安徽东溪浅成低温热液型金矿床成矿流体特征和形成时代——流体包裹体和赋矿安山岩U-Pb年代学约束

发布时间：2018-04-28 09:21

  本文选题：锆石U-Pb年龄 + 流体包裹体　； 参考：《岩石矿物学杂志》2017年05期

【摘要】：安徽东溪金矿床位于桐柏-大别造山带北淮阳构造带的中生代晓天火山盆地中,是桐柏-大别成矿带具有代表性的浅成低温热液金矿床。金矿体以含金方解石脉和方解石-石英脉形式产出,受NW向断裂控制,赋矿围岩为毛坦厂组安山质火山岩。该矿床热液成矿过程由早到晚可分为粗晶方解石阶段和方解石-石英阶段。早、晚阶段方解石中流体包裹体十分发育,主要类型有纯液相、纯气相和富液二相流体包裹体。早阶段流体包裹体均一温度范围为128~172℃,冰点温度介于-0.7~+23.4℃之间,盐度为0.35%~0.92%;晚阶段流体包裹体均一温度范围为105~160℃,冰点温度介于-0.5~+9.1℃之间,盐度为0.18%~0.52%。成矿流体从早阶段演化到晚阶段,温度和盐度具有小幅度的降低趋势。岩浆热液和加热循环的大气降水的混合可能是引起金属元素富集、沉淀的主要机制,该矿床是地表浅部热液对流系统的产物。LA-ICP-MS锆石U-Pb同位素研究表明,赋矿安山岩的锆石~(206)Pb/~(238)U加权平均年龄为126.7±1.4Ma(1σ,MSWD=0.95),代表了其火山作用时限。结合矿床地质特征认为,东溪金矿床成矿时间可能与安山岩喷发时限基本一致。该矿床形成于早白垩世陆壳强烈伸展和岩石圈地幔上涌的动力学背景。
[Abstract]:Dongxi gold deposit, located in the Mesozoic Xiaotian volcanic basin of the northern Huaiyang tectonic belt of the Tongbai Dabie orogenic belt, is a typical epithermal hydrothermal gold deposit in the Tongbai Dabie metallogenic belt. The gold orebody is formed in the form of gold-bearing calcite vein and calcite quartz vein, controlled by NW fault, and the host rock is Anshan volcanic rock of Maotanchang formation. The hydrothermal metallogenic process of the deposit can be divided into coarse calcite stage and calcite quartz stage from early to late. The fluid inclusions in the early and late stages of calcite are well developed. The main types of fluid inclusions are pure liquid phase, pure gas phase and liquid rich two-phase fluid inclusions. The homogenization temperature range of fluid inclusions in early stage is 128 ~ 172 鈩，

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