祁漫塔格东段晚三叠世-早侏罗世花岗岩LA-ICP-MS锆石U-Pb年龄及其地质意义

    LA-ICP-MS zircon U-Pb dating of the Late Triassic-Early Jurassic granites in the eastern part of Qimantag area and its geological significance

    • 摘要: 祁漫塔格东段拉陵高里河地区晚三叠世—早侏罗世花岗岩组合为高SiO(2 72.18%~76.55%)、高K2O(4.08%~5.32%)的碱性花岗岩组合,具有明显的负Eu异常(δEu平均值为0.28)。岩石组合为二长花岗岩+正长花岗岩,采用LA-ICP-MS技术测得二长花岗岩和正长花岗岩的年龄分别为205.1±1.0 Ma和199.5±1.2 Ma。该套花岗岩组合与拉陵高里河地区的矽卡岩型多金属矿关系密切,初步确定祁漫塔格地区晚三叠世—早侏罗世花岗岩组合也是一期重要的成矿岩浆建造。

       

      Abstract: The Late Triassic-Early Jurassic granitic assemblage in the eastern part of Qimantag area has high SiO2 content (72.18%~76.55%), high K2O content (4.08%~5.32%) and obvious negative Eu anomaly (average σEu value being 0.28).The granitic assem-blage is composed of monzogranite and syenogranite, whose ages were precisely redefined by the LA-ICP-MS zircon U-Pb meth-od, being 205.1±1.0 Ma and 199.5±1.2 Ma respectively.This granitic assemblage has close relationship with skarn-type polymetallic deposits in Lalinggaoli area.Therefore, the authors preliminarily hold that the Late Triassic-Early Jurassic granitic assemblage is proba-bly an important ore-forming magmatic formation in the eastern part of Qimantag area.

       

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