中国科学院机构知识库网格
Chinese Academy of Sciences Institutional Repositories Grid
Platinum-group element geochemistry of the layered intrusions in the Emeishan large igneous province, SW China: Implications for the principal controls on magmatic sulfide immiscibility

文献类型:期刊论文

作者YU-WEI SHE;  XIE-YAN SONG;  LIE-MENG CHEN;   SONG-YUE YU;  XIANG-KUN ZHU;  JUN-NIAN YI;  JUN-HAO HU
刊名American Journal of Science
出版日期2017
卷号317页码:483–513
关键词Platinum-group Elements (Pge) Sulfide Segregation Crustal Contamination Fractional Crystallization Fe-ti Oxides Layered Intrusion Emeishan Large Igneous Province
英文摘要

It is widely accepted that the incorporation of external sulfur via crustal contamination is an important trigger for sulfide immiscibility that generates Ni-Cu-(PGE) sulfide mineralization, yet other controlling factors for sulfide immiscibility may also be present. The late Permian Panzhihua, Baima, Hongge, Xinjie and Taihe layered intrusions in the Emeishan Large Igneous Province (ELIP, SW China), are well-endowed with Fe-Ti oxide deposits, whereas their sulfide mineralization is mainly sub-economic. For example, the lower part of the Xinjie intrusion hosts a few thin PGE-rich ore layers, yet other ELIP layered intrusions do not contain any Ni-Cu sulfide mineralization and are PGE-depleted (0.01–1 ppb). Compared with the PGE-undepleted Emeishan high-Ti basalts that are genetically related to the intrusions, the extent of PGE depletion and elevated Cu/Pd ratios (up to 3.2106 ) of the Panzhihua, Baima, Taihe and Hongge intrusions suggest PGEdepletion in their parental magmas due to early-stage sulfide removal. Sr-Nd isotopic compositions of the Panzhihua, Baima and Taihe intrusions suggest crustal contamination was insignificant and sulfide saturation produced mainly by crustal sulfur input was unlikely. MELTS modeling shows that extensive fractionation of chromite, olivine and clinopyroxene in deep-seated magma chambers may have induced early-stage sulfide saturation of the primary magmas. The relatively high sulfide contents in the Fe-Ti oxide layers at Panzhihua, Baima, Hongge and Taihe indicate a close relationship between the second-stage sulfide immiscibility and extensive Fe-Ti oxide crystallization. Positive correlations between sulfur and total Fe2O3, V and TiO2 suggest that Fe-Ti oxide (magnetite and ilmenite) crystallization may have triggered the secondstage sulfide saturation via sharply lowering the Fe concentration and oxygen fugacity of the magmas. Moderate degree of crustal contamination for the Xinjie Fe-Ti oxide-barren rocks may have induced sulfide saturation and accumulation at the lower part of the intrusion. Our calculations indicate that the Xinjie PGE-rich rocks have high R-factors (1000 –10000), which are ascribed to PGE-upgrading of the sulfides via reaction with new replenishments of PGE-undepleted magmas. A few Panzhihua, Baima and Taihe samples that contain higher PGE concentrations suggest that the early-stage sulfide droplets at depths were entrained in later magma pulses delivered to shallower magma chambers. The very high R-factors determined by mass balance calculation, implies a good potential for discovering more PGE mineralization in the deep-seated intrusions of the magma plumbing system.

语种英语
源URL[http://ir.gyig.ac.cn/handle/42920512-1/8385]  
专题地球化学研究所_矿床地球化学国家重点实验室
作者单位1.Laboratory of Isotope Geology, Ministry of Land and Resources, Institute of Geology, ChineseAcademy of Geological Sciences, Beijing 100037, PR China
2.State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, PR China
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YU-WEI SHE;XIE-YAN SONG;LIE-MENG CHEN; SONG-YUE YU;XIANG-KUN ZHU;JUN-NIAN YI;JUN-HAO HU. Platinum-group element geochemistry of the layered intrusions in the Emeishan large igneous province, SW China: Implications for the principal controls on magmatic sulfide immiscibility[J]. American Journal of Science,2017,317:483–513.
APA YU-WEI SHE;XIE-YAN SONG;LIE-MENG CHEN; SONG-YUE YU;XIANG-KUN ZHU;JUN-NIAN YI;JUN-HAO HU.(2017).Platinum-group element geochemistry of the layered intrusions in the Emeishan large igneous province, SW China: Implications for the principal controls on magmatic sulfide immiscibility.American Journal of Science,317,483–513.
MLA YU-WEI SHE;XIE-YAN SONG;LIE-MENG CHEN; SONG-YUE YU;XIANG-KUN ZHU;JUN-NIAN YI;JUN-HAO HU."Platinum-group element geochemistry of the layered intrusions in the Emeishan large igneous province, SW China: Implications for the principal controls on magmatic sulfide immiscibility".American Journal of Science 317(2017):483–513.

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来源:地球化学研究所

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