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对滇东南燕山晚期老君山花岗岩开展了全岩主-微量元素、Sr-Nd-Pb同位素、锆石LA-MC-ICPMS U-Pb定年研究。结果表明该岩体岩石化学成分总体上属于高K钙碱性系列,其铝饱和指数ACNK多大于1.1;标准矿物计算显示大多数样品含有标准刚玉分子(1%~5%);认为老君山花岗岩为过铝-强过铝S型花岗岩,是古老地壳物质部分熔融的产物,其源岩可能为滇东南地区中-古元古代结晶基底中的一套变质泥岩为主,含少量变质硬砂岩的泥砂质副变质岩。根据锆石U-Pb定年结果,可将该复式岩体形成年龄分为80~88 Ma、90~98 Ma、100~118 Ma等三幕。老君山花岗岩成岩与锡矿化时代的一致性,表明都龙锡矿化与燕山期岩浆热液活动关系密切,老君山花岗岩是都龙锡锌多金属矿床成矿物质的主要源区。滇东南个旧、白牛厂和都龙等三个超大型矿床的成矿和成岩时代的耦合关系可能暗示其经历了相似的动力学背景,均与燕山期岩浆事件和华南岩石圈伸展密切相关。
The LA-MC-ICPMS U-Pb dating of the whole rock, Sr-Nd-Pb isotope and zircon was carried out on the Laoshanju granite in the late Yanshanian southeast Yunnan. The results show that the petrochemical composition of the rock generally belongs to the high-K calc-alkaline series with an ACNK of more than 1.1; the standard mineral calculation shows that most of the samples contain standard corundum molecules (1% -5%); the Laojunshan granite It is a peraluminous-strongly Al-S-type granite, which is a product of partial melting of the ancient crust. The source rocks may be mainly metamorphic mudstones in the Meso-Paleoproterozoic crystalline basement in southeastern Yunnan, with minor amounts of metamorphic hard-rock Sedimentary metamorphic rocks. According to the results of U-Pb zircon dating, the formation ages of the complex rock mass can be divided into three episodes, ie, 80-88 Ma, 90-98 Ma, and 100-118 Ma. Laojunshan granite diagenesis and tin mineralization era of consistency, indicating that the Du Long tin mineralization and Yanshanian magmatic hydrothermal activities are closely related, Laojunshan granite is the main source of Du Long tin zinc polymetallic deposits. The coupling relationship between the mineralization and diagenesis ages of Gejiu, Baigun and Dulong in southeastern Yunnan may imply that they experienced similar dynamic background, which are closely related to the Yanshanian magmatism events and the extension of the South China lithosphere.