The effect of crystal-plastic deformation on isotope and trace element distribution in zircon: Combined BSE, CL, EBSD, FEG-EMPA and NanoSIMS study

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dc.contributor.authorKovaleva, Elizaveta
dc.contributor.authorKlotzli, Urs
dc.contributor.authorHabler, Gerlinde
dc.contributor.authorHuet, Benjamin
dc.contributor.authorGuan, Yun-bin
dc.contributor.authorRhede, Dieter
dc.date.accessioned2018-05-28T06:21:35Z
dc.date.available2018-05-28T06:21:35Z
dc.date.issued2016
dc.description.abstractPlastically-deformed zircon grains from granulite-facies (Ivrea-Verbano Zone, Southern Alps, Italy) and amphibolite-facies (Tauern Window, Eastern Alps, Austria) shear zones have been investigated. The main focus was on the effects of crystal-plastic deformation on the distribution of trace elements and their isotopes. Zircon grains reveal crystal-plastic deformation patterns in form of (I) gradual bending of the lattice (high density of free dislocations), (II) highly-deformed margins revealing a combination of low- and high-angle boundaries and gradual bending of the lattice, and (III) a low-angle boundary (LAB) network. Chemical and isotopic maps and profiles show that trace elements in zircon are re-distributed in all plastically-deformed domains. Changes in trace element composition along LABs are sometimes revealed by brighter CL and darker BSE signal. LABs and domains of high free-dislocation density have depletion in U, Y, Yb and enrichment in Ce, La and Nd, while Ti and P are either enriched, depleted or remain unaffected, and Hf demonstrates stability. Y and Yb are decreased in concentration across LABs, and have oscillating concentration in domains of high free-dislocation density. Our observations confirm that crystal-plastically deformed domains in zircon act as effective pathways for trace cations. The Pb isotopic system is disturbed by crystal-plastic deformation microstructures, as indicated by relative 207Pb/206Pb ages showing significant discordance in plastically-deformed zircon domains. In deformed domains, a positive correlation between dislocation density and the degree of isotopic age distortion is observed. Fractured or porous domains and domains with high density of (sub)grain boundaries are enriched in common Pb from the matrix, and thus show significantly older relative 207Pb/206Pb ages than pristine domains. In contrast, Pb loss occurs in domains with high free-dislocation density at a distance of 5-10 μm from the grain boundary, caused by out-diffusion of radiogenic Pb. This study adds to a growing database on the consequences of crystal-plastic deformation for trace elements and isotopic systems in zircon. We provide additional evidence that such deformation cannot be neglected and may have important implications for zircon geochronology and geochemistry.en_ZA
dc.description.versionAccepted manuscripten_ZA
dc.identifier.citationKovaleva, E., Klötzli, U., Habler, G., Huet, B., Guan, Y., & Rhede, D. (2016). The effect of crystal-plastic deformation on isotope and trace element distribution in zircon: Combined BSE, CL, EBSD, FEG-EMPA and NanoSIMS study. Chemical Biology. Advanced online publication. DOI:10.1016/j.chemgeo.2016.12.030en_ZA
dc.identifier.issn0009-2541
dc.identifier.urihttp://dx.doi.org/10.1016/j.chemgeo.2016.12.030
dc.identifier.urihttp://hdl.handle.net/11660/8324
dc.language.isoenen_ZA
dc.publisherElsevieren_ZA
dc.rights.holder© 2016. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/en_ZA
dc.subjectZirconen_ZA
dc.subjectTrace elementsen_ZA
dc.subjectIsotopic distortionen_ZA
dc.subjectEBSDen_ZA
dc.subjectNanoSIMSen_ZA
dc.subjectCrystal-plastic deformationen_ZA
dc.titleThe effect of crystal-plastic deformation on isotope and trace element distribution in zircon: Combined BSE, CL, EBSD, FEG-EMPA and NanoSIMS studyen_ZA
dc.typeArticleen_ZA
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