.70 12.29 3960 40,60 33.40 36.00 57.70 38.40 42.60 36.50 40.30 37.00
Sc 20.90 20.90 16.20 22.60 18.00 1820 21.20 21.90 19.70 26.80 22.10 22.10 20.70 18.90 18.50
Co 50.80 56.40 48.10 44.60 12.50 37.10 48.70 38.70 43.90 36.50 43.20 55.00 56.00 56.20 61.00
CIPW Norms. (%)
Quartz 4.06 7.45 10.02 8.22 18.54 2048 16.22 26.20 23.05 9.49 19.87 21.67 22.83 16.18 17.76
Corundum - - .. - 1.83 0.50 4.88 - 2.72 4.61 - 3.68
Zircon 0.05 0.05 0.05 0.05 . 0.01 008 0.06 0.07 0.06 0.08 0.06 0.06 lOS 0.05 0.05
Ortboelase 10.21 0.46 0.56 0.61 0.22 18 Il 14.41 9.20 5.31 33.26 7.67 1.87 .25 . 13.60 1.54Albite 16.66 33.99 34.17 32.31 0.11 19.84 22.66 23.41 23.33 1.32 24.29 24.40 27.14 \ 23.78 25.48
>- Anortbite 34.84 23.51 22.87 24.45 10.05 19.60 20.51 19.94 25.52 29.08 27.52 21.31 . 16.63 20.37 18.67
"0 Diopside - 4.42 6.24 7.08 11.56 0.36 2.98 - - - - - 2.65 -
"~0 Wollastonite - - - - - - - - - - -
::l
c.. Hypersthene 16.42 12.81 10.64 11.17 8.17 8.42 7.92 9.15 8.54 7.56 12.30 12.43 8.84 16.11
x' Chromite 0.08 0.06 0.05 0.05 0.01 0.06 0.07 0.03 0.03 0.04 0.03 0.04 0.06 0.06 0.07
w Haematite 13.00 11.82 10.02 10.67 7.74 9.14 10.36 8.39 9.98 9.22 9.47 11.91 12.06 10.17 12.72
Ilmenite 0.27 0.26 0.29 0.34 0.32 0.26 0.26 0.23 0.28 0.36 0.24 0.29 0.25 0.25 0.30
oN Spbene 1.89 3.50 3.38 3.36 0.21 2.99 3.01 - - - 0.63 - - 2.91 -
'C Apatite 2.23 1.88 1.89 1.90 0.21 1.33 1.40 1.64 1.64 2.40 1.74 2.07 2.18 1.36 2.23
Rutile 0.84 - - - - _.~ - 1.36 1.31 1.76 1.14 1.55 1.68 - 1.62
i'f
MALI-I MALI-lO MALI-II MALI-2 MALI-3 MALI-,I MALI-S MALI-6 MALI-7 MALI-8 MALI-9 MAL4-1 MAL4-2 MAL4-3 MAL4-4
Depth (metres) 702,35 860,75 895.36 706.85 713.65 721.'20 731.26 760.42 799.50 818.96 834.75 759.61 778.80 809.12 830.37
Formation Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat
Unit 5 I 1 5 5 4 5 5 1 1 1 4 5 5 5
wt,%
sro, 53.03 57.86 57.30 51.03 55.37 46.~4 54.62 51.80 54.24 62.21 61.28 49.71 54.47 57.29 56.83
T10l . 1.45 1.35 1.20 1.57 1.55 1.55 1.43 1.61 1.30 . 1.32 1.30 1.38 1.33 1.47 1.49
AllO) 14.78 14.63 13.57 14.99 14.88 16.53 14.61 14.89 14.08 13.65 12.97 14.26 14.32 13.97 13.45
FelO) 10.72 9.39 9.78 9.64 9.49 11.23 10.09 11.16 8.90 7.66 7.46 10.21 8.42 9.39 9.12
MnO 0,11 0:10 0.12 0.14 0.11 0.15 0,13 0.10 0.12 0.09 0.10 0.13 0.12 0.10 0.10
MgO 3.71 3.56 4.97 4.13 4.47 5.23 3.44 6.42 3.16 4.01 3.34 5.58 3.25 3.37 4.27
CaO 6.71 6.62 6.84 7.29 5.22 7.20 6.47 4.84 5.84 3.52 6.67 6.14 5.60 3.78 5.01
NalO 0.71 2.88 1.91 3.04 3.01 2.45 2.57 2.58 3.44 3.40 2.73 0.78 2.53 3.11 3.15
KlO 2.t6 O.lt 1.43 0.23 0.21 0.21 0.84 0.05 0.12 0.17 0.17 1.68 1.11 0.40 0.24
PlO, 0.70 0.59 0.53 0.73 0.73 0.78 0.72 0.86 0.57 0.57 0.57 0.63 ',0.61 0.69 0.71 ,
HlO- 0.08 0.06 0.03 0.10 0.13 0.06 0.03 0.12 0.09 0.07 0.08 0.10 (1.06 0.05 0.07
LOl 6.95 3.55 3.42 6.52 5.06 6.97 5.87 5.00 4.97 3.38 4.20 7.21 5.45 3.27 3.27
1
TOT 101.11 100.70 101.10 99.41 100.23 99.50 100.82 99.43 96.83 100.05 100.87 97.81 97.27 96.89 97.71
ppm
Rb 78.80 0.01 21.90 3.80 1.30 3.50 30.40 0.01 0.01 0.01 0.01 56.10 37.10 8.30 2.20
Ba 1,480.00 214.90 1,739.90 166.50 141.00 ' 162.20 678.10 87.70 139.80 245.90 301.00 693.60 687.00 542.80 352.80
Sr 126.60 656.20 1,273.90 255.90 228.20 303.20 460.80 356.20 410.30 506.40 504.20 109.50 303.00 627.10 597.40
Zr 330.30 337.80 284.10 337.00 336.00 348.70 319.00 234.60 323.90 338.00 323.10 337.60 321.70 318.90 327.00
Nb 16.60 15.50 14.30 15.90 14.80 15.90 14,90 11.90 14.90 14.40 14.50 15.70 14.20 14.40 16.00
Ni 71.10 &1.80 103.70 72.00 73.70 88.90 70.80 127.50 81.20 97.40 70.20 53.60 50.80 80.30 71.90
Zo 74.40 87.50 110.10 111.60 79.20 90.30 122.30 97.00 102.70 88.20 52.80 79.70 98.70 115.40 98.30
Cr 190.20 378.60 423.50 224.40 222.00 232.10 200.40 364.20 190.90 355.00 382.20 134.10 129.70 248.50 220.80
Cu 13.50 29.30 28.60 291.10 18.80 5.80 30.80 15.50 32.80 16.20 10.20 41.70 7.20 17.10 12.60
V 222.10 188.10 173.30 223.30 239.50 267.90 225.70 266.00 211.90 194.00 156.60 218.00 211.20 213.90 211.00
Y 40.40 38.90 39.70 41.20 38.80 43.90 39.30 38.00 42.60 36.20 33.00 36.40 37.00 37.70 39.00
Sc 22.40 16.70 17.00 21.20 21.40 25.30 18.00 22.60 21.60 19.40 18.50 19.70 18.20 19.40 23.90
Co 39.10 42.10 43.00 43.30 47.30 4960 48.60 56.60 44.10 52.20 35.30 40.10 36.90 48.10 46.70
CIPW Norms, (%)
Quartz 23.94 23.99 21.82 14.81 22.32 1167 20.80 20.17 20.34 30.81 24.98 20.93 22.08 28.16 23.70
Corundum 0.67 - - - 2.03 120 - 4.04 - 2.86 - - 0.17 3.31 0.54
Zircon 0.07 0.07 0.06 0.07 0.07 007 0.06 0.05 0.07 0.07 0.07 0.07 0.06 0.06 0.07
Ortboelase 13.60 0.67 8.66 1.47 1.31 1.34 5.24 0.31 0.77 1.04 1.04 10.99 7.17 2.53 1.50
Albite 6.39 25.09 16.55 27.72 26.80 22.42 22.91 23.15 31.72 29.78 23.91 7.29 23.33 28.12 28.24
>- Anorthite 30.69 27.51 24.95 28.67 22.35 33.27 27.29 19.65 24.68 14.47 23.47 29.34 26.23 15.59 21.73
-0 Diopside - 2.59 - - - - - 2.23 - -
-0
Cl> Wollastonlte - - ..::s - - - - - -
0- Hypenthene 9.82 9.13 11.48 11.09 11.71 14.09 9.03 16.95 8.57 10.34 7.58 15.36 8.82 8.97 11.27
x Chromite 0.04 0.08 0.09 0.05 0.05 0.05 0.04 0.08 0.04 0.08 0.08 0.03 0.03 0.05 0.05
w Haematite 11.40 9.67 10.02 10.39 9.99 12.14 10.63 11.83 9.70 7.93 7.72 11.28 9.18 10.04 9.66
- Ilmenite 0.25 0.20 0.24 0.32 0.25 0.35 0.29 0.22 0.28 0.19 0.19 0.31 0.28 0.23 0.22tv Sphene 1.86 2.73 3.74 - 1.35 - 2.13 - 3.06 - -o Apatite 1.78 1.45 1.31 1.87 1.82 2.00 1.81 2.17 1.47 1.41 1.40 1.66 1.58 ' 1.76 1.79
Ruti1e 1.41 0.53 - - 1.50 :1'.60 __ 0.80 ~ . 0.40 1.27 1.36 1.30 1.45 1.46
MAL4-5 MAL4-6 MAL4-7 MAL4-8 NVTI-IO NVTl-II NVTI-12 NVTI-13 NVTI-14 NVTI-15 NVTI-16 NVTI-17 NVTI-18 NVTI-19 NVTI-2.
Depth (metres) 840.71 858.21 869.42 889.91 1,347:31. 1,354.95 1,367.13 1,379.49 1,387.18 1,397.89 1,411.07 1,420.27 1,430.37 1,440.06 1,313.00
Formation Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat
Unit 3 3 '3 3 4 4 . 4 4 4 5 5 3 3 3 4
wt.%
S101' 50.77 50.42 49.64 57.54 49.97 52.51 52.49 51.53 52.68 53.18 47.43 46.98 51.09 49.78 48.39
no, '1.58 i.54 1.47 1.48 1.5'5 1.59 1.46 1.58 1.51 1.41 1.75 1.94 1.78 1.82 1.54
AllO, 14.04 13.63 15.18 14.27 15.22 15.79 15.75 16.54 15.54 14.54 15.97 17.34 15.97 15.77 18.46
FelO, 11.50 11.80 10.07 9.56 9.62 10.52 7.86 11.22 9.53 7.94 11.56 11.30 12.00 12.08 10.03
MnO 0.12 0.12 0.09 0.11 0.15 0.14 0.10 0.15 0.13 0.08 0.11 0.11 0.11 0.12 0.24
MgO 6.33 5.90 5.53 3.36 4.83 4.51 1.70 3.94 3.19 2.25 4.36 4.23 4.81 5.04 4.06
CaO 5.73 7.45 6.96 3.83 4.91 2.93 6.35 3.26 4.84 7.10 6.19 6.03 4.13 3.89 6.88
NalO 3.00 3.05 2.94 3.33 3.83 4.40 5.02 3.48 4.37 3.81 3.86 4.39 3.18 3.94 0.02
KlO. 0.03 0.04 O.OS 0.40· 0.6S 0.'17 1.32 1.94 '0.92 2.24 0.13 0.27 0.91 0.73 2.S5
PIOS 0.81 0.83 0.74 0.69 0.69 0.69 0.68 0.72 0.70 0.67 0.88 0.98 0.89 0.90 0.75
HIO- 0.10 0.09 0.06 0.06 0.03 0.07 0.10 0.08 0.08 0.06 0.04 0.07 0.07 0.05 0.01
LOl 3.38 i.04 4.07 3.10 5.03 3.31 4.79 3.42 4.22 5.40 4.88 3.73 3.63 3.81 7.60
ITPOT~~ 97.39 96.91 96.80 97.73 96.48 96.:':i 97.62 97.86 97.71 98.68 97.16 97.37 98.57 97.93 100.53Rb om 0.80 0.01 0.01 20.00 10.10 32.60 56.40 30.10 59.60 6.30 7.70 29.60 22.00 110.30
Ba 80.10 130.70 261.60 89.70 917.30 24BO 1,466.00 4,461.30 1,032.50 1,688.10 194.50 314.50 1,712.20 1,211.30 813.10
Sr 569.10 768.90 695.50 884.90 264.00 240.90 312.80 336.20 371.10 395.00 698.10 1,093.90 471.30 284.60 57.60
Zi' 253.60 221.00 235.70 208.70 359.70 362.00 345.10 373.00 360.50 328.50 337.70 361.60 319.30 322.90 372.20
Nb 14.00 14.30 13.30 11.40 17.00 l7.00 16.20 18:90 17.90 16.00 18.80 19.10 18.60 17.90 19.90
Ni 107.00 119.70 112.00 129.70 49.60 66.70 34.20 58.70 51.70 21.80 94.50 87.40 107.10 104.30 70.50
Zn 100.60 100.00 100.10 83.80 205.70 439.00 50.20 132.90 88.20 58.30 135.60 98.80 112.50 121.00 146.00
Cr 271.40 305.10 38J..10 376.00 148.30 I 59.riO· 133.10 149.40 147.90 124.00 217.20 229.40 273.20 280.90 129.50
Cu 19.70 25.50 27.80 20.10 21.80 42AO 31.40 48.60 13.60 13.10 6.40 6.10 9.50 4.50 25.20
V 242.00 225.40 247.20 233.70 231.60 279.00 235.50 256.60 244.40 217.90 257.00 305.80 286.60 299.20 247.10
Y 39.70 38.20 36.30 34.40 41.10 41.40 37.80 42.80 39.30 36.20 46.40 52.90 44.10 39.00 35.50
Sc 21.60 20.90 17.20 18.20 13.30 24.30 19.10 15.70 16.30 16.10 15.80 22.90 18.30 15.80 26.60
Co 57.60 57.70 54.30 51.30 40.80 62 ..30 39.50 46.60 57.10 25.40 46.60 5UiO 55.70 51.90 56.30
CIPW Norms. (%)
Quartz 14.57 12.45 15.97 10.60 10.18 15.31 6.66 13.34 11.17 9.50 7.67 4.01 16.21 11.27 21.22
Corundum 0.56 - 2.74 - 0.93 4.87 - .4.41 0.13 - 027. 1.14 4.43 3.69 5.26
Zircon 0.05 0.04 0.05 0.04 0.07 . 0.)7 0.07 0.07 0.07 0.07 0.07 0.07 0.06 0.06 0.07
Orthoclase 0.19 0.25 0.51 0.32 4.2.1 1.71 8.42 12.17 5.83 14.23 0.84 1.71 5.68 4.59 16.26
Albite 27.03 27.23 26.96 30.18 35.44 39.88. 45.81 31.20 39.58 34.58 35.41 39.70 28.36 35.43 0.19
~ Anorthite 24.86 24.71 24.79 28.10 22.05 10.89 17.90 13.41 21.21 17.18 27.37 25.61 16.07 14.67 31.70
-0 Diopslde - 2.89 - - 5.22 - 8.99 - - - -
-0
!'I> Wcllastonite - - - - - - - - - - -
:l
0- Hypeesthene 16.79 14.16 13.17 15.07 13.16 -12.0'3 7.15 10.40 8.50 1.86 11.77 11.26 12.63 13.34 10.88
X Chromite 0.06 0.07 0.08 0.08 0.03 0.03 0.03 0.03 0.03 0.03 0.05 0.05 0.06 0.06 0.03
w Haematite 12.25 12.45 11.80 10.67 10.52 11.27 8.48 11.89 10.20 8.52 12.53 12.08 12.65 12.84 10.79
lImenite 0.28 0.27 . 0·24 0.20 0.35 0.3,3 0.23 0.34 0.30 0.18 0.26 0.25 0.25 0.27 0:56IV
Spbene - 3.64 - 2.69 - 3.58 - - 3.50 - - - 1"
Apatite 2.05 2.08 2.27 1.94' 1.80 1.:76 (75 1.90 1.79 1.72 2.27 2.50 ,:.26 2.30 1.92
Rutile 1.54 - 1.68 0.39 1.51 1.49'. 1.94 1.74 1.79- i."53 L_ ---- L_ _ ____!& - 1.76 1.36
:"-,-4.-;"
NVTl·20 NVTl·20A NVTl·21 NVTl·22 NVTl·22A NVTl·23 NVTl~24 NVTl·2S NVTl·26 NVTl·27 NVTl·28 NVTl·29 NVTl·30 NVTl·32 NVTl·33
Dt(llh (metres) 1,442.10 1,454.17 1,472.82 1,485.83 1,499.63 1,51fv5 1,533.50 1,548.20 1,556.61 1,567.19 1,579.46 1,590.89 1,599.23 1,625.27 1,638.55
Formation Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat
Unit 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
wt,%
SI02 49.93 47.21 46.25 48.27 53.51 53,66 52.13 51.92 50.64 50.27 52.27 49.31 50.55 47.79 57.12
TlOI . 1.80 1.76 1.72 1.74 1.66 1.68 1.54 1.52 1.55 1.49 1.52 1.50 1.48 1.58 1.67
AllO) 15.70 15.55 15.68 15.14 14.03 14.00 13.66 14.23 14.07 13.65 14.23 14.27 13.85 14.89 14.25
FelO) 11.70 12.64 11.92 11.71 11.28 9.'12 10.79 10.07 11.16 10.67 10.65 11.84 9.32 11.62 7.65
MnO 0.11 0.12 0.12 0.11 0.11 O. :0 0.15 0.12 0.14 0.14 0.12 0.16 0.16 0.17 0.09
MgO 4.77 5.32 4.97 5.17 5.11 4.:i3 5.18 3.68 5.56 5.35 6.66 5.92 4.36 5.81 3.55
CaO 4.39 5.58 7.63 6.40 3.64 6.66 7.77 8.89 7.35 8.79 7.64 7.'27 10.85 7.37 5.54
N'alO 3.85 3.20 3.38 3.03 2.06 3.:18 3.87 3.19 3.06 3.38 3.10 3.22 4.57 3.62 5.12
KlO 0.67 0.12 0.08 0.60 1.83 o.ss 0.20 1.27 0.84 0.57 0.78 0.76 0.39 0.98 0.83
P10S 0.89 0.88 0.87 0,89 0.84 039 0.80 0.78 0.81 0.19 0.79 0.79 0.78 0.79 0.83
H10· 0.06 0.15 0.12 0.05 0.08· . 0.1)5 0.05 ,0.04 0.06 0.05 0.03 0.12 0.10 0.13 0.06
LOl 3.72 4.21 5.34 4.88 3.65 2.1)8 2.80 2.89 2.47 2.52 2.45 2.83 2.55 2.71 1.79
TOT 97.59 96.74 98.08 97.99 97.80 98.:14 98.94 98.60 97.71 97.67 100.24 97.99 98.96 97.46 98.50
ppm
Rb 21.50 5.60 3.90 18.40 55.90 27.10 8.00 42.50 26.00 18.70 24.90 24.80 12.70 29.60 22.40
Ba 1,202.50 169.60 147.50 993.40 2,904.10 769.60 343.20 1,320.30 1,163.90 693.40 1,239.90 950.40 357.90 855.60 497.20
Sr 477.00 585.70 611.40 466.00 257.60 505.1)0 54UO 1,153.90 618.10 657.90' 723.00 458.30 731.20 449.80 414.30
Zr 312.10 298.10 285.60 289.00 286.4() 272.20 243.20 226.70 229.10 222.80 232.00 227.70 221.00 257.80 271.70
Nb 17.90 17.40 15.00 16.60 16.00 15.90 15.30 15.80 14.30 14.40 15.30 14.50 13.90 15.40 13.60
Nl 101.20 119.50 112.00 117.30 100.70 102.10 112.00 113.20 123.70 127.00 124.90 134.10 113.50 113.00 109.80
Zo 114.50 111.80 108.20 125.10 128.40 100.20 95.90 89.50 106.80 101.50 124.00 116.30 7'i7.60 108.60 86.40
Cr 254.90 256.20 254.60 283.40 265.10 292.70 255.00 261.00 295.70 293.10 292.30 323.00 269.40 274.10 234.10
Cu 7.40 19.70 18.40 11.20 16.00 47.~0 16.40 25.20 16.30 38.70 93.10 19.50 41.20 18.30 194.80
V 294.90 273.50 280.10 266.10 260.20 250.·50 241.10 212.10 257.50 224.80 242.40 264.70 235.60 231.90 211.50
Y 38.40 39.60 40.40 41.50 35.70 36.20 37.60 37.70 36.80 35.70 38.30 35.30 35.10 36.60 30.60
Sc 16.90 15.00 17.80 17.40 19.90 20.~O 20.10 22.20 30.20 24.10 21.90 24.50 21.00 27.60 22.10
Co 51:90 60.80 53.90 55.00 52.40 39.50 48.70 44.10 53.40 48.20 50.30 54.60 37.30 54.30 46.70
CIPW Norms, (%)
Quartz 11.50 11.50 6.43 10.04 22.51 11.48 10.10 10.41 10.20 8.05 9.46 7.66 1.96 2.97 11.52
Corundum 2.83' 2.21 · . 4.06 . · · · · · . . ·
Zircon 0.06 0.06 0.06 0.06 0.06 '0.05 0.05 0.05 0.05 0.04 0.05 0.05 0.04 0.05 0.05
Ortboelase 4.23 0.77 0.51 3.82 11.52 5.48 1.23 7.86 5.23 3.55 4.73 4.74 2.40 6.13 5.09
A1bite 34.72 29.31 30.87 27.55 18.53 34.12 34.07 28.21 27.20 30.70 26.83 28.67 40.15 32.37 44.82
>- Anorthite 17.50 23.99 29.60 27.95 14.19 18.92 20.13 21.77 23.37 21.48 23.20 23.46 16.77 22.76 13.95
"0 Diopside · . · . 3.17 7.68 11.47 3.75 1l.28 4.63 3.61 22.96 4.44 2.73
"0
ti> Wollastonite · . · · ·::; · · · . ·
0.. Hypeesthene 12.66 14.34 13.36 13.84 13.53 10.26 9.87 4.29 12.82 8.79 14.83 13.84 0.64 13.24 7.89
X Chromite 0.05 0.06 . 0.05 0.06 0.06 0.06 0.05 0.06 0.06 0.06 0.06 0.07 0.06 0.06 0.05
v.' Haematite 12.47 .. . 13:68 12.87 12.58 11.99 10.31 11.23 10.53 1l.73 11.22 10.89 12.46 9.68 12.28 7.91
llmenite 0.25 0.29 0.28 0.26 . 0.25 022 0.34 0.27 0.32 .0.32 0.27 0.36 0.35 0.39 0.20
N Sphene · 3.81 0.25 . 402 3.50 3.57- 3.60 3.44 3.49 3.42 3.32 3.61 3.99
N Apatite 2.28 2.27 2.23 2.28 2.18 2,21 1.98 1.95 2.03 1.98 1.93 - 1.98 1.92 1.99 2.05
Ruti1e 1.79 1.75 0.16 1.64 1.63 -.. · · · · · . . ·
:"'-',,~
NVTI-34· NVTI-3S NVTl-36 NVTl-37 NVTl-38 NVfl-3~) NVTi-4 NVTl-40 NVTl-44 NVTl-46 NVTl-47 NVTl-48 NVTl-49 NVTl-S NVTI-SI :
Depth (metres) 1,657.24 1,665.50 1,677.24 1,714.10 1,726.17 1,132.13 1,316.86 1,750.26 1,800.67 1,818.27 1,847.12 1,859.75 1,874.10 1,318.62 1,890.871
Formation Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat
Unit 3 3 3 3 3 j 4 3 2 2 2 2 \ 2 4 I
wt.% ,
SlO, 52.20 51.10 49.99 49.46 48.12 50..16 57.20 51.17 60.90 54.69 58.47 58.90 '. 55.93 55.90 56.77
TIO, . 1.49 1.54 1.56 1.68 2.02 1.79 '1.38 1.61 1.16 1.31 1.38 1.30 1.32 1.28 1.44
A1,0) 13. 70 13.87 14.45 13.25 14.61 13.79 15.09 13.66 13.00 13.99 14.22 13.82 13.70 14.13 15.08
Fe,O) 9.85 10.99 11.67 11.74 13.63 12.75 7.i2 12.34 8.59 8.14 8.43 8.11 8.06 6.83 9.19
MnO 0.12 0.15 0.13 0.13 0.17 0.19 0.1.2 0.16 0.12 0.10 0.09 0.09 0.10 0.13 0.11
MgO 3.33 3.90 3.84 l54 5.74 4.')0 2.28 4.38 2.25 ·2.60 2.95 2.97 2.22 2.14 2.70
CaO 7.95 7.63 7.82 9.35 6.27 7.18 6.37 7.85 4.46 6.41 3.10 4.06 5.92 7.22 6.02
Na,O 2.76 2.95 3.23 2.68 2.87 3.29 0.07 2.43 0.70 3.20 3.16 3.23 3.50 0.03 3.20
K,O 1.46 1.98 0.87 1.19 0.10 0.59 3.41 1.25 2.46. 1.27 2.19 1.82 1.81 3.34 2.34
P,Os 0.77 0.78 0.78 0.86 1.02 VI 0.63 0.84 0.45 0.52 0.52 0.51 0.53 0.60 0.61
H,O- 0.06 0.01 0.06 0.07 0.04 0.,)9 0.04 0.03 0.09 0.02 0.08 0.05 0.11 0.02 0.06
LOl 4.74 2.65 4.43 4.57 2.91 2.57 6.52 2.78 4.99 5.79 3.33 3.88 5.32 7.30 0.41
'fOT 98.43 97.55 98.83 98.52 97.50 98.51 100.83 98.50 99.17 98.04 97,92 98.74 98.52 98.92 97.93
ppm
Rb 43.80· 56.10 24.00 33.30 4.80 17.10 137.00 31.50 112.50 57.90 54.70 52.60 48.20 140.60 53.10
Ba 1,571.40 1,'721:60 703.70 95i90 111.50 712.20 997.20 916.40 559.90 624.00 1,234.70 1,019.70 842.20 1,025.20 830.30
Sr 689.90 578.60 620.10 533.20 248.70 553.40 58.60 496.30 72.50 282.40 308.60 348.80 298.20 70.70 211.50
Zr 237.90 242.10 239.10 272.50 325.60 281.10 340.50 262.80 384.90 421.10 425.80 415.40 397.90 335.40 349.80
Nb 14.60 15.30 13.30 71.10 18.90 16.80 15.40 15.90 16.50 18.50 19.00 18.50 18.80 15.90 16.70
NI 97.80 95.20 94.10 64.60 75.70 74.60 42.20 72.30 39.10 43.80 48.80 52.50 61.10 40.40 99.40
Zo 93.90 110.20 115.90 149.40 104.80 132.00 49.60 119.70 86.10· 92.00 111.10 96.70 84.50 42.20 87.50
Cr 196.60 195.60 207.00 128.40 145.30 122.20 117.90 137.40 198.70 234:50 276.50 239.70 270.00 111.10 427.50
Cu 50.90 26.30 30.50 35.80 21.00 31.40 7.40 29.80 16.60 13.90 17.00 19.00 19.70 18.00 17.70
V 202.50 222.70 249.00 240.80 282.10 287.70 235.20 246:40 163.20 175.70 204.00 186.50 197.70 206.20 224.40
Y 33.30 35 ..10 35.30 39.80 43.20 39.00 32.10 37.50 31.00 37.20 41.60 37.80 39.80 35.60 38.80
Sc 22.00 23.30 20.10 26.50 21.00 22.20 13.40 24.00 11.20 14.30 13.30 15.00 13.90 16.90 13.80
Co 44.10 47.50 52.60 47.10 59.00 51.00 22.10 . 52.00 36.40 28.80 36.60 37.60 34.60 26.80 37.40
CIPW Norms. (%) ;
Quartz 14.49 9.79 10.55 11.38 12.56 11.17· 30.05 14.11 37.91 18.21 23.23 22.45 17.32 ~, 29.04 15.61
Corundum - - - 0.84 - 1.20 - 2.23 - 2.26 0.28 -
Zircon 0.05 p.05 0.05 0.05 0.07 0.06 0.07 0.05 0.08 0.08 0.09 0.08 0.08 0.07 0.071
Ortboelase 9.23 12.36 ·5.46 7.51· 0.63 3.65 21.43 7.73 15.50 8.16 13.72 11.37 11.51 21.60 14.21 .
Albite 24.94 26.30 28.97 24.16 25.68 29.04 0.63 21.49 6.29 29.36 28.29 28.83 31.81 0.28 27.78
;J> Anorthite 22.16 26.30 23.i5 21.99 25.97 22.08 29.44 23.75 20.57 21.78 13.11 18.12 17.58 31.21 20.43 I
-0 Diopside 7.96 8.04 5.58 12.62 - 2.77 - 5.01 .- 3.68 - - 4.70 - 1.29
-~0 Wollastonite - - - - - - - - - - - -
::l
0- Hypentbene ·5.18 6.53 7.55 3.56 15.12 1145 6.02 9.08 5.95 5.32 7.77 7.80 3.77 5.82 6.30
X Cbromite 0.04 0.04 0.04. 0.03 0.03 003 0.03 0.03 0.04 0.05 0.06 0.05 0.06 0.02 0.09
w Haematite 10.52 11.58 12.37 12.51 14.42 Jj 30 8.19 12.90 9.13 8.83 8.92 8.55 8.66 7.46 9.43
Ilmenite 0.28 0.35 0.30 0.30 0.40 0.44 0.27 0.36 0.26 0.21 0.18 0.19 0.30 0.21
N
Sphene 3.56 3.55 3.68 4.01 - 4,93 - 3.68 - 3.21 03.2."1 I 2.76 3.36
w Apatite 1.97 1.97 1.97 2.18 ·2.56 2,,26 1.59 2.09 1.14 1.34 1.33 1.29 1.36 1.56 1.49
Rutile - - 1.93 - 1.32 - 1.09 -. 1.36 1.27 0.12------ -
-_",:1'.:~
NVTI-52 NVTI-S3 NVTI-6 NVTI-7 NVTI-8· NVTl-9 POEI-l POEI-2· POEI-3 POEI-4 POEl-S POEl-6 S4-1 S4-10 S4-11
Depth (metres) 1,910.00 I~940.82 1,322.89 1,326.68 1,337.00 1,341.09 749.95. 765.29 778.20 799.10 818.68 848.21 736.18 809.00 811.76
Formation Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat. Rietgat
Unit I I 4 4 4 4 5 5 5 5 5 Tuff 5 5 5
wt.%
SiO, 57.33 60.87 55.05 54.94 53.75 52.84 56:08 52.97 55.77 56.41 56.04 68.88 50.33 51.73 52.50
no, '1 31 1.29 1.28 1.38 1.61 1.58 1.46 LSO 1.41 1.44 1.44 1.62 1.45 1.39 1.42
AI,O) 13.87 13:86 14.13 15.09 16.34 16.76 14:45 14.33 14.04 14.72 14.08 10.13 14.25 14.21 14.11
F.e,O) 10.46 6.36 7.86 9.33 10.12 9.72 10.61 11.02 9.79 10.10 9.34 8.19 12.18 , 12.03 9.25
MnO 0.12 0.10 0.11 0.1 i 0.14 0.13 0.13 0.15 0.12 0.11 0.12 0.09 0.11 0.14 0.12
MgO 2.83 2.04 2.84 3.28 5.28 5.07 S:16 S.48 3.94 4.16 3.88 3.44 6.35 5.21 2.57
CaO 3.77 4.52 6.73 4.99 2.58 3.55 5.11 5.41 7.67 5.57 6.57 2.43 6.49 6.30 8.70
Na,O 2.86 2.16 0.60 3.18 3.98 4.32 1.37 2:14 2.01 1.96 2.77 0.01 0.01 0.91 1.58
K,O 1.68 2.34 2.95 0.98 0.39 0.24 1.38 0.49 .1.40 1.76 2.11 3.98 1.55 1.29 1.74
P,Os 0.55 0.48 0.59 0.62 0.69 0./1 0.7Ó 0.72 0.71 0.70 0.71 0.25 0.72 0.69 0.70
H,O- 0.02 0.13 0.02 0.03 0.05 0.06 0.09 0.11 0.09 0.11 .0.05 0.08 0.11 0.06 0.05
LOl 3.77 4.38 6.98 4.99 3.38 4.00 S.88 5.79 . 3.88 3.79 2.96 2.68 8.13 6.97 7.71
tOT 98.57 98.53 99.14 98.92 98.31 98.~8 102.42 100.11 100.83 100.83 100.07 101.78 101.68 100.93 100.45
ppm
'Rb 43.50 140.30 143.80 47.60 17.50 9.~0 60.50 19.30 29.00 38.30 49.40 101.80 47.70 . 47.60 49.80
Ba 717.00 652.60 1,223.10 521.90 270.70 172.~0. 501.80 181.00 927.40 871.00 1,050.80 2,909.60 442.70 409.50 347.50
Sr 144.00 273.50 80.90 169.00 207.20 210.10 122.40 245.60 655.80 540.90 664.90 92.60 91.70 141.80 190.20
Zr 341.30 616.90 331.40 337.50 367 ..10 369.70 319.90 329.10 310.90 309.90 306.70 188.10 326.50 314.90 325.70
Nb 15.2Q 25.50 16.40 15.60 16.30 17.00 15.40 15.90 16.30 15.4Ó 15.90 10.80 15.40 15.70 16.00
NI 82.50 20.30 44.30 52.10 56.90 53..~0 78.00 74.00 66.70 68.40 73.00 54.40 74.20 71.60 71.70
Zn 111.90 67.20 7L10 75.80 90.30 75.20 103.40 123.50 101.60 100.90 94.70 55.20 104.50 122.60 96.90
Cr 409.80 59.30 12L10 135.90 154.40 153.30 218.50 190.70 161.40 230.00 205.60 118.40 185.50 209.90 190.30
Cu 25.90 10.00 16.30 32.60 25.50 19.10 26.20 23.40 31.70 20.20 23.00 58.20 26.20 20.20 5.90
V 237.90 141.50 211.70· 245.60 283.50 275.90 226.80 223.50 191.80 206.00 194.50 210.40 225.30 228.90 213.60
Y 33.30 52.50 36.40 35.70 40.20 40.20 37.60 40.70 41.60 38.20 40.20 34.10 34.10 38.10 38.90
Sc 19.20 8.80 16.30 14.10 19.90 20.60· 20.70 16.00 20.40 16.20 12.80 17.70 17.20 16.00 20.40
Co 42.10 23.20 33.00 38.20 37.40 39.90 48.00 53.80 41.60 44.60 43.90 34.50 52.10 52.00 43.60
CIPW Norms. (%)
Quartz 24.69 25.59 25.71 19.98 18.53 14.19 27.03 22.12 20.74 22.63 16.12 44.09 24.53 23.54 20.23
Corundum 1.83 0.67 - 1.23 6.63 4.85 3.15 2.26 - 1.05 1.77 2.61 . 1.56 -
Zircon 0.07 0.12 0.07 0.07 0.07 0..)7 0.06 0.07 0.06 0.06 0.06 0.04 0.07 0.06 0.07
Ortheelase 10.50 14.76 18.98 6.19 2.44 ·1.50 8.48 3.08 8.55 10.75 12.87 23.79 9.82 8.14 I LIl
Albite 2~.53 19.43 5.51 28.66 35.49 38.51 12.01 19.22 12.56 17.11 24.15 0.08 0.09 8.20 14.43
>- Anorthite 16.18 20.78 29.52 22.25 8.88 1379 21.72 23.63 26.03 24.21 20.41 11.33 29.57 28.64 28.36
"0
"0 Diopside - - - - - 3.04 - 3.28 - . 6.70
(1) Wollastonite - - - - - - - . - -::l
c.. Hyperathene 7.44 5.40 7.68 8.70 13.86 13.30 13.32 14.49 8.56 10.69 8.44 8.65 16.93 13.82 3.80
X Chromite 0.09 0.01 0.03 0.03 0.03 0.03 0.05 0.04 0.03 0.05 0.04 0.03 0.04 0.05 0.04
Vol Haematite 11.04 6.76 8.53 9.94 10.67 10.24 11.00 11.70 10.11 10.42 9.62 8.27 13.03 12.81 9.98
-N I1menite 0.24 0.23 0.26 0.25 0.32 0.29 0.29 0.34 0.27 0.24 0.26 0.20 0.26 0.32 0.28~ Sphene - 2,04 - '~::: - - 3.24 - 3.31 - 140
Apatite 1.38 1.22 ~1.53- 1.57 1.73 )..i8 1.73 1.81 1.75 1.72 1.75 0.62 1.83 1.75 1.79Rutile 1.25 ).25· 1.34 1.53 J.5.1 1.36 1.41 - 1.36-- - - 1.42 1.31
_! .;~r:t~~
S4-12 S4-13 S4-14 S4-15 S4-16 S4-17 S4-2 S4-3 S4-4 S4-8 S4-9 S5-12 S5-13 S6-1 S6-IB
Depth (metres) 821.07. 831.11 843.87 855.70 867.10 838.:!0· 744.17 750.72 755.13 794.28 800.85 822.85 869.55 738.25 742.00
Formation Rietgat Rietgat Rietgat Rietgat RIetglit Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietglit Rietgat
Unit 5 5 5 5 5 3 5 4 5 4 5 5 3 4 5
",t.%
sio, 55.42 55.95 54.52 55.98 56.03 50.1:5 51.53 . 55.44 53.99 36.53 50.36 53.77 48.04 50.65 44.91
TIO, . 1.41 1.44 1.41 1.40 1.44 Uil 1.38 1.54 1.41 1.81 1.39 1.44 1.55 1.94 1.39
AI,OJ 15.38 14.32 13.69 14.45 14.23 14.liO 14.24 15.20 13.72 17.61 13.99 13.69 14.21 18.63 14.75
Fe,OJ 9.21' 9.51 9.93 9.94 10.14 10.37 8.68 11.02 9.79 29.18 9.98 9.81 11.45 7.65 8.15
MnO 0.11 0.13 0.12 0.14 0.14 0.1 I 0.10 0.09 0.11 0.22 0.11 0.13 0.11 0.08 0.12
MgO 2.78 3.60 3.80 3.94 3.94 5.. 7 4.4~ 6.06 3.22 4.62 3.51 3.98 5.09 4.64 4.69
CaO 8.71 7.86 7.50 8.36 6.56 6:i5 8.68 3.43 7.07 3.52 9.25 7.16 6.83 . 5.48 12.00
Na,O 1.92 2.68 1.92 2.02 2.87 }.:!8 0.02 0.02 1.72 0.01 0.84 2.38 2.54 0.05 o.oi
K,O 1.71 0.47 1.16 1.37 1.83 0.11 2.41 2.09 0.96 0.85 2.10 1.22 0.21 4.55 3.01
PlO! 0.74 0.70 0.68 0.70 0.72 0.a5 0.71 0.73 0.68 0.82 0.70 0.69 0.78 0.95 0.73
H,O- 0.05 0.05 0.04 0.03 0.05 0.04 0.07 0.1) 0.06 0.10 0.06 0.13 0.08 0.06 0.17
LOl 7.35· 4.56 3.58 3.48 2.89 5.39 9.28 5.88 6.12 5.75 8.84 3.84 4.90 6.19 11.42
TOT 104.79 101.27 98.35 101.81 100.84 99.13 101.55 101.61. 98.85 101.02 101.13 98.24 95.79 100.87 101.35
ppm
Rb 60.70 9.70 25.70 29.90 41.70 om 75.80 65.20 33.60 32.20 84.70 23.80 5.90 155.10 96.20
Ba 490.50 479.10 701.30 690.20. 778.20 120.30 502.40 617.50 190.40 273.40 467.40 1,077.90 360.50 1,077. 70 577.90
Sr 242.70 792.60 646.80 762.20 722.30 400.10 123.70 63.80 412.40 47.70 206.90 717.00 688.30 42.70 88.60
Zr 316.50 307.80 313.60 300.60 315.30 257.40 325.60 342060 313.50 391.30 318.10 309.00 218.80 457.00 330.80
Nb 14.70 16.20 16.60 15.60 16.30 13.50 15.70 16.50 14.66 23.80 15.90 15.50 13.00 19.40 16.10
Ni 62.10 71.80 73.50 75.60 76.00 10610 70.20 69.60 70.80 98.60 69.40 18.30 20.00 66.00 64.20
Zn 109.30 99.20 100.20 102.10 105.80 94.10 71.80 90.20 105.30 195.50 101.00 73.60 117.70 50.60 49.40
Cr 183.10 203.60 206.70 200.30 207.30 28).0)0 172.30 212.80 185.50 277.20 175.40 107.90 115.40 248.90 182.80
Cu 23.10 31.20 27.60 30.00 32.50 23.50 23.20 27.SP 26.30 19.00 23.50 28.80 42.40 36.10 12.60
V 207.80 200.80 194.00 189.80 199.50 247.50 214.80 242.40 212.20 319.20 200.90 44.40 40.20 291.60 203.20
Y 39.90 40.90 41.60 41.60 43.00 39.80 38.70 32.90 38.90 36.60 40.60 186.20 316.20 55.10 39.90
Sc 19.70 19.90 19.40 21.90 18.70 21.40 22.90 19.40 18.50 18.50 19.70 192.20 188.80 24.60 19.20
Co 40.00 40.60 45.50 48.00 43:80 52.90 37.90 46.30 46.40 96.50 39.80 38.50 45.70 34.70 31.50
Cli'W Norms. (%)
Quartz 19.61 20.82 22.03 19.69 16.24 13.03 22.08 34.41 24.85 22.li 18.56 18.72 14.18 17.76 8.56
Corundum - -. - - - - 8.74 - 12.83 -. - 6.18 -
Zircon 0.06 0.06 0.06 0.06 0.06 0.05 0.07 0.07 0.06 0.08 0.06 - 0.09 0.07
Ortheelase 10.40 2.88 7.43 8.25. 11.06 0.69 15.48 12.9'5 6.14 5.29 13.49 7.65 1.37 24.48 19.85
Albite 16.68 23.46 16.58 17.39 24.81 29.62 0.19 0.18 15.70 0.09 . 7.71 . 21.36 23.67 0.45 0.09
>- Anortbite 29.08 26.60 26.97 26.82 21.04 26.48 34.35 12.99 29.03 12.81 30.59 24.47 29.46 22.47 34.90
"'0
"'0 Diopslde 4.62 3.71 2.31 5.28 2.57 - 2.12 - - - 7.50 2.84 - 16.69
('1)
::s Wollastonite - - - - - - - - - -
0x.' Hyperstbene 4.97 7.56 9.10 7.54 8.84 13.74 11.04 15.78
8.65 12.09 6.01 9.20 13.96 12.21 5.28
Chromite 0.04 0.04 0.04 0.04 0.04· 0.06 0.04 0.05 0.04 0.06 0.04 - - 0.05 0.04
VJ Haematite 9.46 9.84 10.49 10.11 10.36 11.07 9.41 11.52 10.56 30.66 10.82 10.41 12.61 8.09 9.08
N- lImenite 0.24 0.28 0.28 0.31' 0.31 ~~., "QJ,3 ~~Q)Q~ Q)6 0.50 0.26 0.29 0.26 0.17 0.28Sphene 3.25' 3.30 3.25 3.11 3.23 3.38 2.98 - 3.37 3.37 1.58 - 3.44\Jl
Apatite 1.81 1.72 1.73 1.70 1.75 2.15 1.83 1.82 1.74 2.05 1.80 1.13 2.03 2.40 1.93
Rutile - 0.58 1.51 0.17 1.64 0.93 1.96-- -- - -
,
~~~: 'it{ ··1';
S6-2 S6-3 S6-3A S6-3B S6-3C S6-3D S6-3E S6-3F S6-5 S6-7 S6-8 TKI/I TKI/IA TKI/I B TKI/2
Depth (metres) 747.10 800.70 833.89 759.62 773.61 790.15 823.00 836.65 841.75 863.90 890.00 Outcrop Outcrop Outcrop Outcrop
Furmatlen Rielgal Rielgal Rielgal Rietgal Rielgal Rietgat Rietgat Rietgat Rietgat Rietgai Rietgat . Sodium Gp. Sodium Gp . Sodium Gp. Sodium Gp.
Unit 5 5 5 5 5 5 . 5 5 5 5 I ? ? ?1 ?
\\'t.%
SIO,. ~~.76 ~S.l>S %.)~ S4.44 57.01 ~6.1' 56.51 60.47 57.65 S4.71 56.69 49.17 87.65 72.40 53.06
TiO, 1.40 1.42 1.53 . 1.60 1.45 1.49 i.43 1.34 1.26 1.50 1.22 0.90 0.26 0.42 1.08
Al,O)· 14.08 14.36 14.60 14.50 14.40 14.21 14.22 13.42 13.99 13.65 13.29 13.30 6.27 11.23 14.79
Fe,O) 9.78 9.92 10.39 10.72 9.38 10.11 10.49 9.32 10.02 10.61 9.45 8.76 1.25 4.62 9.08
MnO 0.12 0.14 0.11 0.14 0.12 0.13 0.12 0.12 0.12 0.14 0.11 0.16 0.01 0.04 0.11
MgO 3.26 4.10 4.45 5.69 3.63 3.64 4:27 3.66 4.37 6.06 3.99 5.31 0.54 2.51 3.65
CaO 7.52 7.13 4.90 4.66 7.15 6.50 7.11 5.42 5.76 6.31 6.18 8.19 0.13 0.86 4.44
Na,O 1.87 2.44 2.89 2.35 2.33 2.12 2.19 2.74 2.87 2.43 2.15 1.77 0.69 0.74 4.42
K,O 1.03 1.20 1.61 0.32 1.47 1.22 1.53 1.13 1.87 0.97 2.17 0.86 1.71 2.69 0.69
P,O! 0.69 0.69 0.74 0.75 0.71 0./2 0.71 0.66 0.55 0.80 0.54 0.36 0.04 0.07 0.41
H,O- 0.04 0.09 0.12 0.07 0.04 OJ7 0.09 0.07 0.06 0.07 0.06 0.09 0.02 0.03
Lal 6.28 3.56 2.73 5.20 3.93 H9 2.82 3.29 2.32 2.96 3.35 8.26 1.07 2.60 4.60
TOT 101.83 100.70 100.45 100.44 101.62 100:':;9 101.49 101.64 100.84 100.21 99.20 97.04 99.71 98.20 96.36
ppm
Rb 34.60 24.00 37.70 9.70 28.80 23.('0 34.00 23.50 23.00 45.10 57.20 25.30 55.70 93.50 10.80
BR 545.00 548.20 936.80. 149.80 1,242.90 620.~0 625.50 556.50 1,349.70 758.90 1,003.10 209.20 614.10 805.60 909.10
Sr 372.00 547.90 469.30 271.50 691.40 445.(10 496.60 567.10 41.0.9.0 685.60 987.10 235.90 11.90 30.70 315.20 I
Zr 309.20 305.60 334:00 334.00 316.30 316.~0 315.70 289.20 244.20 304.40 314.50 134.50 229.30 321.10 228.20
Nb' 15.50 15.30 16.90 15.10 16.40 15.1:0 17.20 14.50 14.20 15.70 15.80 7.40 5.40 12.60 10.10
Ni 68.10 74.00 74.30 73.50 66.00 63.110 72. ro 70.00 102.40 101.20 93.10 150.00 4.40 10.50 97.60 I
Zn· 102.40 108.30 87.40 129.70 103.60 104.00 113.00 80.40 106.50 132.60 102.00 133.90 12.10 41.80 122.20 I
Cr 176.10 224.10 218.6'0 194.70 177.90 205.:;0 192.80 183.50 236.60 360.40 345.80 382.3'0 13.60 13.90 238.90
Cu 24:60 24.20 17.8'0 8.40 30.~0 21.00 26.10 10.00 25.90 23.00 25.50 39.40 0.90 4.00 106.60
V 195.50 196.50 218.60 248.10 195.80 199.10 190.70 . 172.50 222.80 190.10 164.80 202.40 12.40 24.10 229.30
y 39.10 40.40 42.70 42.00 40.40 36.20 39.20 38.00 39.00 38.30 41.00 20.80 12.00 21.80 28.80
Sc 17.00 16.70 17.70 22.90 17.70 14.30 17.70 14.80 22.60 18.50 17.70 20.90 1.20 3.80 18.40
Co· 42.90 46.00 46.80 51.20 46.00. 43.10 48.60 41.10 47.40 49.00 43.90· 45.20 2.80 14.00 47.80
C1PW Norms. (%)
Quartz 24:18 '19.24 18.64 24.30. 20.40 23.04 19.84 25.70 17.79 17.51 20.43 14.87 76.38 54.28 12.37
'Corundum .0.86 3.75 - - - - 3.05 5.68
Zircon 0.06 0.06 0.07 0.07 0.06 0.16 0.06 0 ..06 0.05 0.06 0.06 0.03 0.05 0.06 0.05
Ortheelase 6.38 7.31' '9.77 1.99 8.91 7.19 9.19 6.81 11.23 5.92 ri.41 6.19 11.16 17.41 4.71·
A1bite 16.57 21.27 25.05 20.89 20.19 18.62 18.80 23.59 24.66 21.16 18.99 16.15 5.67 6.26 39.26
>- Anorthite 28:29' 25.49 20.37 19.28 25.17 26.69 24.85 21.40 20.16 24.22 21.17 28.88 0.56 4.42 20.79
-0
-0 Diopside 1.34 1.65 - 1.78 - 1.S5 - 1.35 2.93 10.85 -
!'I>
:::l Wellasteuite - - - - - - - - -
0- Hypersthene 7.88 7.46 11.35 14.89 8.43 9.41 10.Q7 9.27" 10.43 15.53 9.02 10.02 '\52 6.60 10.12
X Cliromite 0.04 0.05 0.05 0.04 0.04 0.04 . 0.04 0.04 0.05 0.08 0.07. 0.08 - 0.05\
W
Haematite 10.24 10.22 10.65 11.26 9.61 10.49 10.64 9.48 10.18 10.92 9.86 9.64 ' 1.30 4.75 9.72 1
Ilmenite 0.27 0.31 0.24 0.32 0.27 0.29 0.26 0.26 0..26 0.29 . 0.23 0.34 0.04 0.11 0.25 .
.N..... Sphene 3.25 '3.20 - - 3.32 1.58 3.23 1.35 .2.81 2.16 2.84 2.18 90\
Apatite 1.72 1.69 1.81 1.87' 1.74 (78 1.71 1.60 1.34 1.96 1.35 0.95 0.13 0.20 1.028 1
Rutile - - 1.44 1.51 - 0:67 0.51 - 0.25 0.39 0.56-- .o..~ - - - -
;_~:;.;'~£
-
TKI/3 TKI/4 . TKI/4A TKI/5 TKI/5A TKI/5B TKI/6 TK2I1 TK2IIA TK2IIB TK2nA TK2nB TK212C TK212D TK212E
Depth (metres) Outcrop' Outcrop Outcrop Outcrop Outcrop Outerep Outcrop Outcrop Outcrop Outcrop Outcrop Outcrop Outcrop Outcrop Outcrop
Formation Sodium Gp. Sodium Gp. Sodium Gp.· Sodium Gp. Sodium Gp. Sodium Gp. Sodium Gp. Sodium Gp. Sodium Gp. Sodium Gp. Sodium Gp. Sodium Gp. Sodium Gp. Sodium Gp. Sodium Gp.
Unit ? ? 5 5 3 3 3 ? ? ? ?2 ? ?1 ? ?1
wt.%.
SiO, 53.15 74.20 50.95 52.00 51.63 51.~2 52.49 45.33 45.68 50.57 65.80 65.36 58.59 74.3 61.50
no, . 1.41 U.34 1.65 l.ó3 UK U4 1.53 1.64 1.75 1.56 0.71 0.56 0.99 0.6 0.94
AllO) 13.07 11.87 13.12 13.00 12.10 12.22 12.19 11.54 12.52 14.02 12.44 8.29 10.69 6.36 8.87
FelO) 9.92 3.19 10.77 11.22 11.69 11.(;2 11.02 14.12 16.44 10.77 5.06 16.62 17.47 13.09 17.82
MnO 0.10 0.04 0.15 0.23 0.17 0.20 0.16 0.20 0.19 0.12 0.09 0.16 0.18 0.13 0.17
MgO 4.42' 7.29 4.27 4.28 4.99 4.64 5.14 5.41 5.63 4.97 0.86 2.96 3.26 2.27 3.38
CoO 5.26 2.03 5.93 5.97 5.39 5.97 7.36 9.01 5.85 5.36 3.12 0.51 0.95 0.48 0.79
NOlO 2.27 0.13 2.90 2.00 1.74 1.89 1.91 0.76 0.36 2.50 3.52 0.01 0.01 0.01 0.01
KlO 0.76 3.51 0.23 1.22 0.61 1.22 0.83 0.13 0.59 0.54 3.22 0.24 1.33 0.04 0.10
PlO, 0.57 0.04 0.71 0.72 0.64 0.li7 0.66 0.23 0.23 0.25 0.19 0.07 0.11 0.04 0.07 I
HIO· 0.02 0.01 0.01 0.01 0.02 0.02 0.03 0.03 0.04 0.04 0.11 0.11 0.07 0.06 0.07
LOl 5.72 3..68 5.82 4.80 6.01 6,;4 4.30 7.99 7.68 6.10 3.18 2.95 3.37 2.36 3.37
TOT 96.67 106.33 96.51 97.08 96.57 97.05 97.62 96.39 96.96 96.80 98.30 97.84 97.02 99.74 97.09
ppm
Rb 29.70 202.20 6.30 25.00 17.00 24.60 19.50 7.40 27.50 13.80 64.40 5.90 3).80 2.00 5.30
Ba 463.60 420.90 499.20 1,232.30 555.50 1,514.20 640.60 . 94.90 295.70 181.70 1,387.70 131.90 593'.'10 77.10 92.80
Sr 224.00 28.60 200.30 415.70 167.10 240.20 401.80 72.80 52.90 78.70 91.00 11.00 17.60 7.00 8.90
Zr 349.50 683.50 257.70 249.80 241.50 236.40 237.20 150.80 167.30 206.40 380.50 201.00 331.20 209.30 279.50
Nb 15.80 33.20 13.80 14.30 13.00 13.40 14.80 10.40 11.60 9.10 11.10 11.70 18.70 11.80 16.90
Ni 72.30 6.70 135.60 100.20 141.10 13UlO 158.30 90.20 106.80 81.10 12.80 28.70 33.80 24.40 26.10
Zo 191.70 29.20 365.00 128.60 151.10 . 130.aO 160.50 144.30 165.40 132.80 49.60 181.60 194.20 142.50 201.80
Cr 191.80 4.50. 446.30 277.10 450.80 464.50 488.70 114.20 . 133.70 171.70 16.20 16.60 9.70 28.20 21.50
Cu 22.80 13.20 35.70 36.90 37.60 36.20 38.70 116.80 188.10 192.70 46.10 8.60 18.70 7.20 23.90
V 235.00 21.60 347.20 299.70 313.30 281.80 278.40 305.10 334.70 272.20 50.10 109.90 147.20 84.10 123.80
Y. 38.50 79.70 43.60 40.70 38.50 38.:W 41.00 35.40 33.30 29.60 21.30 13.30 28.40 12.50 27.40
Se 16.70 2.10 25.60 25.00 28.30 21.70 24.60 30.50 27.50 25.80 2.90 0.10 10.30 2.10 12.00
Co 45.10 9.00 56.60 51.20 57.30 55.20 . 60.50 60.60 75.60 51.30 14.50 59.60 60.20 47.40 61.30
CIPW Norms. (%)
Quartz 22.51 36.67 18.35 20.14 23.75 20.09 19.41 18.91 22.61 17.12 27.89 62.01 49.34 71.52 58.19
Corundum . 3.57 . . . - · . 0.47 . · 7.63 7.78 5.60 7.97
Zircon 0.07. 0.14 0.05 0.05' 0.05 O. )5 0.05 0.03 0.03 0.04 0.08 0.04 0.07 0.04 0.061
Ortboelase 5.18 20.52 1.70 8.42 4.20 8.48 5.71 0.78 4.02 3.71 21.40 1.62 9.00 0.29 0.63
Albite 20.24 . 0.97 26.13 17.57 15.67 17.J6 16.58. 7.00 3.27 22.51 29.92 0.08 0.35 0.08 0.09
>- Anorthite 25.47 9.64 24.82 24.82' 26.05 23.48 23.89 31.02 32.67 28.38 8.82 2.29 4.77 2.41 3.73
"'0
"'0 Diopside - 0.96 5.94 11.49 · - 3.99 - -
(1)
::s Wollastonite . - . . · · · ·
c..
x' Hypersthene 12.34. 25.24 11.81 11.62 13.94. 12.45 11.18 10.05 i5.94 13.78 0.56 7.91 8.85
5.96 8.99
Chromite 0.04 . 0.10 0.06 0.10 0.10 0.10 0.02 0.03 0.04 · . · 0.01w Haematite 10.75 2.94 1t.'74 11.98 12.68 11.86 11.78 15.67 18.22 11.71 5.24 17.52 18.44 13.26 19:031
IV Ilmenite 0.27 0.12 0.32 0.53 0.39 0.46 0.34 0.49 0.49 0.30 0.20 0.39 0.42 0.31 0.41
Sphene 0.69·. . 2.75 2.98 0.33 3:~5 3.63 3.99 · 0.40 1.66 .--.) ·
Apatite 1.50 0.08 1.87 1.86 1.66 1.73 1.68 0.63 0.61 0.65 0.48 0.17 0.27 0.09 0:791
Ruti1e 1.15 0.22..._.0.61 0.30 . 1.43 . · . 1.75 1.47 · 0.39 0.86 0.49 0.18
-"i,
-
TK2I2F TK2/2G TK2I2H TK2I2 I TNT2-1 D;T2-IO TNT2-13 TNT2-14 TNT2-15 TNT2-16 TNT2-17 TNT2-3 \TNT2-4· TNT2-5
\
Depth (metres) Outcrop Outcrop Outcrop Outcrop 725.87 946.05 986.06 1,021.62 1,036.28 1,055.69 1,071:00 747.65 76'2A9 778.86
Formation Sodium Gp. Sodium Gp. Sodium Gp. Sodium Gp. Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat
Unit 3 3 3 3 5 3 3 1 1 1 1 5 5 5
wt.%
SiO, 48.75 49.91 50.51 52.22 52.42 . 46.81 51.81 57.78 52.02 56.85 50.81 53.97 48.89 53.51
no, 1.07 1.07 1.17 0.94 1.27 1.35 1.49 1.29 1.30 1.26 1.52 1.42 1.35 1.38
Al,O, 14.72 14.62 15.62 12.40 14.04 16.01 14.19 13.58 14.45 12.86 14.42 14.12 13.62 13.81
Fe,O, 5.17 5.18 4.02 10.70 8.60 11.09 11.28 8.96 11.47 8.84 11.40 9.64 8.82 9.90
MoO 0.10 0.11 0.09 0.17 0.10 0.12 0.15 0.10 0.14 0.11 0.16 0.12 0.18 0.13
MgO 2.05 2.23 0.94 '6.90 3.93 2.69 4.57 3.76 6.43 4.45 . 4.49 4.18 3.95 3.43
CaO 10.84 10.19 9.82 6.79 7.62 17.03 7.19 5.39 4.80 5.40 7.61 4.78 8.78 6.87
NOlO 4.69 4.86 6.16 1.96 0.17 0.21 2.98 2.85 3.26 2.47 3.02 3.60 3.40 2.51
K,O 0.51 0.67 1.27 1.93 2.80 0.96 2.04 1.58 0.41 2.08 2.26 0.27 0.15 1.34
P,O, 0.42 ·0.42 0.47 0.36 0.61 0.77 0.79 0.55 0.56 0.55 0.78 0.66 0.65 0.67
H,O- 0.05 0.08 0.05 0.08 0.05 0.05 0.04 0.19 0.11 0.08 0.05 0.08 0.06 0.04
LOl 8.43 8.05 7.24 3.39 8.01 1.83 2.75 2.68 3.08 3.38 2.33 4.75 7.81 4.61
TOT 96.80 97.39 97.36 97.84 99.62 98.92 99.28 98.71 98.03 98.33 98.85 97.59 97.66 98.20
ppm
Rb 12.50 12.30 21.40 40.90 128.30 25.70 48.70 37.60 6.80 48.90 55.20 7.90 4.70 29.60
8a 396.90 602.10 1,237.60 2,233.40 945.70 506.20 1,729.10 794.10 316.30 867.30 1,984.00 147.80 144.50 1,762.20
Sr 422.00 323.10 365.60 424:60 74.80 1,810.60 564.70· 534.50 538.50 472.20 588.50 250.50 308.30 769.40
Zr 185.20 185.50 205.20 160.70 304.50 198.10 236.50 331.20 337.00 325.80 246.40 318.70 306.80 305.80
Nb 10.20 8.20 10.20 10.20 14.50 16.30 13.80 16.20 16.90 15.50 15.10 14.10 13.60 15.40
Ni 119.40 112.70 39.10 235.10 52.10 70.00. 89.90 97'.30 111.80 99.80 91.60 54.60 49.30 69.80
Zo 69.60 65.40 33.50 127.00 121.S0 51.20 114.00 94.40 111.30 95.90 111.10 123.60 99.80 107.60
Cr 355.70 380.40 198.60 697.30 123.30 173.10 205.00 347.70 355.50 406.60 195.90 170.40 140.00 200.60
Cu 10.70 5.70 10.30 39.90 21.00 51.00 33.90 24.80 16.90 28.80 32.50 7.20 9.10 28.70
V 210.50 180.80 197.00 205.00 198.10 252.70 212.90 174.70 202.90 173.80 211.70 234.00 184.10 200.30
Y 30.80 24.50 34.70 25.50 36.00 48.80 39.40 39.10 42.60 40.80 40.10 39.20 : 38.20 41.10
Sc 20.80 19.00 15.30 23.10 23.60 22.10 20.40 17.50 18.70 22.90 18.90 22.60 122.10 17.70
Co 23.50 27.60 15.80 57.50 36.90 27.20 48.40 46.80 57.00 4~.70 49.30 47.40 36.60 43.40
CIPW Norms. (%)
Quartz 1.78 2.11 12.78 23.09 12.3l 9.29 21.10' 13.79 1'1.9°; 6.81 18.68 10.56 18.45
Corundum - - - - - 1.24 0.82 - -
:Ureon 0.04 0.04 0.05 0.03 0.06 0.04 0.05 0.07 0.07 0.07 0.05 0.06 0.06 0.06
Ortheelase 3.42 4.44 8.34 12.10 18.12 5.86 12.51 9.76 2.56 12.97 13.87 1.72 0.99 8.48
Albite 44.93 46.07 57.43 17.57 1.57 1.83 26.13 25.16 29.08 22.03 26.49 32.84 32.04 22.07
>- Anorthite 19.96 18.06 12.49· 20.59 32.01 41.19 20.10 20.50 21.53 18.88 19.89 21.04 23.92 24.11
"'0 Diopslde 12.48 13.44 5.62 s:i5 0.63 14.92 5.77 - 1.36 7.68 12.12 2.94
"~'0 Wollastooite 7.64 6.20 11.44 - - - - - -;:l
0.. Hyperathene - - 14.41 10.40 - 9.13 9.77 16.89 11.05 8.05 11.22 5.34 7.77
X Chromite 0.09 0.09 0.05 0.16 0.03 0.04 0.04 0.07 0.08 0.09 0.04 0.04 0.03 0.04
W Haematite 5.85 5.80 4.46 11.3.4 9.39 11.43 11.69 9.35 12.09· ·9.32 11.82 10.39 9.82 10.58
- Ilmenite 0.22 0.24 0.20 0.36 0.24 .. 0.26 0.34. 0.2.1 0.31 0.23 0.36 0.28 0.43 0.30IV Sphene 2.69 . 2.63 2.00 3.10 3.08 3.37 2.86 2.98 3.42 - 3.14 3.2600 _.Apatite - - - 1.58 1.89 1.96 1.37 1.41 1.39 1.94 1.69 1.72 1.72
Rutile 1.13 1.12 1.24 0.92 - - 0.08 1.21 - - 1.38 - -
,g,
TNT2-6 TNT2-7 TNT2-9 ZTDI-IO ZTDI-ll ZTDI-12 ZTDI-13 ZTD1-14 ZTDI-4 ' ZTDI-S ZTDI-6 ZTDI-7 ZTDI-8 ZTDI~9
Depth (metres) 835.84 897.65 933. 97 345.20 346.80 362.00 370.00 370.90 282;40 290.30 294.20 304.80 323.30 330.80
,_Formation Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat Rietgat
Unit 3 3 3 3 3 3 3 3 5 5 5 5 5 5
,'"
wt.%
SIOl 50.81 50.21 48.53 57.09 54.84 48.16 57.66 58.02 67.33 53.57 64.49 57.18 57.18 47.37
1'101 1.61 1.42 1.27 1.27 1.37 I 1.25 1.34 1.32 1.35 1.20 1.38 1.46 1.56 1.59
AllO) 14.88 15.01 14.19 13.62 14.13 . 12.73 14.01 13.51 14.89 14.73 14.82 i5.29, 16.53 17.72
Fe1O) ,11.68 9.83 9.75 9.27 89 8.52 8.75 10.32 6.61 11.58 7.20 8.19 , 9.07 11.69
MnO 0.12 0.13 0.12 0.20 08..211 0.22 0.15 0.16 0.05 0.17 0.08 0.13 0.10 0.15
MgO 5.54 4.92 4.78 4.98 4.90 4.28 2.48 2.89 1.69 3.18 2.02 2.36 3.52 4.04
CaO 5.81 12.60 7.50 4.89 5.03 i 6.04 6.76 6.23 1.68 6.07 2.99 6.14 3.56 6.67
NOlO 3.71 2.51 1.34 2.16 1.98 1.92 2.99 2.43 3.45 3.18 3.56 4.19 4.13 3.21
KlO 0.09 0.09 3.82 1.70 2.10 1.81 1.31 1.05 1.86 0.31 1.80 0.65 0.70 0.34
P10S 0.84 0.79 0.77 0.53 0.56 0.48 0.55 0.53 0.55 0.55 0.58 0.61 0.63 0.66 I
H1O- 0.09 0.09 0.11 0.04 0.02 0.05 0.07 0.06 0.08 0.07 0.06 0.08 0.09 0.17
LOl 2.82 2.97 6.13 8.15 8.38 17.25 6.83 6.66 2.97 6.55 3.78 5.69 4.75 7.491
TOT 98.00 100.57 98.31 103.90 102.41 102.71 102.90 103.18 102.51 101.16 102.76 101.97 101.82 101.10
ppm
Rb 1.30 0.70 84.70 90.50 110.00 101.40 62.00 52.60 107.10 19.40 97.50 34.20 37.30 21.10
Ba 138.00 69.90 1,220.70 623.20 769.30 665.80 369.80 289.40 669.30 189.90 634.50 315.90 330.60 228.40
Sr 483.80 533.50 140.10 283.30 308.00 276.00 216.80 180.30 154.10 206.90 182.80 318.90 260.80 311.80
Zr 278.70 218.90 218.40 229.60 238.80 241.80 238.20 234.70 268.00 232.70 273.60 279.40 263.30 284.00
Nb 15.50 13.60 12.20 11.00 10.50 13,60 11.50 12.50 11.10 12.20 11.90 12.90 11.90 14.40
.,.;
Nl 105.60 106.00 101.80 61.50 67.60 59.80 51.00 56.20 39.10 66.60 46.30 54.20 82.20 88.50
Zn 110.80 84.90 us.io 113.70 107.30 117.80 99.50 114.00 77.50 132.00 88.50 108.50 135.90 171.10
Cr 243.20 241.20 231.50 236.10 247.50 214.60 216.20 209.00 263.70 222.40 270.50 261.40 274.50 288.80
Cu 19.70 18.50 11.70 11.90 14.80 18.60 68.60 43.30 54.00 8.70 69.90 30.40 38.10 9.90
V 256.10 209.60 172.40 265.20 271.20 277.70 254.10 245.30 240.50 228.10 253.00 244.60 324.10 317.60
Y 39.30 36.80 35.60. 32.20 31.40 36.20 29.30 33.70 29.00 30.60 28.40 35.40 30.30 38.40
Sc 19.90 22.60 22.90 21.20 17.90 25.60 20.60 22.70 12.20 16.50 18.80 21.10 17.70 23.50
Co 60.20 39.20 49.90 38.30 40.30 37.90 36.30 39.50 24.80 . 48.70 33.00 37.90 48.50 52.60
CIPW Norms. (%)
Quartz 10.99 9.37 7.96 22.45 19.82 15.60 21.36 25.55 35.65 19.02 29.31 17.14 19.89 9.48
Corundum 0.07 - 0.54 0.74 - -" - 5.42 - 2.93 - 4.08 1.57
Zircon 0.06 0.04 0.04 0.05 0.05 0.06 0.05 0.05 0.05 0.05 0.06 0.06 0.05 0.06
Orthoclese 0.56 0.54 24.55 10.53 13.25 12.57 8.09 6.45 11.09 1.95 10.79 4.01 4.28 2.16
Albite 33.01 21.78 12.31 19.09 17.82 19.02 26.35 21.31 29.35 28.46 30.45 36.85 36.03 29.07
>- Anorthite 24.76 30.20 . 23.31 22.01 22.99 24.35 21.83 23.71 4.99 26.47 11.40 21.85 14.15 30.99
"'C
"0 Diopside 18.91 6.02 2.55 4.11 0.59 0.85 -
:C:ls> Wollastonite - - -, - - - -
xc.'. Hypersthene 14.51. 3.81 10.15 12.96 12.98 11.30 4.53 7.19 4.23 8.38 5.09 5.72 9.04 10.77 !Chromite 0.05 0.05 0.05 0.05 0.06 0.05. 0.05' 0.05 0.06 0.05 0.06 0.06 0.06 07
w 0. 1
Haematite 12.28 10.08 10.59 9.69 9.46 9.98 9.11 10.70 . 6.65 1·2.25 7.28 8.51 9.35 12.51,
IV I1menite 0.28 0.29 0.28 0.44 0.47 0.54 0.09 0.38 0.15 0.27 0.21 0.34 .- .~~ ....• r, -.:;:;,.:..;;:.
0.32 '''!R'k'-<',-'<, 0.35.
\0 Sphene - -3.20 3.03 2.90 3:01' 2.91 1.21 3.38
Apatite 2.10 1.92 1.99. 1.32 1.42 1.34 1.36 1.30 1.33 1.38 1.40 1.51 1.55 1~681
Rutile 1.55 - 1.10' 1.21 - - _. UI 0.58 1.31 1.50 1.52
-
ER03-1 ER03-2 ER03-3 ER03-14 ER03-IS ER03-)·7 ER03-18 ER03-1, ER03-20 ER03-21 ER03-22 ER03-23 ER03-24 ER03-2S ER03-26
Depth (metres) 269.90 288.85 319.21 621.80 686.40 3~1.:;0 857.90 919.40 96~.85 1,021.75 1,083.42 1,144.60 1,204.55 1,259.17 1,402.18
Formation Allanridge Allanridge Allanridge Kameel. Klio. Klio. Klio. K1io. Klip. Klip. Klip. Klip. Klip. Klip. K1io.
wt.%
SiO, 53. Tl 54.41 51.16 51.05 52.50 52.'12 52.60 48.85 52.03 52.70 55.11 52.61 50.48 51.42 54.56
TIO, 1.12 1.21 1.40 2.54 0.54 0.:>5 0.62 0.42 0.40 0.48 0.66 0.57 0.57 0.63 0.82
A1,O) 13.69 13.51 14.94 10.21 12.75 13.62 14.39 9.98 9.62 11.20 14.34 12.74 13.12 13.89 13.54
Fe,O) 10.15 10.93 10.74 11.39 10.35 10.05 10.19 11.09 10.11 9.78 10.10 10.33 11.31 10.34 10.80
MoO 0.13 0.12 0.09 0.10 0.16 0.15 0.14 0.24 0.15 0.18 0.15 0.17 0.17 0.17 0.12
MRD J,6j 3.62 3.11 10.34 R.95 7,12 5,97 13.02 14.18 10.21 6.05 6.92 8.03 , 7.37 6.49
taO 6.76 7.15 5.88 CJ.U\} 7.74 8.69 9.00 10.13 7.28 8.54 7.22 12.03 8.54 9.87 5.87
No,O 4.0ó 3.27 3.72 0.02 2.73' 3.:!4 3.26 1.53 0.63 2.32 3.89 2.10 3.21 2.72 2 ..<;7
K,O 1.11 2.45 0.25 0.05 0.99 1.1)0 0.9'1 0.64 1.10 0.96 1.08 0.24 0.55 0.61 2.00
P,O! Q.24 0.16 0.27 0.44 0.08 0.08 0.10 0.06 0.05 0.07 0.09 0.08 0.08 0.08 0.11
H,O· 0.40 0.07 0.13 0.12 0.01 0.09 0.10 0.12 0.10 0.17 0.03 0.09 0.06 0.09 0.09
LOl 3.35 2.41 5.58 7.27 2.73 2.28 2.25 3.54 4.01 2.96 2.11 2.11 2.38 3.06 2.39
TOT· 97.75 99.41 97.27 99.62 99.53 99.'19 99.53 99.62 99.66 99.57 100.83 99.99 98.50 100.25 99.36
ppm
Rb 29.00 47.60 3.50 2.20 28.00 32.60 31.90 20.50 43.50 30.50 36.50 10.00 21.10 18.00 69.80
Ba 431.70 1,292.10 143.30 75.40 708.20 449.:l0 454.50 336.20 601.60 616.90 542.50 133.00 215.80 222.70 814.00
Sr 529.60 890.20 204.40 57.60 406.40 468.:l0 549.10 127.70 107.70 282.40 396.40 437.30 295.20 151.00 205.00
Zr 172.10 184.00 234.20 313. 70 61.90 64.70 74.90 53.90 45.70 59.90 77.00 63.30 67.30 73.70 100.30
Nb 9.10 10.70 11.00 16.40 3.20 3.00 4.3,0 3.30 0.50 3.50 2.70 4.60 3.70 4.00 4.80
Ni 154.00 118.90 112.70 80.40 202.30 163.20 138.40 381.60 391.70 286.00 130.40 196.00 203.20 199.70 166.60
Zo 97.00 9'7.50 92.20 87.60 74.30 75.40 80.20 73.20 70.40 65.40 72.10 74.90 80.40 76.00 83.40
Cr 56.80 36.80 28.30. 113.00 671.00 505.40 242.00 1,858.10 2,246.80 1,473.00 155.00 471.00 450.50 463.70 274.40
Cu 82.50 112.50 82.20 176.30 43.50 73.90 88.90 27.60 44.90 48.0'0 35.00 ' 76.20 54.90 71.00 77.90
V 171.40 165.60 182.20 273.00 192.10 Ig7.50 177.50 179.60 167.50 157.10 177.00 185.00 196.30 209.90 210.60
Y. 25.10 27.90 25.10 54.30 15.60 16.70 18.90 13.80 10.80 14.80 16.30 17.60 18.20 17.00 19.80
Sc 14.20 20.00 12.80 28.40 30.90 34.00 29.80 33.10 27.30 27.60 27.30 31.50 27.80 35.90 23.90
Co 42.60 47.30 50.50 53.20 50.20 44.50 48.10 61.20 56.90 50.30 47.00 50.40 53.40 48.80 50.20
CIPW Norms, (%)
Quartz 10.04 10.27 14.J:i 25.46 7.24 6.29 7.15 3.44 11.39 7.74 7.77 11.27 4.57 6.83 12.25
Corundum . - 0.10 - - . - - - -
Zircon 0.04 0.04 0.05 0.07 ' 0.01 0.01 0.02 0.01· 0.01 0.01 0.02 0.01 0.01 0.02 0.02
.-Ortheelase 6.99 14.96 1.62 0.32 6.06, 6.08 5.55 3.95 6.82 5.90 6.48 ' 1.45 3.39 3.72 12.23
A1bite 36.54 28.54 . 34.38 0.18 23.86 28.14 18.38 13.49 5.58 20.35 33.35 18.17 28.27 23.70 22.44
Anortbite 16.89 15.48' 25.50 29.69 20.30 20.21 22.61 19.26 21.13 17.97 18.75 25.20 20.59 24.62 20.17
>- Diopside 10.84 12.67 - 13.89 17A5 16.64 24.92 11.91 19.10 12.11 26.58 16.95 18.54 5.47
"'0 Wollastonite - - - . - - - -
"'0
('1) Hypersthene 4.60 3.46 8.46 27.92 16.61 iO.13 7.60 22.25 31.45 17.53 9.66 5.31 12.97 10.31 14.16
::I
Olivine . - - . - . - . .C- - - -x' Cbromite 0.01 0.01 0.01 0.03 0.15 0.11 0.05 0.42 0.51 0.33 0.03 0.10 0.10 0.10 0.06
w Haematite 10.80 11.28 11.73 12.35 10.69 10.~2 10.49 11.56 10.58 10.14 10.23 10.56 11.77 10.65 11.15
llmenite 0.34 0.30 0.25 0.25 0.32 .,Q.ll 0.32 ' 0.37 .r 0.11 0.27 0.35 0.37 0.38 0.37 0.28
N
N Spbene 2.49 2.69 3.21 - 0.96 0.99 1.15 0.59 0.88 0.88 l.i9 0.96 0.97 1.11 72o
Apatite 0.61 0.64 0.70 1.13 0.20 0.20 0.24 0.15 0.12 0.17 0.22 0.19 0.20 0.20 01..27 1
Rutile 0.09 2.62 - . - - . - - -
.. ;;i~
ERaJ-27 ER03-28 ER03-29 ER03-30 ER03-31 ER03-J2 ER03-33 S3-1 S3-2 S3-3 S3-4 S3-5 S3-6 S3-7 S3-13
Depth (metres) 1,456.32 1,556.90 1,597.85 1,675.00 1,717.18 1,753.40 1,823.00 274.85 317.05 351.90 382.90 429.60 472.90 500.50 765.10
Formalion Klip. Klip. Klip. Klip. Klip. xre. Klip. Allanridze Allanridge Allanridge Allanridge Allanridae Klip. Klip. Klio.
wl.%
SlO, 54.84 54.53 53.75 50.47 50.92 53.')4 53.21 47.93 51.77 51.31 53.14 53.32 55.14 55.00 52.64
TIO, o RR 0.91 0,93 1.10 LOR 1.0)6 1.01 1.16 1.15 1.14 1.06 1.16 1.18 1.26 1.53
A1,O) '14.44 14.29 14.09 15.06 14.85 13.73 14,07 14,18 13.52 13.37 13.24 13.53 13.49 13.79 14.46
Fe,O, 11.45 lUO 10.86 12.79 11.65 13.27 11.75 11.17 11.58 11.13 9.09 10.90 10.61 11.28 9.34
MnO 0.14 0.14 0.14 0.15 0.13 . 0.14 0.14 0.12 0.14 0.13 0.13 0.14 0.14 0.15 0.10
MgO 4.30 5.14 5.10 5.87 5.60 5.79 4.31 3.72 4.37 3.62 3.38 4.89 3.60 4.85 5.01
C.O 6.96 6.37 6.62 4.97 6.14 5.54 8.38 7.75 7.3i 8.19 10.03 6.47 6.95 4.77 6,17
N.,O 2.69 3.11 3.90 2.97 3.12 3.l0 2.13 2.87 3.84 3.80 5.06 4.19 3.35 3.27 0.18
K,O 217 1.62 2,05 1.96 1.92 0.49 1.96 1.32 1.59 1.58 0.22 1.86 2.09 2.33 2.38
P,Os 0.12 0.12 0.12 0.14 0.14 0.12 0.13 0.25 0.24 0.24 0.24 0.25 0.25 0.26 0.73
H,O- 0.01 0.02 0.04 0.03 0.02 O.)1 0.03 0.14 0.28 0.15 0.12 0.14 0.12 0.09 0.07
LOl 1.91 2.24 1.52 2.68 3.88 2.72 2.48 6.93 2.97 3.05 2.75 1.75 2.45 2.10 7.02
TOT 99.91 99.99 99.12 98.19 99.45 99.21 99.60 97.54 98.76 97.71 98.46 98.60 99.37 99.15 99.63
ppm
ab 84,50 62.20 70.60 71.50 66.00 16.50 62.10 25.70 32.30 32.50 5.80 35.80 38.10 42.70 79.30
B. 607.90 546.70 418.00 682.40 352.30 291.70 963.00 569.60 659.60 777.30 68.90 783. 70 898.60 1,907.20 786.30
Sr 305.90 251.80 143.10 184.20 182.60 199.10 519.70 254.50 664.80 692.30 734.30 403.50 826.80 426.50 77.10
Zr 109.90 107.20 111.90 121.80 117.90 116.20 104.20 192.70 173.40 175.90 161.90 185.80 183.90 206.70 355.40
Nb 6.40 6.50 5.90 6.40 5.80 7.80 7.60 8.60 9.60 9.50 8.90 9,60 10.00 10.70 15.70
Ni 105.20 124.70 120.00 145.20 135.60 138.70 133.60 176.50 168.70 157.60 118.10 163.20 113.50 107.60 78.90
Zo 96.10 89.40 82.20 108.70 91.90 104.80 90.20 108.30 106.40 109.00 60.40 99.90 102.00 106.20 83.10
Cr 18.30 44.60 27.60 60.80 53.60 86.70 67.00 51.40 52.20 45.60 41.60 52.10 39.90 26.80 194.30
Cu 123.10 79.80 85.80 133.40 108.30 92.80 108.10 76.60 90.00 78.60 63.50 103.50 108.90 119.90 8.80
V 207.90 206.40 217.40 240.70 231.40 244.20 196.90 197.60 188.10 172.20 187.70 189.80 163.70 173.80 220.30
y 21.70 20.10 21.10 23.10 23.10 23.20 22.30 26.50 27.30 27.00 32.80 25.90 26.90 27.60 39.10
Sc 25.30 28.90 23.10 27.00 26.70 22.00 19.50 20.00 20.90 14.70 18.30. 19.20 15.00 15.50 18.90
Co 52.00 51.60 49.90 64.70 52.00 65.80 58.00 56.60 55.50 51.70 35.60 51.00 46.40 46.60 29.50 !
CIPW Norms. (%)
Quartz 12.86 11.76 5,57 7.34 6.43 13.43 13.42 8.73 6.30 6.39 4.81 5.33 12.10 11.84 25.65
Corundum - - - - - - . - - - - - - - 2.21
Zircon 0,02 0.02 0.02 0,03 0.02 0.02 0.02 0.04 0.04 0.04 0.03 0.04 0.04 0.04 0.08
Ortheelase 13.12 9.82 12.45 12.16 11.90 3.01 11.96 8.63 9.85 9.89 1.36 11.38 12.78 14.22 15.23
Albite 23.23 26.92 33.82 26.32 27.63 28.94 18.56 26.84 34.02 34.02 44.79 36.66 29.28 28.53 1.65
Anorthite 21.37 20.75 15.27 23.06 21.83 22.00 23.78 24.25 15.70 15.65 13.37 13.08 16.16 16.68 28.18
;J> Diopside 8.45 6.56 11.74 4,62 2.06 12.19 10.03 13.67 17.61 19.02 11.90 11.47 2.18
--cc Wolluronire - - - - - - -
-
4.04 - - -
~ Hyperathene 7.02 10.06 7.58 15.31 12.46 13.99 5.42 5.60 5.08 1.40 - 7.09 3.97 11.46 13.48
:l
0- OU\ine - - - - - - - - - - - -
X Chromite - 0.01 0.01 0.01 0.01 0.02 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.05
Vol Haematite 11.68 11.77 11.13 13.40 12.19 13.75 12.10 12.35 12.12 11.78 9.51 11.27 10.96 11.63 10.09
Ilmenlte 0.34 0.35 0.35 0.38 0.33 0.35 0.3.5 0.34 0.37 0.34 0.33 0.36 0.35 0.37 0.23
N
N Sphene 1.76 1.84 1.89' 1.46 2.35 2:24 2.11 2.71 2.49 2.52 . 2.30 2.49 2.56 2.74 -
Apatile 0.29 0.29 0.29 0.35 0.35 0.30 0.3.2 0.66 0.60 0.61 0.60 0.62 0.62 0.65 1.88
Rutile - - 0.36 - - - - - - - 1.53--
r------------r------,-~----r_----~------_r------,_~.----_r----~;_------r_----_.------_.------._----~r------.------,-------
S3-14 S3-15 S3-16 S3-17 S3-18 S3-19 S3-20 S3-21 S3-22 S3-23 S3-25 S3-26 S3-27 S3-28 S3-29 '
i
Depth (metres) 780.70 799:80 881.9.0 897.9.0 1,081.70 1,1113.60 1,266.30 1,320.~0 1,450.?0 1,512.23 1,649.~0 1,681.10 1,746.90 1,792.60 1,861.251
Formation Klip. Klip. Makwassie' Makwassie Klip. _ Klip. Klip. Klip. Klip. Klip. Klip. Klij>. Klip. Klip. Klip.
wt.%
SiO,' 50.02 53.58 56.67 54.27 52.42 50.-10 53.70 53.84 52.20 53.31 52.39 52.07 53.00 53.90 53.89 !
TIO, I'IJ 1.57. ur, I 7.') o.ss (UR 0,6.6 0.52 0.57 0.55 0.65 O.RI 1.00 0.92 0.92
Al,O, ')3.62 I4.2M 14.13 13.'.13 11.94 9.:16 13.98 11.89 li42 11.96 13.07 13.26 14.51 14.31 14.07
Fe,O, 7.82 7.77 8.60 8.63 10:06 10.0;<1 10.06 10.13 10.27 10.36 11.19 10.81 11.97 11.43 11.60
.MnO 0.10 0.10 0.11 0.10 0.16 0.15 0.14 0.16 0.15 0.16 0.16 0.16 0.18 0.15 0.14,
MgO 3.54 3.88 3.56 2.42 9.55 13.·10 5.57 6.92 6.56 7.80 6.33 6.69 4.74 3.95 4.18 !
CoO' 9.75 6.71 5.00 7.41 7.61 7.18 7.94 8.27 9.14 9.36 9.91 7.66 5.74 8.31 7.82
Na,O 0.79 2.26 3.75 3.34 2.60 1.1)7 3.84 3.13 2.47 3.14 2.04 3.38 3.30 3.59 2.96
K,O 2.36 U4 0.19 1.27 1.03 .0.64 0.91 0.55 1.50 0.82 1.57 1.30 2.11 0.87 1.03 I
P,O, 0.68 0.70 0.55 0.55 0.08 0.')5 0.10 0.07 0.07 0.06 0.09· 0.11 0.13 0.12 0.12
H,O- 0.08 0.05 0.02 0.14 0.')7 0.06 0.04 0.05 0.02 0.02 0.10 0.04 0.06 0.11
LOl 9.23 6,42 4.40 4.89 2.78 3.'77 2.47 2.29 2.01 2.11 1.72 2.45 2.12 1.68 1.87
TOT 99.42 98.76 98.37 98.12 98.93 97.051 99.43 97.81 97.41 99.65 99.14 98.80 98.84 99.29 98.71
ppm
Rb 86.60 56.80 5.40 30.90 23.80 28.:30 25.40 18.60 60.10 26.80 55.40 43.00 73.00 34.90 41.40
Ba 811.50 631.70 206.40 1,507.40 475.90 278.10 243.40 293.60 425.50 211.60 657.90' 377.10 94).20 342.20 391.20
Sr 151.10 212.90 704.40 766.50 175.40 118.50 399.30 303.00 275.00 105.00 379.20 161.60 18i.~0 400.80 449.90
Zi 333.00 342.60 345.70 329.40 70.40 52.30 83.90 61.20 67.20 63.00 68.90 98.80 . 117.00 105.30 102.80
Nb 17.20 16.40 16.40 17.20 2.70 1.70' 3.90 2.50 3.20 2.80 4.70 4.70 ' 6.50 6.40 7.60
Ni 67.70 72.50 97.90 82.00 243.30 362.10 126.20 198.50 203.70 217.00 177.70 189.60 110.70 105.20 120.20
Zn 106.70 101.20 100.50 103.80 68.40 69.50 66.60 70.40 72.00 74.60 82.60 88.60 74.20 89.10 91.60
Cr 168.40 202.70 363.90 325.70 997.60 2,054.')0 151.70 526.10 496.80 50·Ó.80 388.80 346.30 22.80 25.60 33.40
Cu 30.00 13.liO 11.60 36.50 32.90 51.50 96.90 48.70 73.70 71.90 86.60 87.10 44.80 108.90 88.40
V 195.20 217.10 194.20 176.90 188.40 174.10 160.40 186.60 191.60 205.00 202.40 193.70 217.60 207.40 215.50
Y 44.90 43.30 40.70 41.40 15.00 12.10 17.10 14.60 15.30 13.90 17.60 19.20 21.20 21.40 21.70
Sc 24.50 18.60 19.50 19.50 28.70 27.60 31.70 27.30 32.30 28.90 32.90 27.30 25.60 23.90 29.80
Co 24.90 24.30 29.40 30.60 49.90 58.30 44.70 46.70 50.10 50.20 51.40 53.50 53.30 52.00 52.50
CIPW Norms. (%)
Quartz 17.52 18.67 20.86 15.99 7.48 10.38 7.46 11.30 9.02 7.00 10.06 5.88 8.91 10.88 13.92
Corundum - - - - - - - - - - - -
Zircon 0.07 0.07 0.07 0.07 0.01 0.01 0.02 0.01 .0.01 0.01 0.01 0.02 0.02 0.02 0.02
Ortheelase 15.52 9.88 1.20. 8.07 6.35 4.05 5.56 3.41 9.32 4.98 9.55 8.00 12.93 5.28 6.31 I
Albite 7.42 20.71' 33.78 30.32 22.91 9.65 33.53 27.74 21.92 27.24 17.72 29.71 28.88 31.14 25.89
Anorthite 29.60 .. '26:32 22.58 20.75 18.64 21.57 18.82 17.58 19.28 16.53 22.48 17.85 19.23 20.90 22.84 '
;l> Diopside 11.18 - 8.66 14.68 11.71 15.27 18.57 20.67 22.93 20.29 14.64 5.36 14.17 10.96
"0
"0 Wollastonite - - - - - - - - --
:C:ls> Hypersthene 4.61 10.46 9'.44 2.47 17.98 30.16 7.24 9.45 7.56 9.29 6.80 10.53 9.73 3.52 5.691
x0-' OIivine - - - - - - - - - - - - - -Chromite 0.04 0.05 0.08 0.08 0.22 . 0.47 0.03 0.12 0.11 0.11 0.09 0.08 0.01 0.01 0.01
W Haematite 8.68 8.41 9.16 9.26 10.48 11.35 10.38 10.61 10.77 10.62 11.49 11.23 12.38 11.72 11.99
tv lImenite 0.24 0.23 0.2'3 0.21 0.28 O.._!4 0.33 0.34 0.33 0.35 0.35 0.37 0.44 0.37 0.35 I
tv Sphene 3.60 3.55 0.24 3.14 1.04 0•8. 2 1.24 0.89 1.04 0.94 1.18 1.59 1.98 1.84 1.88
tv Apatite 1.79 1.80 1.40 1.41 0.21 0.\13 0.25 0.17 0.17· 0.15 0.22 0.27 0.32 0.29 0.29
Rutile 0.08 1.23 - - - - -_ _ - _ _ _-_ ___ -_ _ -____ - -
,!.,.
\
S3-30 S3-31 S3-32 S3-33 S5-t S5··2 S5-3 S5-4 SS-IS S5-17 S5-19 -, S5-20 S5-21· \ S5-22 S5-23
'.
Depth <.metres) 1.921.25 1,981.60 2,021.90 2,078.85 33~:00 361.:'5 38~.89 414.60 952.70 980.4.0 1,046.15 1,124.78 1,183.85 1,233.85 1,289.90 I
FormaIIon Klip. Klip. Klip. Klip. AUanndge AUanndge Allanridge Allanridge MakwassIe MakwassIe Klip. Klip. Klip. Klip. Klip.
wt.%
SiO, 54.56 52.92 52.80 53.63 54.68 53.70 52.38 53.21 54.96 59.64 56.01 53.36 57.79 49.67 52.92
TlO, 0.91 0.97 1.01 1.00 1.15 1.::0 0.98 1.21 1.24 ).28 0.57 0.63 0.48 0.39 0.49
AI,O, 13.91 14.18 14.10 14.12 13.81· IB7 13.74 14.22 13.52 13.99 12.19 14.05 9.12 9.33 11.79
Fe,O, 11.50 12.Q8 11.86 12.35 10.57 11.03 11.89 11.40 10.79 7.96 10.18 10.59 9.26 10.48 9.93
MoO 0.16 0.15 0.15 0.14 0.13 0.:3 0.16 0.13 0.14 0.08 0.17 0.13 0.18 0.16 0.16
MgO 4.15 4.72 4.45 4.51 3.85 4.55 4.60 4.65 3.53 4.08 6.60 6.33 9.74 15.81 9.80
CoO 8.76 7.83 7.84 7.56 6.43 6.81 6.63 6.83 6.33 3.75 6.61 6.48 7.17 6.97 7.65
Na,O 3.36 3.05 3.14 2.62 4.08 3.98 4.63 3.75 2.36 3.19 3.79' 2.71 1.75 0.86 2.84
x.o 0.42 1.26 1.00 0.87 0.47 1.43 0.28 1.49 1.76 0.80 0.75 1:06 0.41 0.52 0.30
P,O, 0.12 0.13 0.1j 0.13 0.24 0.~6 0.22 0.26 0.26 0.46 0.08 0.10 0.05 0.06 0.07
11,0- 0.11 0.1.5 0.09 0.04 0.10 0.IJ8 0.22 0.09 0.07 0.08 0.12 0.17 0.14 0.20 0.18
LOl 1.87 ". 2.'03 2.27 2.29 3.20 2.00 1.99 1.95 3.22 3.75 1.79 2.81 2.94 4.70 2.55
TOT 99.83 99.47 98.84 99.26 98.71 99.14 97.72 99. i9 98.18 99.06 98.86 98.42 99.03 99.15 98.68
ppm
Rb 16.70 51.50 37.70 30.80 9.50 25.20 3.40 26.30 30.80 36.10 22.10 35.90 8.70 17.60 9.00
Ba 155.40 475.20 367.80 467.70 199.10 491.'70 99.10 571.40 695.40 391.00 330.90 477.70 84.50 196.40 124.50
Sr 351.60 402.00 412.10 307.00 599.00 476.70 307.80 570.40 737.00 384.50 306.10 381.20 54.80 117.30 343.40
Zr 101.00 104.90 106.50 109.60 169.10 189.20 170.80 183.00 306.10 518.80 71.90 79.30 63.20 48.50 58.70
Nb 5.20 7.90 7.70 7.00 7.50 9.40 8.10 8.00 17.10 22.90 4.20 3.80 1.30 1.80 2.50
NI 122.00 139.10 135.10 131.20 146.80 162.50 170.90 164.40 100.90 53.90 165.20 151.00 282.20 470.60 276.90
Zo 84.60 96.90 91.70 91.80 96.20 103:1!) 96.10 106.30 97.00 92.50 64.20 86.20 61.00 75.20 69.10
Cr 32.00 58.80 61.90 79.40 45.80 58.50 54.30 66.70 397.7.0 229.80 572.10 320.00 1,573.10 2.760.60 1,381.60
Cu 91.60 113.20 106.40 95.80 123.00 10UO 89.80 114.20 28.10 6.40 27.50 56.50 26.30 33.00 76.10
V 202.20 216.50 222.00 219.80 188.10 185.60 174.80 185.00 173.80 142.80 195.20 194.50 166.60 168.90 158.90
Y 18.40 22.50 21.40 22.10 26.20 26:30 21.50 26.50 43.30 51.00 15.40 17.20 10.80 I 11.40 14.10
Sc 26.20 25.30 32.60 27.60 20.90 20.60 15.00 20.30 22.80 11.10 29.20 25.30 29.80 34.30 32.30
Co 53.70 57.30 57.00 57.80 47.60 53.80 61.70 53.00 35.20 23.20 44.40 48.40 46.50 65.30 52.80
CIPW Norms. (%)
Quartz 13.58 10.74 11.58 15.62 13.53 8.u7 7.60 8.17 19.13 26.33 11.56 12.85 21.35 7.82 8.87
Corundum - - . - - . - . - - - 2.19 - - --
Zircon 0.02 0.02 0.02 0.02 0.04' 0:)4 0.04 0.04 0.06 0.11 0.01 0.02 0.01 0.01 o.oi
Ortboelase 2.54 7.67 6.14 5.32 2.92 8.72 I.73 9.08 10.98 4.98 4.58 6.58 2.53 3.27 1.85
Albite 29.05 26.52 27.54 22.87 36.18 34.69 41.02 32.66 21.04 28.34 33.08 24.02 15.43 7.72 25.04
Anorthite 22.13 2i.90 22.23 25.00 18.88 16.55 16.65 18.12 22.30 16.64 14.49 24.18 16.49 21.30 19.34
~ Diopside 14.9)- 11.41 11.29 7.87 7.49 10.23 10.60 9.08 4.26 - 13.69 5.72 14.79 10.74 14.45
"0
"0 WollastoDÏle -. - - - - - - - - -~ Hyperathene 3.66 6.80 6.26 7.94' 6.58 6.94 7.08 1.72 7.30 10.67 10.62 13.87 18.42 36.80 18.74
::l
xC-' Olivine - - - - - - - - - - -...., Cbromite 0.01 0.01 0.01 0.02 0.01 0.01 0.01 0.01. 0.09 0.05 0.13 0.07 0.35 0.63 0.31
Haematite n.75 12:42 12.29 12.74 11.08 11.36 12.45 11.73 11.37 8.36 10.50 11.10 9.65 11.12 10.35
N Ilmenite 0.39 0.37 0.37 0.35 0.34 0.33 0.41 . 0.33 0.29 0.16 0.34 0.30 0.25 0.08 0.24.N..., Sphene 1.78 1.97 .2.09 2.09 2.53 2.'61 1.99 2.63 2.84 - .1.00 1.24 0.90 0.91 0.95
Apatite 0.29 0.32 0.32 0.32 0.60 9.64 0.55 0.64 0.65 1.15 0.20 0.25 0.12 0.15 0.17
Rutile _-_ _ - - - - - - 1.26 - - -
S5-24 S5-25 S5-26 S5-27 S5-28 S5~.29 S5-30 S5-31 S5-32 S5-33 DKL6-1 DKL6-2 DKL6-3 DKL6-4 DKL6-5
Depth (metres) 1,351.90 1,421.07. 1,471.55 1,498.30 1,575.95 1,630.30 1,709.70 1,870.40 1,919.95 1,976.80 282.70 325.00 350.30 391.00 416.65
Formniion Klip. Klip. Klip. Klip. Klip. _. Klip. Klip. Klip. Klip. Klip. Allanridge Allanridge Allanridge Allanridge Allanridge
wl,%
SiO, 52.72 52.?7 52.91 5U7 52.56 50.76 52.04 54.70 55.75 53.88 53.50 52.40 53.35 : 53.52 55.81
TiO, 0.49' 0.58 0.75 0.63 0.68 051 0.54 0.93 0.89 0.91 1.22 1.15 1.16 \ 1.18 1.21
Al,O) ,11.72 13..03 14.22 12.74 13.30 12.57 11.06 14.21 13.95 13.78 14.09 14.21 14.20 13.94 13.61
Fe,Ol 9.95 10.78 11.07 11.06 10.81 10.50 10.88 11.77 11.20 11.71 10.22 11.58 11.96 11.53 10.35
MnO 0.15 0.15 0.14 0.16 0.16 0.15 0.16 0.16 0.12 0.15 0.11 0.14 0.14 0.14 0.14
MgD 10.14 7.36 5.54 7.43 7.24 7.92 9.14 4.10 4:48 4.81 3.80 4.77 5.34 4.50 4.31
CaD 8.44 9.78 7.57 8.78 8.01 9.53 9.96 7.59 5.56 6.57 7.17 6.88 4.96 6.81 6.86
Na,O 1.18 2.28 3.03 3.31 3.00 2.79 1.70 3.33 3.41 2.61 4.06 4.61 3.41 3.68 3.16
K,D 1.83 0.85 1.63 0.78 0.90 0.39 1.03 0.75 1.32 2.03 1.17 0.16 1.35 1.73 2.42
P,O, 0.07 0.08 0.09 0.07 0.08 0.a7 0.07 0.12 0.12 0.12 0.26 0.24 0.24 0.25 0.26
H,O- 0.04 0.12 0.05 0.10 0.12 0.14 0.09 0.15 0.14 0.07 0.40 0.11 0.16 0.10 0.22
LOl 2.77 2.29 2.05 2.14 2.07 2.60 2.15 1.81 2.38 2.55 3.35 2.37 2.55 . 2.02 2.64
TOT 99.50 100.17 99.05 98.97 98.93 98.03 98.82 99.62 99.32 99.19 99.35 98.62 98.82 99.40 100.99 I
ppm
Rb 120~20 29.50 59.20 30.80 34.90 n.70 46.70 29.60 47.30 76.20 27.60 3.90 22.90 34.20 46.90 I
Ba 345.10 345.30 656.70 307.50 394.70 98.20 347.70 87.50 525.00 582.90 510.20 69.80 650.40 1,016.20 1,495.70
Sr 125.50 338.10 364.20 284.00 298.90 126.70 261.10 536.30 249.80 223.10 864.60 307.90 398.70 769.70 834.70
Zr 71.30 67.60 86.00 71.70 74.20 60.90 58.10 99.70 105.20 107.00 177.40 182.50 175.40 180.80 194.60
Nb 3.80 5.10 4.70 5.10 4.60 3.60 4.90 6.40 4.90 6.50 9.30 8.70 8.00 11.00 10.90
Nl 276.70 207.40 149.60 209.20 194.50 241.00 294.00 105.30 108.10 113.30 155.30 164.70 180.00 167.80 106.40
Zo 71:10 81.40 85.90 81.50 82.40 77.30 81.30 88.00 84.40 93.40 81.70 106.20 126.70 113.00 97.40
Cr 1,257.60 527.60 243.40 481.10 444.30 610.20 893.00 21.70 29.60 36.80 54.60 57.00 74.60 62.40 30.20
Cu 58.80 59.40 98.10 61.50 76.30 64.00 62.30 102.20 60.70 73.10 40.10 221.70 88.20 118.40 125.00
V 157.60 185.60 184.80 198.10 205.80 194.10 190.20 213.80 197.00 204.10 187.40 167.40 190.70 184.10 159.40
y 14.70 18.30 20.10 18.50 17.20 15.10 17.10 21.30 19.50 20.40 27.60 23.20 24.50 I 29.60 29.50
Sc 26.70 27.80 20.60 34.30 33.40 41.50 31.20 26.70 27.60 22.00 21.70 15.30 23.10 I 18.90 13.90
Co 51.30 53.00 55.50 52.40 53.70 55.10 57.40 52.00 48.20 52.20 46.30 64.10 )9.20 ' 52.40 43.50
CIPW Norms, (%)
Quartz 10.49 10.27 8.59 5.48 8.27 6.91 10.10 13.99 1(74 12.98 9.11 7.27 11.59 8.41 11.41
Corundum . - - - - '.- - - - . - -
Zircon 0.01 0.01 0.02 0.01 0.02 0.01 0.01 0.02 0.02 0.02 0.04 0.04 0.04 0.04 0.04
Ortheelase 11.23 5.15 9.96 4.78 5.51 2.42 6.32 4.55 8.08 12.45 7.24 0.99 8.31 10.52 14.59
Albite 10.33 19.73 26.44 28.95 26.24 24.77 14.89 28.85 29.81 22.87 35.93 40.57 30.02 32.01 27.25
Anorthlte 22.00 23.35 21.06 18.21 20.87 21.94 20.21 22.15 19.51 20.62 17.58 18.33 20.30 16.92 16.17
:> Diopside 15.28 19.07 11.92 19.40 14.09 20.25· 22.82 10.29 4.49 7.76 11.23 9.48 0.35 10.22 10.77
"0
"0 WollaSlonile - - - - - - - - - - - - -
(1) Hyperstaene 19.04 9.92 8.72 10.14 12.12 11.32 13.00 5.69 9.45 8.81 4.71 7.96 13.68 6.80 5.97
;:l
c.. Olivine - - - - - - - - - - - -
>< Chromite 0.28 0.12 0.05 0.11 0.10 0.14 0.20 - 0.01 0.01 0.01 0.01 0.02 0.01 0.01
w Haematite 10.29 11.03 11.42 11.43 n.17 11.02 11.27 12.05 11.57 12.13 10.69 12.04 12.44 11.85 10.55
IV Ilmenite 0.23 0.32 0.33 0.35 0.35 0.32 0.31 0.38 0.30 0.37 0.29 0.36 0.36 0.36 0.34
IV Sphene 0.95 1.05 1.48 1.15 1.27 -moo 0.97 1.85 1.87 1.84 2.76 2.47 2.50 2.53 2.60
.j:o.
. Apatite 0.17 0.19 0.22 0.17 0.20 0.17 0.17 0.29 0.30 0.30 0.65 0.59 0.60 0.61 0.64
Ruti1e - - - - - - - - - - - - - -
------
OHI-I OHI-2 OHI-3 OHI-4 OHI-5 OHI··6 OHI-7 OHI-8 OHI-9 OHI-IO OHl-11 OHI-12 OHI-13 OHI-14 OHI-15
Depth (metres) 56.50 65.10 75.00 83.80 125.50 14J.:10 160.40 164.70 167.20 169.20 175.30 189.00 212.00 223.70 248.30
Formation Allanridge Allanridge Allanridge Allanridge Allanridge Allanridge Allanridae Allanridae Allanridge Allanridge Allanridge Allanridge Allanridge Allanridge Allanridge
wt.%
SiO, 56.83 52.00 55.58 53.41 56.94 5S.:l7 55.01 58.17 53.67 60.13 56.92 58.29 56.97 54.36 51.21
TlO, 0.7fi 0.94 o.n O.RO 0.87 0."6 0.72 0.73 0.73 0.75 0.72 0.76 0.66 0.89 1.01
Al,O) 12.99 15.77 13.17 13.57 13.44 13.12 13.77 13.03 15.89 13.43 13.56 13.58 12.67 12.72 13.22
Fe,O) 8.11 9.13 8.55 9.98 9.89 9.95 9.09 7.68 8.91 6.61 7.89 8.41 7.85 9.98 10.43
MnO 0.08 0.13 0.12 0.14 0.12 0.12 0.12 0.11 0.09 0.08 0.13 0.09 0.10 0.14 0.13
MgO 3.21 4.28 4.54 4.94 4.27 4.15 5.33 4.77 3.78 4.31 4.82 3.66 3.87 4.66 3.32
<:;00 4.95 6.58 6.69 6.21 6.71 6.,;9 4.80 4.56 6.25 4.21 5.93 6.24 6.36 6.88 7.95
NOlO 2.48 3.61 3.98 3.64 3.47 3.33 3.79 4.51 4.17 4.79 4.65 3.60 3.03 . 3.34 3.31
K,O 2.54 0.23 0.64 0.95 1.45 1.96 1.20 0.67 0.19 1.11 0.42 1.76 1.65 1.64 0.84
P,O, 0.15 0.17 0.15 0.15 0.16 0.16 0.15 0.15 0.16 0.16 0.15 0.13 0.14 0.20 0.20
H,O- 0.14 0.31 0.56 0.34 0.14 0.12 0.32 0.34 0.18 0.15 0.20 0.24 0.23 0.13 0.34
LOl 4.34 5.18 2.57 2.98 2.68 2.23 2.61 2.26 3.29 2.35 2.11 2.59 4.10 2.67 5.15
TOT 96.58 98.33 97.33 97.11 100.14 98A6 96.91 96.98 97.31 98.08 97.50 99.35 97.63 97.61 97.11
ppm
Rb 59.50 8.00 15.40 21.30 38.50 60:30 28.70 17.30 5.80 25.60 11.10 45.10 41.00 46.60 23.90
Ba 517.30 88.70 203.40 277.00 345.80 401.40 363.80 258.70 91.20 369.00 127.60 637.00 672.10 503.80 316.50
Sr 339.20 604.50 404.90 176.60 299.70 343.,70 161.30 218.70 867.70 171.90 411.20 270.80 348.10 294.10 487.10
Zr 134.10 142.10 135.00 144.20 146.90 139.80 160.30 155.60 133.20 163.00 148.60 154.60 139.60 164.10 175.30
Nb 5.50 6.60 6.10 5.80 6.60 7.00 4.70 3.00 4.20 3.20 4.10 4.50 4.40 7.60 8.00
Ni 79.50 92.90 90.60 104.30 94.60 92.50 129.60 114.60 108.30 110.40 107.00 114.50 116.60 121.50 99.80
Zo 68.20 76.30 68.90 76.70 90.20 84.60 82.10 68.50 73.40 62.20 67.50 70.00 68.90 84.30 87.40
Cr 176.10 135.40 166.60 147.40 118.60 123.30 198.60 . 194.50 177.80 195.80 192.90 193.20 194.70 262.10 85.20
Cu 135.60 7.80 125.30 108.30 89.10 86.20 46.50 112.60 29.70 23.10 52.90 56.30 57.20 94.30 79.60
V 165.70 212.50 203.90 182.70 169.90 167.30 160.80 . 151.60 203.60 128.80 177.60 149.20 145.80 180.70 171.80
'y 15.90 20.40 20.10 18.70 21.10 20.30 17.30 15.30 17.10 12.60 17.40 16.90 15.90 22.00 25.20
Se 18.10 2HO 28.70 10.80 21.40 16.40 18.60 17.50. 21.40 16.90 18.10 20.00 18.60 18.10 10.00
Co 29.70 38.20 34.30 47.10 44.50 42.90 42.90 31.30 33.00 28.80 33.00 37.80 29.30 44.50 46.60
CIPW Norms. (%)
Quartz 20.75 12.09 13.50 11.62 14.58 f3.06 12.53 15.54 12.05 15.38 12.27 15.75 18.33 11.97 12.49
Corundum - - - - - - - - -
Zircon 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.04
Ortheelase 16.32 1.47 4.02 6.00 8.82 12 08 7.56 4.20 1.20 . 6.87 2.61 10.80 10.47 10.24 5.43
A1bite 22.78 32.90 35.75 32.84 30.17 2932 34.12 40.43 37.60 42.40 41.33 31.56 27.48 29.81 30.57
Anortbite 18.29 28.20 17.20 19.09 17.30 1569 18.13 14.15 25.71 12.44 15.66 16.29 17.29 15.71 20.47
:> Diopside 3.95 2.40 11.56 8.19 10.47 1228 3.26 5.24 3.33 4.75' 9.60 9.99 10.79 12.84 14.18
"0
"0 Wollastonite - - - - - - - - - - - -
('!> Hypersfbene 6.85 10.37 6.65 9.-33 6.08 507 12.61 10.16 8.49 9.03 8.17 4.82 5.34 6.30 2.46:::l
Q. OJivine - - - ..x' - - - - - -Chromite 0.04 0.03 0.04 0.03 0.03 0.03 0.05 0.04 0.04 0.04 0.04 0.04 0.04 0.06 0.02
W Haematite 8.81 9.83 9.08 10.64 10.16 10.35 9.67 8.14 9.49. 6.92 8.29 8.71 8.41 10.53 11.38
I1menite 0.19 0.31 0.28 0.34 0.28 0~28 0.29 0.26 0.22 0.19 0.30 0.21 0.24 0.32 0.33lV
lV Sphéne 1.79 2.08 1.67 1.66 1.83 t:58 1.51 1.57 1.63 1.69 1.47 1.66 1.43 1.89 2.28
<Jl
Apatite 0.39 0.44 0.38 0.38 0.39 0.40 0.38 0.38 0.41 0.40 0.37 0.32 0.36 0.50 0.52
Rtitile - - - _:___ - - - - - - -
. ,
.. J .
DHI-16 DHI-17 DHI-18 DHI-19 DHI-20 DHI-:!! DHI-22 DHI-23 DHI-24 DHi-25 DHI-26 DHI-28 DHI-29 DHI-30 DHI-31
Depth (metres) 262.90 285.00 309.60 340.00 367.20 382.00 . 399.80 411.40 420.80 431.40 441.70 475.70 496.00 513.50 525.10
Formation Allanridge Allanridge Allanridge Allanridge' Allanridge Allanridge Allanridge Allanridge Allanridge Allanridge Allanridge Allanridge Allanridge Allanridge Allanridge
wt.%
SiO, 52.68 53.92 54.50 53.83 55.00 54.91 54.04 50.20 52.89 52.00 52.47 53.56 49.54 51.21 51.34
TlO, 0.99 1.03 0.95 0.96 0.92 1.04 1.01 1.13 1.03 0.97 1.01 0.95 1.03 1.08 1.03
Al,O, ·12.~K IJ.05 IJ.I'! 12.7'! 12.47 12.94 12.92 13.63 IJ.33 13.15 13.28 12.75 12.78 13.21 12.61
Fe,OJ 10.66 10.82 10.56 11.24 10.84 11.33 10.89 10.28 10.73 10.35 10.44 10.35 11.63 11.27 6:39
MnO 0.12 0.13 0.13 0.15 0.14 0.15 0.13 0.14 0.15 0.14 0.13 0.13 0.13 0.13 0.11
M~O 3.40 2.93 3.62 4.00 4.27 4.08 3.62 4.85 3.67 4.57 4.20 4.54 3.61 4.00 2.88
CaO 6.3.8 6.76 6.66 6.64 6.92 6.·)2 6.71 6.02 7.09 7.88 8.19 7.50 7.95 7.71 10.13
Na,O 2.91 3.41 3.44 3.73 3.50 BI 3.31 2.54 3.41 4.11 3.49 3.38 2.97 3.73 3.97
K,O 2.48 1.16 1.45 0.79 1.72 lAS 2.13 0.86 1.31 0.15 0.77 1.59 2.38 1.74 1.49
.~
P,O, 0.21 0.23 0.21 0.21 0.21 0.23 0.23 0.23 0.24 0.23 0.23 0.23 0.23 0.24 0.23
H,O- 0.24 0.17 0.15 0.17 0.18 022 0.13 0.14 0.08 0.15 0.14 0.05 0.20 0.17 0.16
LOl 4.12 3.80 3.03 2.91 2.14 2.-)1 2.95 6.39 3.36 4.10 4.68 2.89 4.70 3.64 6.84
TOT 97.17 97.41 97.89 97.42 98.31 98.29 98.07 96.41 97.29 97.80 99.03 97.92 97.15 98.13 97.18
ppm
Rb 68.40 30.00 36.90 18.10 39.70 33.10 49.70 19.70 28.10 4.50 14.50 31.90 52.90 37.90 29.80
Ba 935.10 444.30 379.30 378.50 510.80 493.1.0 957.10 885.10 579.60 49.20 466.30 492.30 1,209.70 1,090.50 469.10
Sr 302.90 579.90 399.20 368.50 4)8.20 449.50 422.30 367.50 423.70 506.90 442.00 453.~0 613.70 635.20 478.00
Zr 188.90 198.10 183.30 177.00 169.40 190.70 188.10 195.90 184.90 176.00 169.90 183.60 173.70 177.50 176.20
Nb 10.40 9.80 9.50 8.30 7.60 9.90 10.60 8.20 8.40 7.80 6.00 9.00 9.70 9.80 8.10
Ni 99.80 100.50 109.60 135.00 144.50 124.70 123.70 131.80 125.60 161.90 167.20 177.10 164.00 150.80 146.50
Zo 97.00 90.30 98.50 91.70 97.00 94.00 100.30 120.90 82.10 89.20 83.20 100.40 111.70 103.50 76.00
Cr 73.90 30.30 33.60 74.00 86.80 45.90 33.50 32.40 30.40 148.50 188.40 191.20 62.50 53.90 68.40
Cu 107.10 140.90 94.00 103.00 87.10 66.30 106.40 19.70 102.10 43.00 184.50 93.10 108.80 113.50 45.20
V 164.90 178.50 177.70 175.50 175.10 183.80 173.00 196.90 178.00 162.60 173.10 161.20 167.20 185.20 160.90
Y 25.60 27.70 25.30 23.50 23.30 24.90 12.50 . 26.70 . 24.50 25.30 23.90 27.30 26.50 26.80 24.70
Sc 14.40 13.60 16.70 19.20 19.20 23.40 16.90 20.30 16.90 15.00 20.00 16.90 18.30 16.10 25.30
Co 47.00 46.90 47.40 54.60 51.00 50.80 48.70 48.90 48.00 45.00 49.30 44.80 51.90 52.70 29.20
CIPW Norms. (%)
Quartz 12.20' 15.66 13.86 13.63 12.13 11.90 11.83 15.22 12.28 9.48 11.14 10.57 6.86 6.15 5.57
Corundum - - - - - - - - - - - -
Zircon 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04
Orthoclase 15.82 7.35 '9.06 4.96 10.61 8.93 13.27 5.66 8.26 0.95 4.84 9.91 1\5.27 10.92 9.78
\
Albite 26.53 30.88 30.73 33.45 30.85 34.44 29.48 23.91 30.74 . 37.17 31.34 30.11 27:24 33.46 37.25
Anorthite 16.23 18.09 17.20 16.80 13.81 14.05 14.88 25.94 18.36 18.18 19.45 15.73 15.77 . , 15.06 13.53
:> Diopside 10.62 10.37 10.60 10.96 14.12 9.89 12.40 1.83 11.42 14.99 14.99 15.02 17.69 16.38 17.18
"0 Wollastonite - - - - - - - - - - - - 6.43"0
Cl> Hyperathene 4.2:2 ~:Ol . 4.61 5.49 4.54 6 Ol 3.76 12.60 4.46 5.22 4.16 4.96 1.58 2.99
:::I
C- Olivlne - - - - - - - - - - - -
X Chromite 0.02 0.01 0.01 0.02 0.02 0.01 0.01 0.01 0.01 0.03 0.04 0.04 0.01 0.01 0.02
W Haematite 11.49 11.58 11.15 11.91 11.29 P.79 11.46 11.44 11.43 11.06 11.08 10.90 12.61 11.95 7.09
N IImenlte 0.30 0.33 0.33 0.38 0.35
O~37.
...... -« ~ .0.33 0.38 0.38 0.35 0.32 0.32 0.35 0.34 0.30
N Sphene 2.23 2.28 2.04 2.01 1.90 2,1·8 2.19 2.60 2.20 2.09 2.21 2.04 2.29 2.38 2.42
0\
Apatite 0.54 0.59 0.53 0.53 0.52 0.57 0.58 0.61 0.61 0.58 0.58 0.58 0.60 0.61 0.61
Rutile - - -- -__ - - - - - - - - - - - -
~t
:.J(
~-----------r------.-------r------.-------r----~'------'-.-------r------.-----~r------.------.-------.------,-------,-------
OHI-32 OBI-33 OHI-34 OHI-35 OHI,36 DIH-;;? OHI-38 OHI-39 OHI-40 LRP3-3 LRP3-4 LRP3-?' LRP3-8 LRP3-9 LRP3-10
Depth (metres) 532.00 537.60 542.50 551.30 560.40 575.'0 583.20 598.30 632.50 535.54 541.12 554.62 567.65 575.40 579.60
Fornintlon Allanridge Allanridge Allanridge Allanridge Allanridge Allanrid/!e Allanridge Allanridge Allanridge Klip. Klip. Klip. Klip. Klip. Klip.
wt.%
SiO, 44.25 56.03 48.38 48.87 52.89 52.:;3 51.7-7 52.51 52.99 58.35 43.79 57.26 57.14 51.18 51.81
TiO, 1.06 1.01 1.04 1.17 1.05 1.09 1.07 1.06 I.Ó8 1.50 1.35 1.56 0.50 0.45 0.46
AI,OJ 13.60 12.30 13.13 lUK 13.20 13.;;8 13.48 13.37 13.50 14.40 13.96 14.84 11.63 12.03 11.19
Fe,03 4.51 8.29 11.96 8.27 11.62 10':;2 9.51 11.01 11.17 9.44 11.61 11.70 9.46 9.40 10.66
MoO 0.15 0.13 0.16 0.14 0.12 0.::3 0.13 0.13 0.14 0.09 0.11 0.10 0.13 0.16 0.19
MgO 1.86 4.45 4.18 3.49 3.94 3.:15 3.87 4.21 4.27 4.27 5.55 5.84 10.98 11.77 12.29
CaO 13.51 6.83 6.93 10.15 5.70 6.'15 7.34 6.93 7.09 4.27 10.88 2.86 3.48 5.80 6.55
Na,O 3.80 4.31 2.50 3.06 3.62 4.07 3.85 3.13 4.05 0.12 0.35 0.55 0.85 1.33 1.28
K,O 2.40 0.90 0.2'1 0.64 1.01 1.':6 1.02 1.89 0.84 2.73 1.80 1.95 0.01 0.01 0.01
P,OS 0.24 0.23 0.21 0.24 0.22 0.:!4 0.24 0;24 0.24 0.71 0.67 0.74 L:.07 0.07 0.07
H,O- 0.13· 0.19 0.07 0.13 0.16 0.15 0.16 0.17 0.17 0.12 0.08 0.11 0.10 0.32 0.16
LOl 10.99 3.40 7.25 8.57 3.30 2.60 5.15 2.51 2.03' 5.33 10.91 4.68 7.04 7.86 6.33
TOT 96.50 98.07 96.05 97.61. 96.83. 96.67 97.59 97.16 97.57 101.33 101.06 102.19 101.39 100.38 101.00
ppm
.Rb 41.60 17.00 6.70 12.~0 16.90 22.60 18.80 33.50 17.60 107.50 73.30 84.90 0.01 0.01 0.01
Ba 696.00 419.60 147.00 373.20 446.60 693.90 419.40 870.50 594.70 518.00 287.90 453.10 37.10 26.30 30.70
Sr 248.30 332.20 330.40 375.00 314.90 721.20 538:00 559.20 796.80 47.60 119.40 49.10 102.70 83.30 126.70
Zr 189.90 172.80 176.10 181.00 176.20 177.60 177.80 181.70 169.00 342.80 310.30 343.70 58.50 56.40 56.80
Nb 7.10 6.90 8.30 7.60 8.10 8.30 8.10 9.90 9.50 16.00 15.50 16.60 1.50 2.70 3.30
Nr 52.30 163.90 175.30 150.00 186.20 162.10 167.10 164.80 170.00 58.00 83.50 82.70 270.00 267.60 318.80
Zo 50.60 84.40 127.10 89.90 120.70 92.50 97.70 105.60 105.70 61.90 114.60 104.20 120.40 66.50 67.80
Cr 64.20 69.00 62.10. 74.20 80.20 53.20 56.80 56.60 60.30 214.40 179.10 218.20 1,869.60 1,501.50 1,756.20
Cu 13.00 36.20 122.50 111.50 54.40 111.50 81.90 116.60 114.80 10.30 9.70 6.30 18.10 39.00 56.50
V 128.80 166.90 198.70 168.20 201.50 178.50 184.40 177.50 172.20 244.20 197.40 234.80 239.10 225.60 212.30
Y 27.40 23.10 26.10 26.70 23.00 26.50 2S.40 27.40 27.40 35.50 38.90 34.50 9.30 8.80 8.80
Sc. 21.10 18.60 21.40 22.80 19.20 16)0 18.30 20.90 20.00 21.60 17.70 21.60 34.70 31.50 23.60
Co 15.70 41.20 59.50 35.80 55.90 48.30 46.20 49.60 52.50 40.80 53.60 57.00 72.00 71.00 80.20
CIPW Norms. (%)
Quartz - 12.00 16.18 9.68 13.51 8.81: 9.26 10.56 9.44 35.04 10.09 34.67 30.25 15.12 14.52
Corundum - - - - - - - 5.35 - 8.58 4.29 -
Zireoo 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.07 0.07· 0.07 0.01 0.01 0.01
Ortheelase 16.63 5.64 1.60 4.26 6.40 7.31 6.54 11.84 5.21 16.87 11.84 11.87 0.06 0.06 0.06
A1bite 35.01 38.60 23.84 29.12 32.80 36.67 35.30 28.03 35.93 1.06 3.29 4.78 7.63 12.20 11.46
Anorthlte 15.19 12.25 26.96 21.98 18.01 15.81 17.90 1.7.88 17.00 17.41 34.65 9.74 17.88 29.11 26.21
;l>- Oiopside 11.72 14.93 5.57 21.11 5.98 12.70 13.09 10.93 12.02 - 12.32 - 0.29 5.10
oo
'0 Wollastooite 18.03 - - 0.91 - - - - - - - -
C::l>s Hyperathene - 4.82 9.15 - 7.74 4.34 4.39 6.05 5.60 11.09. 9.64 14.93 29.01 31.66 30.02
0x-' Olivioe - - - - - - , - -Chromite 0.02 0.02 0.02' 0.02 0.02 0.01' 0.01 0.01' 0.01 0.05 0.04 0.05 0.43 0.35 OAO
W Haematite 5.28 8.77 13.48 9.30 12.45 11.20. 10.31 11.65 11.71 9.85 12.89 12.01 10.04 10.20 11.28
1-.) Hmeoite 0.38 0.34 0.44 0.38 0.33 0.3,5 0.35 0.34 0.36 0.19 0.27 0.22 0.10 0.23 0.27
IV Spheoe - 2.19 2.31 2.74 2.34 i:ti . 2.40 2.32 2.32 - 3.33. - -' 0.90 0.85
-...l Apatite 0.67 0.58 0.56 0.64 0.56 0~61 0.62 0.61 ·0.60 1.76 1.76 1.81 0.18 0.18 0.18
Rutile - - - - - - - - - 1.46 - 1.48 0.48 - _ __~-
I
r
LRP3-11 LRP3-J2 LRP3-13 LRP3-14 LRP3-15 LRP3-16 LRP3-17 ' LRP3-18 LRP3-19 LRP3-20 LRP3-21 LRP3-22 DKL5-1 DKL5-2 DKL5-3
Depth (metres) 585.00 598.76 602.74 611.60 640.75 (47.00 658.00 662.10 675.90 683.25 700.50 713.85 260.95 278.12 320.00
Formalion Klip. Klip. Klip. Klip. Klip. _!g!£. Klip. Klip. Klip. Klip. Klip. Klip. Klip. Klip. Klip.
wt.%
SiO, 50.43 59.62 56.58 54.69 52.42 52.5'; 54.00 51.95 51.67 53.76 53.70 53.83 55.81 54.05 54.081
TlO, 0.4.1 0.6R 0.63 0..<6 0.46 0.44 0.44 0.38 0.44 0.41 0.39 0.42 1.13 1.18 1.14
AI,O) 10.96 15.25 14.41 13.64 11.00 10.45 11.13 10.75 11.46 11.13 9.98 9.80 13.61 13.60 13.06
Fe,O) 11.10 9.67 8.66 9.46 10.81 10.71 9.83 10.97 10.86 10.61 9.53 9.83 10.84 10.43 9.27
MnO 0.21 0.12 0.12 0.13 0.17 0.1'5 0.18 0.16 0.20 0.18 0.15 0.15 0.12 0.12 0.15
MgO 12.78 5.71 5.55 6.35 11.29 12.53 10.65 12.28 11.40 10.96 13.15 13.36 4.10 3.80 4.10
CaO 7.93 1.79 4.66 7.36 8.68 7.90 8.14 7.48 8.51 7.52 5.84 5.98 6.51 7.13 7.63 I
Na,O 1.51 3.i6 3.15 1.91 2.03 1.34 2.15 1.40 2.36 2.11 0.05 1.03 3.63 3.32 2.35
K,O 0.01 0.54 0.40 3.56 0.66 0.5i 0.47 0.21 0.34 ' 0.29 3.06 0.88 1.20 1.96 1.19 !
P,Os 0.06 0.11 0.11 0.09 0.06 0.05 0.06 0.06 0.06 0.06 0.05 0.06 0.25 0.26 0.25
H,O- 0.18 0.07 0.06 0.08 0.19 0.24 0.22 0.24 0.24 0.28 0.20 0.14 0.06 0.05 0.06
LOl 5.20 3.78 5.82 2.67 3.05 3.88 3.10 4.59 2.90 3.25 3.70 3.81 2.05 3.06 7.16
TOT 100.80 100.50 100.15 100.50 100.82 100.86 100:37 100.47 100.44 100.,56 99.80 99.29 99.31 98.96 100.44
ppm
Rb 0.01 7.20 3.40 91.80 15.30 13.00 10.50 1.20 6.30 5.50 86.10 20.60 17.50 31.60 16.50
Ba 29.90 351.50 535.90 5,433.00 472.90 583.50 300.60 148.40 257.40 184.10 2,285.50 358.20 537.70 1,177.60 486.90
Sr 153.40 136.60 326.50 410~30 165.90 116.20 208.50 101.00 126.10 101.10 87.80 78.70 656.90 613.20 261.70
Zr 50.20 88.80 80.20 76.50 57.40 56.iO 54.50 48.30 57.60 51.60 51.70 51.50 183.90 194.00 172.80
Nb 3.90 3.10 2.70 7.40 4.80 4.70 5.20 3.20 4.70 3.60 4.60 3.50 10.30 10.10 8.40
Ni 381.30 146.00 127.50 149.90 294.60 36t.60 258.90 401.00 345.30 337.50 399.10 355.40 119.90 108.20 149.60 I
Zn 68.80 71.40 71.20 69.60 67.90 73.W 57.70 72.80 72.90 73.30 61.10 65.00 95.40 , 95.70 100.70
Cr 2,074.70 592.30 404.40 365.40 1,308.10 1,912.10 1,501.10 2,199.20 1,994.90 1,991.60 2,506.40 2,386.30 31.70 36.90 43.60
Cu 51.10 35.00 36.10 67.00 52.90 41.10 49.90 33.10 51.80 24.10 27.50 26.80 344.40 98.70 131.00
V 194.80 234.90 200.60 174.80 187.20 176.10 180.40 187.40 188.50 185.60. 150.90 172.70 170.10 170.60 167.30
Y 9.30 11.10 10.80 16.00 9.70 10.60 11.00 7.70 9.70 8.80 9.20 8.00 23.20 23.70 19.30
Se 26.30 28.50 27.50 23.40 26.30 23.90 18.80 22.60 28.80 26.60 28.80 26.60 14.50 15.30 14.80
Co 79.30 65.10 52.10 50.40 70.60 70.('0 63.60 78.60 73.40 67.00 68.00 72.20 55.90 57.60 51.60
CIPW Norms. (%)
Quartz 9.58 28.02 19.82 8.72 8.11 IU9 11.31 12.45 6.52 12.08 12.41 14.67 13.94 11.10 18.46
Corundum - 6.66 0.54 - - - - - - - - - -
Zircon 0.01 ' 0.02 0.02 0.02 0.01 0.01' 0.01 0.01 0.01 0.01 0.01 0.01 0.04 0.04 0.04
Ortboelase 0.06 3.31 2.51 21.56 4.00 3,61 2.87 1.30 2.07 1.77 18.89 5.46 7.30 . 12.10 7.55
A1bile 13.39 27.66 28.27 16.53 17.60 11.'.12 18.74 12.39 20.5.2, 18.40 0.44 9.14 31.60 29.31 21.33
Anortbite 24.22 8.59 24.04 18.74 19.44 21.48 19.94 23.46 20.23 20.67 18.83 20.49 17.84 17.18
>- 23.
17
1
Diepside 12.16 - - 14.21 18.18 13.69 15.83 10.83 16.94 12.75 8.15 6.99 8.27 11.52 9.65
"C
"C WoUastonite - - - - - - - - - - - -
(1)
::s Hyperstbene 27.72 14.71 14.66 9.68 20.40 25.92 20.00 26.96 21.33 22.22 30.40 31.66 6.68 4.56 6.49
Q..
x' Olivine - - - - - - - - - - -Cbromite 0.47 0.13 0.09 0.08 0.29 0..13 0.33 0.49 0.44 0.44 0.56 0.54 0.01 0.01 0.01
v.> Haematite 11.63 10.01 9.19 9.68 11.08 11,08 10.13 11.47 11.16 10.93 9.94 10.31 11.15 10.88 9.94
IV Ilmenite 0.28 0.23 0.26' 0.28 0.27 _~18 0.26 0.15 0.25 0.21 0.08 0.09 0.31 0.31 0.39
IV
00 Spbene 0.75 - - 1.06 0.80 0.'$8 0.78 0.78 ,0.78 0.77 0.90 0.97 2.47 2.64 2.50
Apatite 0.15 0.27 0.28 0.22 0.15 0.15 0.15 0.15 0.15 0.15 0.13 0.15 0.61 0.65
Rutile - 0.58 0.53 - - - - - - - - - O:~----,-
':~
DKL5-6 DKL5-7 DKL5-7A DKL5-8 DKL5-8A DKLS-9 DKL5-10 DKL5-10A DKL5-12 DKL5-12A DKL5-14 DKLS-15 DKL5-15A DKL5-16 DKL5-16A
Depth (metres) 528.85 541.80 552.07 567.45 573.32 S83.0} 600.17 617.23 640.34 649.69 681.60 698.59 709.91 722.80 731.19
Formation Klip. Klip. Klip. Klip. Klip. J9!1'· Klin. Klin. Klip. Klip. Klip. Klip. Klip. Klip. Klip.
wt.%
sro, 43.36 52.65 53.87 52.39 53. 73 53.47 52.62 53.32 52.95 50.98 38.81 55.43 54.91 , 54.68 56.75
rio, 0.41 0.51 0.5R 0.52 0.50 0.49 0.48 0.14 0.48 0.58 1.03 0.64 0.58 0.56 0.57
AIlO, i2.14 12.74 13.07 12.54 12.79 12.70 12.38. 12.58 12.76 14.36 4.14 14.94 14.26 13.82 13.58
FelOJ 8.61 9.96 10.15 9..81 9.89 10.99 10.49 10.41 10.70 9.76 10.79 10.22 9.89 10.95 9.67
MnO 0.19 0.18 0.14 0.14 0.13 0.14 0.14 0.1.4 0.19 0.11 0.09 0.15 0.14 0.15 0.14
MgO 5.36 8.62 7.52 7:57 7.84 9.é5 9.00 8.77 8.78 5.62 17.68 5.82 6.50 7.40 6.97
CoO 13.70 i.38 7.66 7.76 7.26 6.5~ 6.47 6.82 7.99 7.97 14.87 5.70 8.05 7.18 7.13
NOlO 0.13 3.18 2.19 2.71 2.10 2.12 2.48 2.35 2.53 2.63 0.16 3.58 3.52 2.30 2.94
KlO 1.99 0.62 1.71 0.92 1.50 0.&3 1.55 2.00 1.29 0.53 0.06 1.15 0.49 1.47 1.82
PlO, 0.07 0.07 0.09 0.09 0.08 0.08 0.08 0.08 0.07 0.12 0.35 0.10 0.09 0.09 0.09
HlO- 0.11 0.20 0.12 0.16 0.13 0.17 0.10 0.09 0.18 0.14 0.46 0.11 0.11 . 0.11 0.05
LOl 14.10 3.78 2.32 2.50 2.97 3.15 2.42 2.42 2.49 6.76 10.44 2.32 2.26 2.46 1.98
TOT 100.17 99.89 99.42 97.11 98.92 100.:4 98.21 99.12 100.41 99.56 98.88 100.16 100.80 101.17 101.69
ppm
Rb 88.80 20.60 55.90 19.70 36.20 19.70 41.50 64.90 32.70 9.30 1.70 29.90 11.30 42.80 59.10
Ba 200.70 475.10 1,250.10 930.60 1,178.20 505.80 1,047.60 591.30 551.90 96.70 20.30 549.80 219.20 638.10 498.90
Sr 99.50 299.20 538.00 343.70 327.90 255."0 280.20 256.90 247.90 93.30 456.90 379.90 361.40 433.40 440.20
Zr 57.00 64.20 72.10 70.00 64.80 61.60 64.50 65.10 62.80 82.70 49.30 82.60 78.30 73.60 73.30
Nb 4.40 4.40 5.60 5.10 4.80 4";0 5.10 5.30 5.10 4.50 10.80 5.90 5.60 6.10 5.00
Ni 239.00 203.50 154.20 163.20 189.50 228.:'0 213.70 214.50 244.80 138.70 466.80 126.10 141.60 158.20 155.20
Zo 51.70 67.40 69.60 71.20 72.40 8LO 76.30 73.70 72.50 98.50 104.60 65.70 70.80 79.10 70.10
Cr 1,036.90 790.70 447.00 529.20 614.80 937.:;0 790.20 737.50 1,200.90 226.30 1,625.60 247.60 321.80 398.60 375.00
Cu 47.10 57.00 64.00 40.20 47.70 56.:;0 66.40 56.90 40.90 173.10 247.30 57.20 57.40 39.90 54.50
V 181.50 189.90 177.40 193.60 193.40 205.:;0 184.80 183.60 187.10 196.70 171.90 193.70 184.80 . 187.80
Y 10.80 12.30 14.50 13.00 12.30. 11.80 13.10 12.60 13.00 13.00 9.00 14.30 14.90 14.20 1174.1'<0'1
Sc 33.20 29.00 25.30 28.30 25.10 31.20 30.00 . 28.80 25.80 27.50 11.80 24.10 26.10 . 26.10 29.50
Co 50.80 59.00 60.00 62.10 64.50 72.10 64.40 65.60 61.50 59.50 78.90. 59.40 55.40 62.20 57.40
C1PW Norms. (%)
Quartz 7.70 7.34' 11.03 9.94 12.31 IV)9 8.41 8.08 7.62 12.21 11.16 9.81 12.20 10.76
Corundum - - - - - - - - - - - -
Zircon 0.01 0.01 0.01 0.01 0.01 O.oI 0.01 0.01 0.01 0.02 0.01 0.02 0.02 0.02 0.01
Ortheelase 13.72 3.83 10.44 5.77 9.27 5.1)6 9.59 12.26 7.81 3.38 0.40 6.97 2.95 8.83 10.82
Albite 1.28 28.05. 19.11 24.28 18.54 18.49 21.93 20.58 21.90 24.01 1.54 30.99 30.26 19.74 24.96
Anorthite 31.01 19.48 21.49 20.52 22.02 23.42 18.93 18.52 20.13 27.87 11.83 21.84 22.03 23.41 18.57
:> Diopside 33.51 13.44 12.55 14.53 11.03 650 10.29 12.64 14.86 9.61 51.19 3.95 12.97 8.62 11.83
"0
"0 Wollastonite 1.52 - - - - - - - - . - -
(1)
::s Hypenthene - 16.16 13.52 13.24 15.28 21.72 18.67 16.76 15.50 10.65 1.92 13.01 10.44 14.70 11.94
x0-' Olivine - - - - - - - - 17.10 -Chromite 0.26 0.18 0.10 0.12 0.14 0.21 0.18 0.16 0.26 0.05 0.40 0.05 0.07 0.09 0.08
W
Haematite 10.02 10.38 10.47 10.39 10.32 11.33 10.96 10.78 10.95 10.53 12.26 10.46 10.05 11.11 9.70
IV I1menite 0.38 0.35 0.30 0.30 0.26 .0125 0.27 0.27· 0.32 0.27 0.11 0.34 0.31 0.32 0.30
IV
\0 Sphene 0.67 0.85 1.09 0.97 0.94 0.92 0.89 - 0.80. 1.18 2.73 1.17 1.05 0.98 1.02
Apatite 0.19 0.17 0.22 0.23 0.20 0.20 0.20 0.20 0.17 0.31 0.94 0.24 0.22 0.22 0.21
Rutile - -- - - - - - - - - -.-
-'v.a. [j'fJLI~
-
DKL5-16B DKL5-17 DKL5-IH DKL5-17B DKL5-17C DKL5-18 DKL5-18A DKL5-18B DKL5-20
Depth (metres) 737.19 744.19 755.16 764.85 775.81 782.12 788.97 803.89 822.17
~tion Ktip. Klip. Ktio. Ktip. Klip, Klio, Ktip. Ktip. Ktip.
wt.%
SiO, 49.96 53.57 48.n 52.60 52.44 51.82 53.68 52.64 50.44
TiO, 0.50 0.46 O.t:? 0.45 0.46 0.42 0.41 0.37 0.43
Al,O) 11.55 10.97 11.:;1 11.11 11.64 10.17 10.23 8.86 10.18
Fe,O) 11.40 10.46 12.00 10.77 10.39 10.44 10.87 10.29 10.79
MnO 0.14 0.16 0.:.6 0.17 0.16 0.15 0.15 0.16 0.14
MgO 11.64 10.96 13.03 11.14 12.03 13.93 12.50 14.42 14.64
CoO 7.41 8.12 7.118 8.17 7.04 7.62 7.01 7.77 6.79
Na,O 1.82 1.81 1.46 1.98 1.75 1.42 1.14 0.06 1.17
K,O 1.09 0.90 0.:!2 0.23 0.92 0.40 0.28 0.37 0.79
P,Os 0.07 0.06 0,07 0.07 0.06 0.06 0.05 0.05 0.06
H,O- 0.17 0.17 0.17 0.19 0.16 0.08 0.16 0.16 0.13
LOl 3.17 3.00 4.37 3.13 3.39 3.67 4.21 4.56 3.98
TOT 98.92 100.64 100.26 100.01 100.44 100.18 100.69 99.71 99.54
ppm
Rb 28.90 23.40 4.60 3.40 24.90 12.10 5.50 16.10 23.30
Ba 415.10 311.60 76.70 77.10 338.10 128.70 108.00 49.70 272.60
Sr 196.10 185.60 219.)0 271.80 253.10 100.60 141.80 169.40 111.60
Zr 63.10 56.30 58.30 54.40 55.80 52.20 48.60 43.90 52.00
Nb 5.10 3.90 4.60 4.40 4.00 3.60 3.90 3.70 4.20
Ni 311.90 301.10 343.00 300.60 314.40 379.80 403.70 431.40 431.00
Zn 84.00 70.80 79.50 66.90 66.70 69.30 79.40 67.80 73.20
Cr 1.460.70 1.284.80 1,744.70 1,570.70 1,637.80 2,233.80 2,410.20 2,859.00 2,553.10
Cu 34.70 45.50 49.20 53.20 47.50 34.50 30.80 26.10 43.80
V 199.10 172.40 205.50 197.00 194.70 178.60 165.20 170.90 186.20
Y 13.00 10.90 12.70 11.30 10.80 9.80 8.90 8.90 9.40
Sc 30.20 27.30 27.50 32.40 24.60 25.60 24.60 29.30 26.'30
Co 73.60 68.80 80.90 69.50 74.50 76.70 78.30 74.90 79.40
CIPW Norms. (%)
Quartz 5.88 10.75 6.86 10.79 9.01 9.13 15.72 17.03 7.56
Corundum - - - - - - - -
Zircon 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01
Ortheelase 6.75 5.47 136 1.41 5.62 2.46 1.72 2.31 4.90
Albite 16.11 15.71 1291 17.33 15.28 12.46 10.01 0.53 10.37
Anorthite 21.08 19.66 2530 21.47 21.89 20.95 22.82 24.02 21.17
;> Diopside 12.17 15.77 1078 14.73 9.87 12.94 9.13 11.71 9.64
'"0 Wollastonite - - .. - - - - - -
'"0
Cl> Hypersthene 24.69 20.70 28.91 21.87 26.35 29.98 28.09 32.38 33.74:::
0. Olivine - - .. - - - - - -x' Chromite 0.33 0.28 0.39 0.35 0.36 0.50 0.54 0.65 0.~8
lj.) Haematite 11.93 10.73 12.54 11.14 10.72 10.83 11.29 10.83 11.31
lImenite 0.19 0.26 0.21 0.24 0.21 0.12 0.10 0.06 0.06
tv
lj.) Sphene 1.03 0.83 0:94 0.83 0.89 0.92 0.92 0.88 1.03
o Apatite 0.17 0.15 .0.17 0.17 0.15 0.15 0.12 0.12 0.15
Rutile - - .. ..-
-'_-,