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| The effect of Fe-Ti oxide separation on iron isotopic fractionation during basalt differentiation | |
| Zhao, Jian1; Wang, Xiao-Jun1; Chen, Li-Hui1; Hanyu, Takeshi2; Shi, Jin-Hua3; Liu, Xiao-Wen3; Kawabata, Hiroshi4; Xie, Lie-Wen5 | |
| 2022-10-01 | |
| Source Publication | CONTRIBUTIONS TO MINERALOGY AND PETROLOGY
 |
| ISSN | 0010-7999 |
| Volume | 177Issue:10Pages:15 |
| Abstract | 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. |
| Keyword | Fe isotopes Alkaline basalt Fractional crystallization Titanomagnetite St. Helena |
| DOI | 10.1007/s00410-022-01967-w |
| Funding Organization | 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 |
| WOS Keyword | MAFIC LAYERED INTRUSION ; MAGMATIC DIFFERENTIATION ; OXYGEN FUGACITY ; VOLCANIC-ROCKS ; MANTLE ; SYSTEMATICS ; ISLAND ; REDOX ; CRYSTALLIZATION ; EVOLUTION |
| Language | 英语 |
| Funding Project | National Natural Science Foundation of China[42130310] ; National Natural Science Foundation of China[41973001] |
| Funding Organization | 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 |
| WOS Research Area | Geochemistry & Geophysics ; Mineralogy |
| WOS Subject | Geochemistry & Geophysics ; Mineralogy |
| WOS ID | WOS:000869220100001 |
| Publisher | SPRINGER |
| Citation statistics | |
| Document Type | 期刊论文 |
| Identifier | http://ir.iggcas.ac.cn/handle/132A11/107782 |
| Collection | 岩石圈演化国家重点实验室 |
| Corresponding Author | Wang, Xiao-Jun |
| Affiliation | 1.Northwest Univ, Dept Geol, State Key Lab Continental Dynam, Xian 710069, Peoples R China 2.Japan Agcy Marine Earth Sci & Technol, Res Inst Marine Geodynam, Yokosuka, Kanagawa 2370061, Japan 3.Nanjing Univ, Sch Earth Sci & Engn, State Key Lab Mineral Deposits Res, Nanjing 210023, Peoples R China 4.Kochi Univ, Fac Sci & Technol, Kochi 7808520, Japan 5.Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China |
| Recommended Citation 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. |
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