| 西藏雄村特大型铜金矿床容矿火山岩的成因及其对成矿的贡献 |
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| 引用本文： | 曲晓明,辛洪波,徐文艺.西藏雄村特大型铜金矿床容矿火山岩的成因及其对成矿的贡献[J].地质学报,2007,81(7):964-971. |
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| 作者姓名： | 曲晓明 辛洪波 徐文艺 |
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| 作者单位： | 中国地质科学院矿产资源研究所,北京,100037 |
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| 基金项目： | “973”项目《印度与亚洲大陆主碰撞带成矿作用》(编号2002CB412605)资助的成果 |
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| 摘 要： | 岩石学、地球化学和Nd、Sr、Pb同位素研究表明,西藏冈底斯铜矿带雄村特大型铜金矿床的容矿火山岩为一套具超浅成侵入特点的英安斑岩,SiO2含量集中在61.97%~64.31%之间,富Na2O、低K2O,Na2O/K2O比值平均为5.25。地球化学上明显富集大离子不相容元素Rb、Ba、K、Sr、Pb,同时高场强元素Nb、Ta、Ti处于亏损状态。Sr、Nd同位素组成变化范围小(87Sr/86Sr=0.705154~0.708267,ISr=0.704299~0.705357;143Nd/144Nd=0.512730~0.512931),具有富集地幔特征;Pb同位素组成显示出地幔铅与造山带铅的双重特性(206Pb/204Pb=18.170~18.432,207Pb/204Pb=15.485~15.546,208Pb/207Pb=37.993~38.392)。研究指出它们是早侏罗世(195Ma)由雅鲁藏布江洋壳向欧亚大陆之下俯冲形成的岛弧火山岩,岩浆源区具有EM1型原始地幔富集特征,同时有一定数量的俯冲沉积物加入了地幔源区的部分熔融。根据雄村矿床的成矿时代和矿化特征,笔者认为该矿床的成因类型与胶东焦家式金矿一致,为破碎带蚀变岩型。旦狮庭组容矿火山岩对成矿的贡献在于作为矿源层为矿床提供了成矿金属元素。
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| 关 键 词： | 岩石成因 容矿火山岩 雄村铜金矿床 冈底斯铜矿带 西藏 |
| 修稿时间： | 4/8/2007 12:00:00 AM |
Petrogenesis of the Ore-Hosting Volcanic Rocks and Their Contribution to Mineralization in Xiongcun Superlarge Cu-Au Deposit, Tibet |
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| QU Xiaoming,XIN Hongbo,XU Wenyi.Petrogenesis of the Ore-Hosting Volcanic Rocks and Their Contribution to Mineralization in Xiongcun Superlarge Cu-Au Deposit, Tibet[J].Acta Geologica Sinica,2007,81(7):964-971. |
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| Authors: | QU Xiaoming XIN Hongbo XU Wenyi |
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| Institution: | Institute of Mineral Resources, CAGS, Beijing , 100037 |
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| Abstract: | Petrological,geochemical and Nd,Sr,Pb isotopic studies indicate that the ore-hosting volcanic rocks of Xiongcun supperlarge copper-gold deposit in the Gangdese copper belt, Tibet belong to dacite porphyry with ultro-shallow emplacement.Their SiO2 contents vary in a narrow range of 61.97% to 64.31% and Na2O is high relative to low K2O with a mean Na2O/K2O ratio of 5.25.Geochemically they are notably rich in large-ion incompatibale elements(LILE) Rb, Ba, K, Sr, Pb. Meanwhile their high field strength elements(HFSE)are in depletion state.Sr and Nd isotopic compositons yield a small variation range(87Sr/86Sr=0.705154~0.708267, ISr=0.704299~0.705357;143Nd/144Nd=0.51273~0.512931). Further study indicates that they were arc volcanics originated from subduction of Yalozangpo oceanic crust beneath the Euroasian continent.The magma source had EM1-type primary mantle richment,and some subducted sediments were involved in partial melting of the mantle source.Based on the ore-forming age and mineralization characteristics of the deposit, the paper points out that the genetic type of the deposit is the same as that of the Jiaojia-type gold deposit of Shandong and belongs to fracture-controlled altered rock type. |
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| Keywords: | petrogenesis ore-hosting volcanic rocks Xiongcun Cu-Au deposit Gangdese copper belt Tibet |
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