大兴安岭北段争光金矿地质特征及成矿机制研究

发布时间：2018-01-17 16:41

  本文关键词：大兴安岭北段争光金矿地质特征及成矿机制研究　出处：《中国地质大学(北京)》2016年硕士论文　论文类型：学位论文

  更多相关文章： 流体包裹体 C-H-O-He-Ar同位素 黄铁矿微量元素 争光金矿床 大兴安岭

【摘要】：争光浅成低温热液型金矿床位于大兴安岭成矿带北段,是多宝山矿集区内的一个重要矿床。本文对该矿床的地质特征、全岩及微区地球化学、成矿流体、同位素示踪等方面进行了系统研究,取得的主要成果如下:(1)前人研究的锆石LA-ICP-MS U-Pb测年数据表明,争光金矿闪长岩形成于晚侏罗世(151Ma)。本文岩石地球化学特征显示,争光闪长岩属准铝质钙碱性岩石,具有富Fe、Ca、Al和Mg、贫Na和K、富集大离子亲石元素和轻稀土元素、亏损高场强元素和重稀土元素、Eu异常不明显的特点。上述特征表明,争光闪长岩由俯冲流体交代的地幔楔部分熔融形成。(2)流体包裹体研究表明,争光金矿床主要发育富液两相包裹体。流体包裹体均一温度介于116~294℃之间,盐度w(NaCleq)为0.9%~13.8%。石英流体包裹体的δD和δ18O分别为-127‰~-110‰和-5.9‰~0.6‰。方解石的δ13C和δ18O分别为-5.3‰~-2.0‰和7.7‰~13.5‰。黄铁矿流体包裹体的3He/4He、40Ar/36Ar和40Ar*/4He比值分别为1.75~3.06Ra、683~1295和0.30~0.63。流体包裹体和稳定同位素特征显示,成矿早阶段成矿流体为大气降水与围岩发生水-岩反应后的演化水。随着成矿作用的进行,成矿流体变为大气降水与岩浆水的混合水。(3)通过矿相学研究、扫描电镜观察和能谱分析,查明该矿床金矿物种类主要为银金矿、金银矿、自然金和碲金银矿。金的赋存状态为粒间金、裂隙金、包裹金和固溶体金。(4)黄铁矿电子探针和微区原位LA-ICP-MS测试结果显示,该矿床黄铁矿Fe和S的含量变化较小,但是Au、Ag、As、Se、Co、Ni在不同类型黄铁矿中的含量存在差异。黄铁矿的Co/Ni值为0.04~318.36(平均为20),Se含量为0.100~395.3ppm(平均为63),是典型的热液成因黄铁矿。Au未饱和的成矿流体与贫H2S的流体混合是该矿床金沉淀的主要机制。(5)争光金矿床的形成与闪长岩有着密切联系。闪长岩不仅是成矿流体和成矿物质的主要来源,还为成矿流体的对流循环提供了热能。
[Abstract]:The Gengguang epithermal hydrothermal gold deposit is located in the northern section of the Daxinganling metallogenic belt and is an important deposit in the Dobaoshan ore concentration area. This paper deals with the geological characteristics of the deposit, the geochemistry of the whole rock and microregion, and the ore-forming fluid. The main results obtained are as follows: 1) the zircon U-Pb dating data obtained by previous studies show that the zircon U-Pb dating results are as follows. The diorite of Zhengguang gold deposit was formed in the late Jurassic (151Ma). The geochemical characteristics of this paper show that the diorite is a kind of quasi-aluminous calc-alkaline rock, which is rich in Fe ~ (2 +) Ca ~ (2 +) Al and mg. The characteristics of poor Na and K, enrichment of large ion lithophile elements and light rare earth elements, depletion of high field strength elements and heavy rare earth element EU anomalies are not obvious. The study of fluid inclusions from the subducted fluid metasomatic mantle wedge formed by partial melting of the glowing diorite. Liquid rich two-phase inclusions are mainly developed in Zhengguang gold deposit. The homogenization temperature of fluid inclusions is between 116 ~ 294 鈩，

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