Geological characteristics, metallogenesis, and tectonic setting of porphyry–skarn Cu deposits in East Kunlun Orogen
Geological characteristics, metallogenesis, and tectonic setting of porphyry–skarn Cu deposits in East Kunlun Orogen
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DOI：
10.1002/gj.3130
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发表时间：
2018-01
影响因子：
1.8
通讯作者：
Hui Wang;C. Feng;Rongxi Li;Daxin Li
中科院分区：
文献类型：
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作者：
Hui Wang;C. Feng;Rongxi Li;Daxin Li
东昆仑造山带是中国最重要的三叠纪多金属成矿带，位于华中造山带西段。本文总结了鄂西地区赛什塘、虎头崖、喀尔确卡等典型斑岩-矽卡岩型铜多金属矿床的地质特征（地层、构造、与矿相关的岩体、围岩蚀变、矿体）、成矿流体和成矿物质、成矿年代学、岩石地球化学等。新疆斑岩-矽卡岩型铜矿主要分布在祁、鄂拉山带的构造单元中。其中，矽卡岩型铜矿提供了绝大部分的铜矿资源，主要产于三叠系花岗岩类与火山-沉积岩的接触带（如，奥陶系-志留系滩间山群和早中三叠世洪水川群），矽卡岩及矿体主要受层间滑动构造控制。斑岩型铜矿床的成矿流体为岩浆与大气降水的混合流体，矽卡岩型铜矿床的成矿流体主要为岩浆成因。矽卡岩中石榴子石和辉石的δ 18 O值较高（>10‰），硫同位素组成变化较大（δ 34 S值介于−8.9‰ ~ 11.0‰），表明矽卡岩型铜矿的成矿物质部分来自围岩。在详细的野外调查的基础上，我们确定了4种铜矿化类型，包括侵入体内的细脉浸染型Cu（Mo，Au）矿化，近源夕卡岩型Cu（Fe，Pb，Zn，Au）矿化，远源夕卡岩型Cu矿化和远源夕卡岩型Pb-Zn（Cu）矿化。斑岩-矽卡岩型铜矿床与岩浆活动有关，岩浆活动主要发生在235-218 Ma。与矿石有关的花岗岩类主要是钙碱性I型花岗岩，来自前寒武纪基底岩石的部分熔融，并有不同程度的地幔成分参与。结合区域构造演化，我们认为，鄂温克造山带的成矿作用始于阿尼玛卿洋的闭合（~238 Ma），并在后碰撞环境（~225 Ma）达到高潮。
The East Kunlun Orogen (EKO), as the west segment of the Central China Orogen, is the most important Triassic polymetallic metallogenic belt in China. In this paper, we summarize the geological characteristics (stratigraphy, structure, ore‐related plutons, wall rock alteration, and orebodies), ore‐forming fluids and materials, geochronology, and petro‐geochemistry of the representative porphyry–skarn Cu–polymetallic deposits, including the Saishitang, Hutouya, and Kaerqueka deposits in the EKO. The porphyry–skarn Cu deposits in the EKO are mainly distributed in tectonic units of the Qimantagh Belt and the Elashan Belt. Among them, the skarn Cu deposits provide the majority of Cu resources, which mainly occur in the contact zone between the Triassic granitoids and the volcanic–sedimentary rocks (e.g., the Ordovician–Silurian Tanjianshan Group and the Early to Middle Triassic Hongshuichuan Group), and the skarn and orebodies are mainly controlled by interlayer–gliding structures. Ore‐forming fluids of the porphyry Cu deposits are magmatic mixed with meteoric water, whereas the fluids of skarn Cu deposits are mainly of magmatic origin. The higher δ18O (>10‰) of garnet and pyroxene in prograde skarn and wide range of sulphur isotopic compositions (δ34S values from −8.9‰ to 11.0‰) suggest that ore‐forming materials of skarn Cu deposits were partially derived from the country rocks. Based on detailed field investigations, we identified four Cu mineralization types, including veinlet–disseminated Cu (Mo, Au) mineralization occurring within the intrusions, proximal skarn Cu (Fe, Pb, Zn, Au) mineralization, distal skarn Cu mineralization, and distal skarn Pb–Zn (Cu) mineralization. The porphyry–skarn Cu deposits are associated with magmatism that occurred mainly during 235–218 Ma. The ore‐related granitoids are mostly calc‐alkaline I‐type granites, derived from partial melting of the Precambrian basement rocks with various degrees of involvement of mantle components. Combined with the regional tectonic evolution, we conclude that the Cu mineralization in the EKO began with the closure of A'nyemaqen Ocean (~238 Ma) and subsequently culminated in a postcollisional setting (~225 Ma).