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Light Mg isotopes in mantle-derived lavas caused by chromite crystallization, instead of carbonatite metasomatism

文献类型：期刊论文

作者Su, Ben-Xun1,2,3; Hu, Yan2; Teng, Fang-Zhen2; Xiao, Yan4; Zhang, Hong-Fu3,4,5; Sun, Yang2,4; Bai, Yang1,2,3; Zhu, Bin4; Zhou, Xin-Hua3,4; Ying, Ji-Feng3,4
刊名EARTH AND PLANETARY SCIENCE LETTERS
出版日期2019-09-15
卷号522页码:79-86
关键词carbonatite metasomatism lithospheric mantle Mg isotopes peridotite xenoliths chromite crystallization
ISSN号0012-821X
DOI10.1016/j.epsl.2019.06.016
英文摘要Carbonatite metasomatism plays an important role in modifying the composition of Earth's mantle, however, its effect on mantle Mg isotopic composition is poorly constrained. Here, we report high precision mineral Mg isotope data for three suites of mantle peridotite xenoliths that experienced variable degrees of carbonatite metasomatism. The delta Mg-26 values of minerals in these xenoliths are variable and range from -0.32 to -0.11 parts per thousand in olivine, from -0.28 to -0.09 parts per thousand in orthopyroxene, from -0.27 to -0.05 parts per thousand in clinopyroxene, from 0.06 to 0.44 parts per thousand in spinel and from -0.61 to -0.37 parts per thousand in garnet. Calculated bulk-rock delta Mg-26 values of the peridotites vary from -0.27 to -0.10 parts per thousand, falling within and slightly higher than the normal mantle range (-0.25 +/- 0.07 parts per thousand). The coexisting minerals are in isotopic equilibrium, with clinopyroxene delta Mg-26 values correlated with the carbonatite metasomatic indices such as MgO and Na2O in orthopyroxene. These results suggest that carbonatite metasomatism does not produce light Mg isotopic signature in mantle peridotites as previously suggested, instead it might slightly elevate their delta Mg-26 values. Therefore, carbonatite-metasomatized peridotites in the mantle cannot be the primary source rocks of low-delta Mg-26 mantle-derived magmas. Instead, fractional crystallization and accumulation of chromite during ascent of the basaltic magmas may explain the isotopically light basalts, as supported by the covariations of delta Mg-26 with chemical indices of chromite crystallization (e.g., Cr, V, Fe and Ti). Consequently, chromite crystallization may significantly influence the physiochemical processes on the genesis of basalts, which would require comprehensive evaluation in future studies. (C) 2019 Elsevier B.V. All rights reserved.
WOS关键词SPINEL PERIDOTITE XENOLITHS ; LITHOSPHERIC MANTLE ; TRACE-ELEMENT ; WESTERN VICTORIA ; O ISOTOPES ; MAGNESIUM ; FRACTIONATION ; CHINA ; ORIGIN ; BASALTS
资助项目National Key Research and Development Program of China[2017YFC0601306] ; National Natural Science Foundation of China[41673037] ; National Natural Science Foundation of China[41688103] ; National Natural Science Foundation of China[41729001] ; National Natural Science Foundation of China[91755205]
WOS研究方向Geochemistry & Geophysics
语种英语
WOS记录号WOS:000478708900009
出版者ELSEVIER
资助机构National Key Research and Development Program of China ; National Key Research and Development Program of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Key Research and Development Program of China ; National Key Research and Development Program of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Key Research and Development Program of China ; National Key Research and Development Program of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Key Research and Development Program of China ; National Key Research and Development Program of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China
源URL[http://ir.iggcas.ac.cn/handle/132A11/92946]  
专题地质与地球物理研究所_中国科学院矿产资源研究重点实验室
通讯作者Su, Ben-Xun; Teng, Fang-Zhen
作者单位1.Chinese Acad Sci, Inst Geol & Geophys, Key Lab Mineral Resources, Beijing 100029, Peoples R China
2.Univ Washington, Dept Earth & Space Sci, Seattle, WA 98195 USA
3.Univ Chinese Acad Sci, Beijing 100049, Peoples R China
4.Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China
5.Northwest Univ, Dept Geol, State Key Lab Continental Dynam, Xian 710069, Shaanxi, Peoples R China
推荐引用方式
GB/T 7714		 Su, Ben-Xun,Hu, Yan,Teng, Fang-Zhen,et al. Light Mg isotopes in mantle-derived lavas caused by chromite crystallization, instead of carbonatite metasomatism[J]. EARTH AND PLANETARY SCIENCE LETTERS,2019,522:79-86.
APA Su, Ben-Xun.,Hu, Yan.,Teng, Fang-Zhen.,Xiao, Yan.,Zhang, Hong-Fu.,...&Ying, Ji-Feng.(2019).Light Mg isotopes in mantle-derived lavas caused by chromite crystallization, instead of carbonatite metasomatism.EARTH AND PLANETARY SCIENCE LETTERS,522,79-86.
MLA Su, Ben-Xun,et al."Light Mg isotopes in mantle-derived lavas caused by chromite crystallization, instead of carbonatite metasomatism".EARTH AND PLANETARY SCIENCE LETTERS 522(2019):79-86.

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来源：地质与地球物理研究所

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