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Significant Zr isotope variations in single zircon grains recording magma evolution history

Zircons widely occur in magmatic rocks and often display internal zonation finely recording the magmatic history. Here, we presented in situ high-precision (2SD <0.15‰ for δ(94)Zr) and high–spatial-resolution (20 µm) stable Zr isotope compositions of magmatic zircons in a suite of calc-alkaline p...

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Autores principales: Guo, Jing-Liang, Wang, Zaicong, Zhang, Wen, Moynier, Frédéric, Cui, Dandan, Hu, Zhaochu, Ducea, Mihai N.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: National Academy of Sciences 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7474644/
https://www.ncbi.nlm.nih.gov/pubmed/32817493
http://dx.doi.org/10.1073/pnas.2002053117
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author Guo, Jing-Liang
Wang, Zaicong
Zhang, Wen
Moynier, Frédéric
Cui, Dandan
Hu, Zhaochu
Ducea, Mihai N.
author_facet Guo, Jing-Liang
Wang, Zaicong
Zhang, Wen
Moynier, Frédéric
Cui, Dandan
Hu, Zhaochu
Ducea, Mihai N.
author_sort Guo, Jing-Liang
collection PubMed
description Zircons widely occur in magmatic rocks and often display internal zonation finely recording the magmatic history. Here, we presented in situ high-precision (2SD <0.15‰ for δ(94)Zr) and high–spatial-resolution (20 µm) stable Zr isotope compositions of magmatic zircons in a suite of calc-alkaline plutonic rocks from the juvenile part of the Gangdese arc, southern Tibet. These zircon grains are internally zoned with Zr isotopically light cores and increasingly heavier rims. Our data suggest the preferential incorporation of lighter Zr isotopes in zircon from the melt, which would drive the residual melt to heavier values. The Rayleigh distillation model can well explain the observed internal zoning in single zircon grains, and the best-fit models gave average zircon–melt fractionation factors for each sample ranging from 0.99955 to 0.99988. The average fractionation factors are positively correlated with the median Ti-in-zircon temperatures, indicating a strong temperature dependence of Zr isotopic fractionation. The results demonstrate that in situ Zr isotope analyses would be another powerful contribution to the geochemical toolbox related to zircon. The findings of this study solve the fundamental issue on how zircon fractionates Zr isotopes in calc-alkaline magmas, the major type of magmas that led to forming continental crust over time. The results also show the great potential of stable Zr isotopes in tracing magmatic thermal and chemical evolution and thus possibly continental crustal differentiation.
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spelling pubmed-74746442020-09-18 Significant Zr isotope variations in single zircon grains recording magma evolution history Guo, Jing-Liang Wang, Zaicong Zhang, Wen Moynier, Frédéric Cui, Dandan Hu, Zhaochu Ducea, Mihai N. Proc Natl Acad Sci U S A Physical Sciences Zircons widely occur in magmatic rocks and often display internal zonation finely recording the magmatic history. Here, we presented in situ high-precision (2SD <0.15‰ for δ(94)Zr) and high–spatial-resolution (20 µm) stable Zr isotope compositions of magmatic zircons in a suite of calc-alkaline plutonic rocks from the juvenile part of the Gangdese arc, southern Tibet. These zircon grains are internally zoned with Zr isotopically light cores and increasingly heavier rims. Our data suggest the preferential incorporation of lighter Zr isotopes in zircon from the melt, which would drive the residual melt to heavier values. The Rayleigh distillation model can well explain the observed internal zoning in single zircon grains, and the best-fit models gave average zircon–melt fractionation factors for each sample ranging from 0.99955 to 0.99988. The average fractionation factors are positively correlated with the median Ti-in-zircon temperatures, indicating a strong temperature dependence of Zr isotopic fractionation. The results demonstrate that in situ Zr isotope analyses would be another powerful contribution to the geochemical toolbox related to zircon. The findings of this study solve the fundamental issue on how zircon fractionates Zr isotopes in calc-alkaline magmas, the major type of magmas that led to forming continental crust over time. The results also show the great potential of stable Zr isotopes in tracing magmatic thermal and chemical evolution and thus possibly continental crustal differentiation. National Academy of Sciences 2020-09-01 2020-08-18 /pmc/articles/PMC7474644/ /pubmed/32817493 http://dx.doi.org/10.1073/pnas.2002053117 Text en Copyright © 2020 the Author(s). Published by PNAS. http://creativecommons.org/licenses/by/4.0/ https://creativecommons.org/licenses/by/4.0/This open access article is distributed under Creative Commons Attribution License 4.0 (CC BY) (http://creativecommons.org/licenses/by/4.0/) .
spellingShingle Physical Sciences
Guo, Jing-Liang
Wang, Zaicong
Zhang, Wen
Moynier, Frédéric
Cui, Dandan
Hu, Zhaochu
Ducea, Mihai N.
Significant Zr isotope variations in single zircon grains recording magma evolution history
title Significant Zr isotope variations in single zircon grains recording magma evolution history
title_full Significant Zr isotope variations in single zircon grains recording magma evolution history
title_fullStr Significant Zr isotope variations in single zircon grains recording magma evolution history
title_full_unstemmed Significant Zr isotope variations in single zircon grains recording magma evolution history
title_short Significant Zr isotope variations in single zircon grains recording magma evolution history
title_sort significant zr isotope variations in single zircon grains recording magma evolution history
topic Physical Sciences
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7474644/
https://www.ncbi.nlm.nih.gov/pubmed/32817493
http://dx.doi.org/10.1073/pnas.2002053117
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