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浙西地区地处下扬子陆块东南缘,区内中生代岩浆侵入活动强烈,与成矿作用关系密切。与锡成矿作用有关的双溪口花岗岩锆石LA-ICP-MS U-Pb定年结果显示,成岩年龄为130.4±1.1 Ma。岩石具有富SiO_2,高Ga、Zr、Nb和Y,贫Al_2O_3、Sr、Ba、Ti和P,Eu强烈负异常(δ_(Eu)=0.08~0.42)的地球化学特征,Zr饱和温度为848~887℃,属铝质A型花岗岩。锆石Hf同位素ε_(Hf)(t)变化范围集中在-4.66~-2.50之间,二阶段模式年龄t_(DM2)变化于1192~1311 Ma之间,暗示其源区物质主要来自中元古代地壳。结合区域地质矿产资料综合分析,认为浙西地区与锡相关的成矿事件发生于132~127 Ma之间,受控于早白垩世伸展环境下壳幔岩浆的相互混合作用。
The western Zhejiang is located in the southeastern margin of the Lower Yangtze block. The Mesozoic magmatic intrusions in the area are intense and closely related to the mineralization. LA-ICP-MS dating of zircons from the Shuangxiu granite associated with tin mineralization shows that the diagenetic age was 130.4 ± 1.1 Ma. The geochemical characteristics of the rocks are rich in SiO_2, high Ga, Zr, Nb and Y, poorly depleted in Al_2O_3, Sr, Ba, Ti and P, Eu with δ_ (Eu) = 0.08 ~ 0.42. The Zr saturation temperature is 848 ~ 887 ℃, is an aluminum A-type granite. The zircon Hf isotopes ε_ (Hf) (t) ranged from -4.66 to -2.50, and the two-stage model t_ (DM2) varied from 1192 to 1311 Ma, indicating that the source materials mainly originated from Mesoproterozoic Crust. According to the comprehensive analysis of regional geology and mineral resources, it is considered that the tin-related metallogenic event in western Zhejiang occurred between 132 and 127 Ma, controlled by the interaction of crust-mantle magma in the Early Cretaceous extensional environment.