豫西萑香洼金矿H-O-S同位素地球化学特征及矿床成因

Geochemical characteristics of H-O-S isotopes and genesis of the Huanxiangwa gold deposit in western Henan

文章在总结矿床基本地质特征基础上,通过对矿石的硫同位素、氢氧同位素组成特征的研究,探讨了成矿物质和成矿流体来源。研究结果表明,该金矿床成矿物质主要来自上地幔,部分来自下地壳,具有以幔源为主的幔壳混合源特征。成矿流体主要来自地幔流体,与陆内俯冲形成的热液和下地壳部分熔融形成的岩浆水混合,在成矿前形成了以地幔流体为主的深源流体。成矿流体中金主要以[Au(HS)_2]^-、[Au H_3Si O_4]~0形式迁移。流体—岩石相互作用(水—岩反应)以及在此过程中的硅化、硫化物形成作用和降温减压作用,是萑香洼金矿床金沉淀的主要机理。萑香洼金矿床的成因与和印支—燕山期碰撞造山、陆内俯冲、伸展作用有关的构造活动密切相关。

Based on summarizing the basic geological characteristics of the deposit,this paper probes further into the sources of ore-forming materials and metallogenic fluids by studying the composition of sulfur,hydrogen and oxygen isotopes.The results show that the ore-forming materials of this gold deposit is mainly from the upper mantle,partly from the lower crust,and has the characteristics of mantle-crust-mixed resource mainly mantle-derived. The metallogenic fluids mainly came from the mantle fluid,which were mixed with hydrothermal fluid formed by the intracontinental subduction and magma water formed by partial melting of the lower crust,forming the deep-sourced fluids mainly composed of mantle fluid before the mineralization. Fluid-rock interaction（ water-rock reaction）,including silicification,sulfurization and lowing temperature and pressure in this process,are the main depositional mechanisms of Au of the Huangxiangwa gold deposit. The genesis of the deposit is closely related to the tectonic activities associated with collision orogenesis,intracontinental subduction and extensional tectonism at Indosinian-Yanshanian period.