1. Zinc isotopic fractionation between aqueous fluids and silicate magmas: An experimental study
- Author
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Fei Wu, Fang Huang, Haihao Guo, Ying Xia, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Magma - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Bayerisches Geoinstitut (BGI), Universität Bayreuth, CAS Key Laboratory of Crust–Mantle Materials and Environments [Hefei], School of Earth and Space Sciences [Hefei], University of Science and Technology of China [Hefei] (USTC)-University of Science and Technology of China [Hefei] (USTC)-Chinese Academy of Sciences [Beijing] (CAS), State Key Laboratory of Geological Processes and Mineral Resources [Wuhan] (GPMR), and China University of Geosciences [Wuhan] (CUG)
- Subjects
Incompatible element ,010504 meteorology & atmospheric sciences ,Inorganic chemistry ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences ,chemistry.chemical_element ,Fractionation ,Zinc ,010502 geochemistry & geophysics ,01 natural sciences ,Silicate ,Equilibrium fractionation ,chemistry.chemical_compound ,Igneous rock ,Isotope fractionation ,chemistry ,[SDU]Sciences of the Universe [physics] ,13. Climate action ,Geochemistry and Petrology ,[SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology ,Igneous differentiation ,0105 earth and related environmental sciences - Abstract
International audience; Fluids in magmas play a key role in magma differentiation and transportation of economic metals for ore deposits. As a chalcophile and incompatible element, zinc and its isotopes have been increasingly applied to study the magmatic-hydrothermal processes. However, zinc isotopic fractionation between aqueous fluids and magmas has not been well constrained. Here we experimentally determined equilibrium fractionation factors of Zn isotopes between aqueous fluids and silicate magmas (Δ66Znfluid-magma= δ66Znfluid - δ66Znmagma). The results reveal that aqueous fluids are isotopically heavier than the coexisting silicate magmas. No correlation between Δ66Znfluid-magma and temperature or chlorine contents in fluids is observed under our experimental conditions. Instead, Δ66Znfluid-magma is negatively corresponded with NBO/T of the melt (the ratio of non-bridge oxygen and tetrahedron ions), and positively correlated with the molar ratio of Al/(0.5K+Ca+Fe) in the bulk magmas, suggesting the controlling of silicate composition on Zn isotope fractionation. Our data therefore indicate that the isotopically heavier Zn in the fluids exsolved from magmas may account for the higher δ66Zn of pegmatites and high-silica granitic rocks. Moreover, involvement of magmatic fluids can explain the highly variable and remarkably heavier Zn isotopic signatures of fumaroles, thermal spring waters, and seafloor hydrothermal fluids compared to the igneous rocks. This study provides information that can be used to guide research using Zn isotopes to trace fluid activity and magmatism.
- Published
- 2021