| 藏西措勤县日阿与斑（玢）岩有关的铜矿床的矿床地质特征与成矿时代 |
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| 引用本文：辛洪波，曲晓明.2006.Geological characteristics and ore_forming epoch of Ri'a copper deposit related to bimodal rock series in Coqen County, western Tibet [J].Mineral Deposits,25(4):477~482 |
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| 基金项目:国家重点基础研究发展规划973项目（2002CB412605） |
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| 中文摘要:藏西地区措勤县日阿铜矿产于拉萨地块内，是一个与二长花岗斑岩岩株有关的矽卡岩型铜矿床。由矿体中金云母测得的40Ar/39Ar成矿年龄为（87.69±0.64）Ma，MSWD=0.42，与二长花岗斑岩的锆石U_Pb SHRIMP 年龄（90.1 Ma）一致。同时，矿区内的辉绿玢岩脉，与二长花岗斑岩具有相近的年龄（87.2 Ma）及相似的岩石地球化学特征，它们共同构成了一套含铜的双峰式岩石组合，代表了中—晚白垩世拉萨地块内的伸展构造环境下的铜成矿事件。文章指出，造成该矿区铜矿化的双峰式岩系（二长花岗斑岩—辉绿玢岩组合）是由班公湖—怒江洋壳向南俯冲，在碰撞后伸展阶段形成的。该矿床的发现表明，西藏高原除了与板块缝合带有关的斑岩型铜矿（包括玉龙、冈底斯、班公湖—怒江3条斑岩铜矿带）外，拉萨地块内部还有一期与双峰式岩系有关的斑岩_矽卡岩型铜矿成矿事件。 |
| 中文关键词:地质学 矽卡岩型铜矿床 矿床地质特征 金云母40Ar/39Ar年龄 成矿构造环境 藏西措勤 |
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| Geological characteristics and ore_forming epoch of Ri'a copper deposit related to bimodal rock series in Coqen County, western Tibet |
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| Abstract:Lying southeast of Coqen County in western Tibet and tectonically within Lhasa terrain, the Ri'a copper deposit is a skarn copper deposit related to an adamellite porphyry stock. The40Ar/39Ar mineralization age of phlogopite in the Ri'a copper deposit is (87.69±0.64) Ma (MSWD =0.42), which is in accordance with the U_Pb SHRIMP age of zircon (90.1 Ma). Moreover, the diabase prophyrite in the ore district is accompanied by disseminated copper mineralization, whose age (87.2 Ma) and rock geochemical characteristics are close to those of the adamellite porphyry. They together constitute a copper_bearing bimodal rock assemblage, representing a copper mineralization event under the Middle_Late Cretaceous extensional tectonic environment in Lhasa terrain. Researches show that the bimodal rock series resulting in copper mineralization was formed during the extensional period after the southward subduction of Bangonghu_Nujiang oceanic crust. The discovery of the deposit shows that, besides the porphyry copper deposits in Yulong, Gangdese and Bangonghu_Nujiang porphyry_type copper ore belts related to the plate suture zone, there existed a porphyry_skarn copper ore_forming event related to the bimodal rock series in Lhasa terrain. |
| keywords:geology, skarn copper deposit, geological characteristics, 40Ar/39Ar age of phlogopite, tectonic environment for mineralization, Coqen County in western Tibet |
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