秦祁昆结合部瓦勒根金矿床含矿斑岩体岩石学和LA-ICP-MS锆石U-Pb年龄
Petrology and LA-ICP-MS zircon U-Pb age of the ore-bearing porphyry in the Walegen gold deposit at the juncture of the Qinling-Qilian-Kunlun orogens
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摘要: 秦祁昆结合部广泛发育中三叠世岛弧钙碱性岩浆作用，已发现大量与其相关的斑岩型—夕卡岩型铜金、铜钼和银铅锌多金属矿床。瓦勒根金矿床是近年来在该区新发现的一个斑岩型金矿床，矿区内出露有众多的石英斑岩和花岗斑岩，且均发育有金矿化，其中石英斑岩与金矿化关系更为密切。LA-ICP-MS锆石U-Pb年龄表明，花岗斑岩形成于中三叠世（237Ma），其中包含有丰富的晚古生代及元古宙继承性锆石。这一特征与区域上的斑岩型铜金矿床含矿岩体具有相似性。进一步说明，古特提斯洋在秦祁昆结合部发生向北消减所形成的岩浆捕获了早于三叠纪的壳源和幔源物质，从而形成了岛弧钙碱性岩浆及相关的斑岩型—夕卡岩型矿床组合。
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关键词:
- LA-ICP-MS锆石U-Pb年龄 /
- 花岗斑岩 /
- 瓦勒根金矿 /
- 秦祁昆结合部
Abstract: The middle Triassic calc-alkaline arc magmatism and its related porphyry-skarn type Cu-Au, Cu-Mo and Ag-Pb-Zn polymetallic deposits are widespread at the juncture of Qinling-Qilian-Kunlun orogens. The Walegen Au deposit is a newly-discovered porphyry deposit. The host rocks of the Walegen deposit are quartz porphyry and granite porphyry, with the quartz porphyry more closely related to gold mineralization. The results of zircon U-Pb analysis by using LA-ICP-MS technique indicate that the granite porphyry was formed in middle Triassic (237Ma), and contained voluminous Paleozoic-Proterozoic inherited zircons. These characteristics are similar to characteristics of other porphyry Cu-Au deposits in this region. These data suggest that the magmas produced by northward subduction of Paleo-tethys ocean captured pre-Triassic crust and mantle materials, resulting in the arc magmatism and the formation of related porphyry-skarn deposit assemblage at the juncture of Qinling-Qilian-Kunlun orogens. -
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