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Redox state of the Baogutu reduced porphyry Cu deposit in the Central Asian Orogenic belt

文献类型：期刊论文

作者Zhu, Bin1,2; Zhang, Hong-Fu1; Shen, Ping1; Su, Ben-Xun1; Xiao, Yan1; He, Yong-Sheng3
刊名ORE GEOLOGY REVIEWS
出版日期2018-10-01
卷号101页码:803-818
关键词Baogutu reduced porphyry Cu deposit Redox condition Primary magma Fe isotope Ore-forming fluid
ISSN号0169-1368
DOI10.1016/j.oregeorev.2018.08.024
英文摘要Reduced porphyry Cu deposits are scarce and their origins remain enigmatic. The Late Carboniferous Baogutu reduced porphyry Cu deposit in the western Junggar Terrane, NW China, provides an opportunity to address this issue. In this study, we conducted systematic analyses in terms of petrography, mineral chemistry, major elements, trace elements and Fe isotopes to investigate the redox state of its primary magma and further constrain the origin of Baogutu copper deposit. Based on the petrological observation and mineral chemistry, two magmatic stages have been recognized during the formation of ore-forming diorite. The early stage is characterized by the crystallization of magnetite and high Mg-# [Mg/(Mg + Fe2+)1 hornblende under oxidized condition (Delta NNO > 2.36, calculated by the equation given by Scaillet and Evans (1999). The late stage is characterized by the crystallization of ilmenite and low Mg-# biotite under reduced condition (Delta NNO < -0.6). The large decrease of oxygen fugacity (log fO(2), more than 3 units) between the two stages may result from the contamination of organic carbon during the emplacement of magma. In addition, major and trace element compositions of the Baogutu ore-forming diorites show the affinity of arc magmas which are like those that host oxidized porphyry Cu deposits. In this study, we first report the Fe isotopic compositions of reduced porphyry copper deposit and discuss its application for the origin of ore deposit. The delta Fe-56 values of less altered diorites and granodiorites (+ 0.083%o and +0.054%o) fall into the field of arc magmas, consistent with their major and trace elements results. The delta Fe-56 values of sulfides (chalcopyrite and pyrite) show a large span (0.228 to + 0.614%o) and the early formed disseminated sulfides are enriched in light Fe isotopes relative to the late formed vein-hosted sulfides, which indicates that hydrothermal fluid evolves toward heavy Fe isotope enrichment. The average delta Fe-56 of all hydrothermal sulfides (chalcopyrite and pyrite) is much higher than that of Baogutu silicate rocks, which demonstrates that the hydrothermal fluid are Fe isotopically heavy and it well explains the positive correlations between delta Fe-56 and indices of hydrothermal alteration for altered plutonic rocks and wall rocks. In summary, major elements, trace elements and Fe isotopes of the Baogutu porphyries show the affinity of arc magmas, same as the typical oxidized porphyry Cu deposits. Both petrological observations and Fe isotope features of the Baogutu porphyry Cu deposit indicate that the primary magma of Baogutu porphyries is oxidized and its reduced features are secondary.
WOS关键词IRON ISOTOPE FRACTIONATION ; MO-AU DEPOSIT ; NW-CHINA ; WEST JUNGGAR ; TECTONIC EVOLUTION ; OXIDIZED MAGMAS ; OXYGEN-FUGACITY ; MOSSBAUER-SPECTROSCOPY ; CHALCOPHILE ELEMENTS ; NORTHERN XINJIANG
资助项目National Natural Science Foundation of China, China[91014007] ; National Natural Science Foundation of China, China[91214203] ; National Natural Science Foundation of China, China[U1303293] ; National Natural Science Foundation of China, China[41390442]
WOS研究方向Geology ; Mineralogy ; Mining & Mineral Processing
语种英语
WOS记录号WOS:000448092400043
出版者ELSEVIER SCIENCE BV
资助机构National Natural Science Foundation of China, China ; National Natural Science Foundation of China, China ; National Natural Science Foundation of China, China ; National Natural Science Foundation of China, China ; National Natural Science Foundation of China, China ; National Natural Science Foundation of China, China ; National Natural Science Foundation of China, China ; National Natural Science Foundation of China, China
源URL[http://ir.iggcas.ac.cn/handle/132A11/89151]  
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Zhu, Bin
作者单位1.Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China
2.Beijing Res Inst Uranium Geol, Beijing 100029, Peoples R China
3.China Univ Geosci, State Key Lab Geol Proc & Mineral Resources, Beijing 100083, Peoples R China
推荐引用方式
GB/T 7714		 Zhu, Bin,Zhang, Hong-Fu,Shen, Ping,et al. Redox state of the Baogutu reduced porphyry Cu deposit in the Central Asian Orogenic belt[J]. ORE GEOLOGY REVIEWS,2018,101:803-818.
APA Zhu, Bin,Zhang, Hong-Fu,Shen, Ping,Su, Ben-Xun,Xiao, Yan,&He, Yong-Sheng.(2018).Redox state of the Baogutu reduced porphyry Cu deposit in the Central Asian Orogenic belt.ORE GEOLOGY REVIEWS,101,803-818.
MLA Zhu, Bin,et al."Redox state of the Baogutu reduced porphyry Cu deposit in the Central Asian Orogenic belt".ORE GEOLOGY REVIEWS 101(2018):803-818.

入库方式： OAI收割

来源：地质与地球物理研究所

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