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  4. 岩石圈演化国家重点实验室
Oxidation of the deep big mantle wedge by recycled carbonates: Constraints from highly siderophile elements and osmium isotopes

文献类型：期刊论文

作者Cai, Ronghua4; Liu, Jingao4; Pearson, D. Graham1; Li, Dongxu4; Xu, Yong4; Liu, Sheng-Ao4; Chu, Zhuyin5; Chen, Li-Hui2; Li, Shuguang3,4
刊名GEOCHIMICA ET COSMOCHIMICA ACTA
出版日期2021-02-15
卷号295页码:207-223
ISSN号0016-7037
关键词Highly siderophile elements Mantle sulfides Carbonate recycling Intraplate basalts Big mantle wedge Mg-Zn isotopes
DOI10.1016/j.gca.2020.12.019
英文摘要Widespread Cenozoic intraplate basalts from eastern China offer the opportunity to investigate the consequences of interaction between the stagnant Pacific slab and overlying asthenosphere and chemical heterogeneity within this "big mantle wedge". We present and compile a comprehensive study of highly siderophile elements and Mg-Zn isotopes of this magmatic suite (60 samples including nephelinites, basanites, alkali basalts and tholeiites). The large-scale Mg-Zn isotopic anomalies documented in these basalts have been ascribed to mantle hybridization by recycled Mg-carbonates from the stagnant western Pacific plate. Our results reveal that the nephelinites and basanites are characterized by unfractionated platinum-group element (PGE) patterns normalized to primitive upper mantle (PUM) (e.g., Pd-N/Ir-N normalized to PUM = 1.1 +/- 0.8, 1 sigma), relatively high total PGE contents (e.g., Ir = 0.25 +/- 0.14 ppb) and modern mantle-like Os-187/Os-188 (0.142 +/- 0.020). These characteristics are coupled with lighter Mg isotope (delta(26)mg = -0.48 +/- 0.07 parts per thousand) and heavier (delta Zn-66 isotope = +0.46 +/- 0.06 parts per thousand) compositions compared to the mantle values (delta Mg-26: -0.25 +/- 0.07 parts per thousand; delta Zn-66: +0.18 +/- 0.05 parts per thousand). Together, these data are interpreted to reflect the oxidative breakdown of low proportions of mantle sulfides in the sources of these small-degree melts, likely caused by recycled carbonates, which then release chalcophile-siderophile elements into carbonatitic melts. By contrast, the contemporaneous alkali basalts and tholeiites are characterized by highly fractionated PGE patterns (e.g., Pd-N/Ir-N = 4.4 +/- 3.3; Ir = 0.037 +/- 0.027 ppb) and radiogenic Os-187/Os-188 (0.279 +/- 0.115) coupled with less fractionated Mg-Zn isotope compositions (delta Mg-26: -0.39 +/- 0.05 parts per thousand; delta Zn-66: +0.35 +/- 0.03 parts per thousand). In combination with other isotopic (e.g., Sr-Nd) and chemical (SiO2, Ce/Pb, Ba/Th, Fe/Mn) constraints, the alkali basalts and tholeiites were derived from higher degree melting of ancient pyroxenite-bearing mantle in addition to mixing with the aforementioned nephelinitic and basanitic melts. Collectively, we suggest that deep recycled carbonates promoted melting within the "big mantle wedge" leading to the generation of Cenozoic intraplate basalts across eastern China and the "redox freezing of carbonates" may cause the oxidation of Fe-0 and S2-. This process may provide an important mechanism to oxidize mantle sulfides and transfer precious metals from deep mantle to crust. (C) 2020 Elsevier Ltd. All rights reserved.
资助项目National Key R&D Program of China[2019YFA0708400] ; National Key R&D Program of China[2020YFA0714800] ; National Key R&D Program of China[2019YFC0605403] ; National Natural Science Foundation of China[41730214] ; National Natural Science Foundation of China[41822301] ; National Natural Science Foundation of China[41790451] ; China "1000 Youth Talents Program" ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP)[2019QZKK0801] ; 111 project[B18048] ; pre-research Project on Civil Aerospace Technologies - Chinese National Space Administration[D 020202]
WOS研究方向Geochemistry & Geophysics
语种英语
出版者PERGAMON-ELSEVIER SCIENCE LTD
WOS记录号WOS:000614115300012
资助机构National Key R&D Program of China ; National Key R&D Program of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; China "1000 Youth Talents Program" ; China "1000 Youth Talents Program" ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; 111 project ; 111 project ; pre-research Project on Civil Aerospace Technologies - Chinese National Space Administration ; pre-research Project on Civil Aerospace Technologies - Chinese National Space Administration ; National Key R&D Program of China ; National Key R&D Program of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; China "1000 Youth Talents Program" ; China "1000 Youth Talents Program" ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; 111 project ; 111 project ; pre-research Project on Civil Aerospace Technologies - Chinese National Space Administration ; pre-research Project on Civil Aerospace Technologies - Chinese National Space Administration ; National Key R&D Program of China ; National Key R&D Program of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; China "1000 Youth Talents Program" ; China "1000 Youth Talents Program" ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; 111 project ; 111 project ; pre-research Project on Civil Aerospace Technologies - Chinese National Space Administration ; pre-research Project on Civil Aerospace Technologies - Chinese National Space Administration ; National Key R&D Program of China ; National Key R&D Program of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; China "1000 Youth Talents Program" ; China "1000 Youth Talents Program" ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; Second Tibetan Plateau Scientific Expedition and Research Program (STEP) ; 111 project ; 111 project ; pre-research Project on Civil Aerospace Technologies - Chinese National Space Administration ; pre-research Project on Civil Aerospace Technologies - Chinese National Space Administration
源URL[http://ir.iggcas.ac.cn/handle/132A11/100057]  
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Liu, Jingao
作者单位1.Univ Alberta, Dept Earth & Atmospher Sci, Edmonton, AB T6G 2E3, Canada
2.Northwest Univ, Dept Geol, State Key Lab Continental Dynam, Xian 710069, Peoples R China
3.Univ Sci & Technol China, Sch Earth & Space Sci, CAS Key Lab Crust Mantle Mat & Environm, Hefei 230026, Peoples R China
4.China Univ Geosci, State Key Lab Geol Proc & Mineral Resources, Beijing 100083, Peoples R China
5.Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China
推荐引用方式
GB/T 7714		 Cai, Ronghua,Liu, Jingao,Pearson, D. Graham,et al. Oxidation of the deep big mantle wedge by recycled carbonates: Constraints from highly siderophile elements and osmium isotopes[J]. GEOCHIMICA ET COSMOCHIMICA ACTA,2021,295:207-223.
APA Cai, Ronghua.,Liu, Jingao.,Pearson, D. Graham.,Li, Dongxu.,Xu, Yong.,...&Li, Shuguang.(2021).Oxidation of the deep big mantle wedge by recycled carbonates: Constraints from highly siderophile elements and osmium isotopes.GEOCHIMICA ET COSMOCHIMICA ACTA,295,207-223.
MLA Cai, Ronghua,et al."Oxidation of the deep big mantle wedge by recycled carbonates: Constraints from highly siderophile elements and osmium isotopes".GEOCHIMICA ET COSMOCHIMICA ACTA 295(2021):207-223.

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来源：地质与地球物理研究所

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