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The effect of Fe-Ti oxide separation on iron isotopic fractionation during basalt differentiation

文献类型：期刊论文

作者Zhao, Jian2; Wang, Xiao-Jun2; Chen, Li-Hui2; Hanyu, Takeshi3; Shi, Jin-Hua5; Liu, Xiao-Wen5; Kawabata, Hiroshi4; Xie, Lie-Wen1
刊名CONTRIBUTIONS TO MINERALOGY AND PETROLOGY
出版日期2022-10-01
卷号177期号:10页码:15
ISSN号0010-7999
关键词Fe isotopes Alkaline basalt Fractional crystallization Titanomagnetite St. Helena
DOI10.1007/s00410-022-01967-w
英文摘要Separation of Fe-Ti oxides during magmatic differentiation plays an important role in controlling Fe isotopic evolution of residual magmas. Titanomagnetite (Tmag) is a common Fe-Ti oxide phenocryst phase in evolved basaltic lavas, but the effect of its separation on Fe isotopic evolution of residual melts remains poorly understood. Here we explore this issue with an Fe isotopic study on a suite of cogenetic alkaline volcanic rocks (range from picrobasalt to trachyandesite) and their titanomagnetite phenocrysts from St. Helena Island (South Atlantic). Results show that whole-rock delta Fe-57 values vary from 0.04 to 0.32 parts per thousand with decreasing MgO, and ulvospinel-rich (X ' usp approximate to 0.6) titanomagnetite phenocrysts have consistently lower delta Fe-57 than corresponding bulk samples with an average Delta Fe-57(Tmag-whole rock) (delta Fe-57(Tmag) - delta Fe-57(whole rock)) value of - 0.05 +/- 0.02 parts per thousand (2SD, N = 6). This value together with the speculated crystallization temperatures (similar to 1100 +/- 50 degrees C) of these titanomagnetite phenocrysts determine an equilibrium titanomagnetite-melt fractionation factor of Delta Fe-57(Tmag-melt) = (- 0.094 +/- 0.038) x 10(6)/T-2. Quantitative calculations involving this isotopic fractionation factor and previously suggested olivine-melt and clinopyroxene-melt isotopic fractionation factors can well reproduce the Fe isotopic evolution of St. Helena lavas. Specifically, the Fe isotopic variation before titanomagnetite saturation (MgO > 5 wt%) is dominated by fractional crystallization and accumulation of olivine and clinopyroxene, while that after titanomagnetite saturation is determined by fractional crystallization of multiphases including titanomagnetite, olivine and clinopyroxene. This study, combined with published mineral-melt fractionation factors for other Fe-Ti oxides, indicates that the removal of ulvospinel-rich (X'usp > 0.5) titanomagnetite and near-pure ilmenite results in an increase of delta Fe-57 in evolved magmas, whereas separation of near-pure magnetite drives residual melt towards lighter Fe isotopic compositions.
WOS关键词MAFIC LAYERED INTRUSION ; MAGMATIC DIFFERENTIATION ; OXYGEN FUGACITY ; VOLCANIC-ROCKS ; MANTLE ; SYSTEMATICS ; ISLAND ; REDOX ; CRYSTALLIZATION ; EVOLUTION
资助项目National Natural Science Foundation of China[42130310] ; National Natural Science Foundation of China[41973001]
WOS研究方向Geochemistry & Geophysics ; Mineralogy
语种英语
出版者SPRINGER
WOS记录号WOS:000869220100001
资助机构National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China
源URL[http://ir.iggcas.ac.cn/handle/132A11/107782]  
专题地质与地球物理研究所_岩石圈演化国家重点实验室
通讯作者Wang, Xiao-Jun
作者单位1.Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China
2.Northwest Univ, Dept Geol, State Key Lab Continental Dynam, Xian 710069, Peoples R China
3.Japan Agcy Marine Earth Sci & Technol, Res Inst Marine Geodynam, Yokosuka, Kanagawa 2370061, Japan
4.Kochi Univ, Fac Sci & Technol, Kochi 7808520, Japan
5.Nanjing Univ, Sch Earth Sci & Engn, State Key Lab Mineral Deposits Res, Nanjing 210023, Peoples R China
推荐引用方式
GB/T 7714		 Zhao, Jian,Wang, Xiao-Jun,Chen, Li-Hui,et al. The effect of Fe-Ti oxide separation on iron isotopic fractionation during basalt differentiation[J]. CONTRIBUTIONS TO MINERALOGY AND PETROLOGY,2022,177(10):15.
APA Zhao, Jian.,Wang, Xiao-Jun.,Chen, Li-Hui.,Hanyu, Takeshi.,Shi, Jin-Hua.,...&Xie, Lie-Wen.(2022).The effect of Fe-Ti oxide separation on iron isotopic fractionation during basalt differentiation.CONTRIBUTIONS TO MINERALOGY AND PETROLOGY,177(10),15.
MLA Zhao, Jian,et al."The effect of Fe-Ti oxide separation on iron isotopic fractionation during basalt differentiation".CONTRIBUTIONS TO MINERALOGY AND PETROLOGY 177.10(2022):15.

入库方式： OAI收割

来源：地质与地球物理研究所

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