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Iron Isotope Compositions of Coexisting Sulfide and Silicate Minerals in Sudbury-Type Ores from the Jinchuan Ni-Cu Sulfide Deposit: A Perspective on Possible Core-Mantle Iron Isotope Fractionation

文献类型：期刊论文

作者Wang, Peiyao2,3,4; Niu, Yaoling1,2,3,5; Sun, Pu2,3; Wang, Xiaohong2,3; Guo, Pengyuan2,3; Gong, Hongmei2,3; Duan, Meng2,3; Shen, Fangyu2,3,4; Shi, Yining5; Xue, Song5
刊名MINERALS
出版日期2021-05-01
卷号11期号:5页码:30
关键词equilibrium iron isotope fractionation Jinchuan magmatic sulfide deposit net-textured sulfide ores pyrrhotite chalcopyrite pentlandite olivine and pyroxenes core-mantle Fe isotope fractionation
DOI10.3390/min11050464
通讯作者Wang, Peiyao(peiyao.wang@qdio.ac.cn) ; Niu, Yaoling(yaoling.niu@durham.ac.uk)
英文摘要Many studies have shown that the average iron (Fe) isotope compositions of mantle-derived rocks, mantle peridotite and model mantle are close to those of chondrites. Therefore, it is considered that chondrite values represent the bulk Earth Fe isotope composition. However, this is a brave assumption because nearly 90% of Fe of the Earth is in the core, where its Fe isotope composition is unknown, but it is required to construct bulk Earth Fe isotope composition. We approach the problem by assuming that the Earth's core separation can be approximated in terms of the Sudbury-type Ni-Cu sulfide mineralization, where sulfide-saturated mafic magmas segregate into immiscible sulfide liquid and silicate liquid. Their density/buoyancy controlled stratification and solidification produced net-textured ores above massive ores and below disseminated ores. The coexisting sulfide minerals (pyrrhotite (Po) > pentlandite (Pn) > chalcopyrite (Cp)) and silicate minerals (olivine (Ol) > orthopyroxene (Opx) > clinopyroxene (Cpx)) are expected to hold messages on Fe isotope fractionation between the two liquids before their solidification. We studied the net-textured ores of the Sudbury-type Jinchuan Ni-Cu sulfide deposit. The sulfide minerals show varying delta Fe-56 values (-1.37--0.74 parts per thousand (Po) < 0.09-0.56 parts per thousand (Cp) < 0.53-1.05 parts per thousand (Pn)), but silicate minerals (Ol, Opx, and Cpx) have delta Fe-56 values close to chondrites (delta Fe-56 = -0.01 +/- 0.01 parts per thousand). The heavy delta Fe-56 value (0.52-0.60 parts per thousand) of serpentines may reflect Fe isotopes exchange with the coexisting pyrrhotite with light delta Fe-56. We obtained an equilibrium fractionation factor of Delta Fe-56(silicate-sulfide) approximate to 0.51 parts per thousand between reconstructed silicate liquid (delta Fe-56 approximate to 0.21 parts per thousand) and sulfide liquid (delta Fe-56 approximate to -0.30 parts per thousand), or Delta Fe-56(silicate-sulfide) approximate to 0.36 parts per thousand between the weighted mean bulk-silicate minerals (delta Fe-56([0.70ol,0.25opx,0.05cpx]) = 0.06 parts per thousand) with weighted mean bulk-sulfide minerals (delta Fe-56 approximate to -0.30 parts per thousand). Our study indicates that significant Fe isotope fractionation does take place between silicate and sulfide liquids during the Sudbury-type sulfide mineralization. We hypothesize that significant iron isotope fractionation must have taken place during core-mantle segregation, and the bulk Earth may have lighter Fe isotope composition than chondrites although Fe isotope analysis on experimental sulfide-silicate liquids produced under the varying mantle depth conditions is needed to test our results. We advocate the importance of further research on the subject. Given the close Fe-Ni association in the magmatic mineralization and the majority of the Earth's Ni is also in the core, we infer that Ni isotope fractionation must also have taken place during the core separation that needs attention.
资助项目National Science Foundation of China (NSFC)[41630968] ; National Science Foundation of China (NSFC)[91958215] ; NSFC-Shandong Joint Fund for Marine Science Research Centers[U1606401] ; 111 Project[B18048]
WOS研究方向Geochemistry & Geophysics ; Mineralogy ; Mining & Mineral Processing
语种英语
出版者MDPI
WOS记录号WOS:000662400000001
源URL[http://ir.qdio.ac.cn/handle/337002/176876]  
专题中国科学院海洋研究所
通讯作者Wang, Peiyao; Niu, Yaoling
作者单位1.Univ Durham, Dept Earth Sci, Durham DH1 3LE, England
2.Chinese Acad Sci, Inst Oceanol, Qingdao 266071, Peoples R China
3.Qingdao Natl Lab Marine Sci & Technol, Lab Marine Geol, Qingdao 266061, Peoples R China
4.Univ Chinese Acad Sci, Coll Earth & Planetary Sci, Beijing 100049, Peoples R China
5.China Univ Geosci, Sch Earth Sci & Resources, Beijing 100083, Peoples R China
推荐引用方式
GB/T 7714		 Wang, Peiyao,Niu, Yaoling,Sun, Pu,et al. Iron Isotope Compositions of Coexisting Sulfide and Silicate Minerals in Sudbury-Type Ores from the Jinchuan Ni-Cu Sulfide Deposit: A Perspective on Possible Core-Mantle Iron Isotope Fractionation[J]. MINERALS,2021,11(5):30.
APA Wang, Peiyao.,Niu, Yaoling.,Sun, Pu.,Wang, Xiaohong.,Guo, Pengyuan.,...&Li Shan.(2021).Iron Isotope Compositions of Coexisting Sulfide and Silicate Minerals in Sudbury-Type Ores from the Jinchuan Ni-Cu Sulfide Deposit: A Perspective on Possible Core-Mantle Iron Isotope Fractionation.MINERALS,11(5),30.
MLA Wang, Peiyao,et al."Iron Isotope Compositions of Coexisting Sulfide and Silicate Minerals in Sudbury-Type Ores from the Jinchuan Ni-Cu Sulfide Deposit: A Perspective on Possible Core-Mantle Iron Isotope Fractionation".MINERALS 11.5(2021):30.

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来源：海洋研究所

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