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黔西南灰家堡金矿田成矿流体来源及演化：流体包裹体和稳定同位素证据

ISSN号：1007-2802
期刊名称：《矿物岩石地球化学通报》
时间：0
分类：P618.5[天文地球—矿床学;天文地球—地质学] P597[天文地球—地球化学;天文地球—地质学]
作者机构：[1]中国地质大学(北京)地质过程与矿产资源国家重点实验室,北京100083
相关基金：国家自然科学基金项目（40930423）;国家科技支撑计划项目（2011BAB06B02-02）;国家重点基础研究发展计划（2009CB421003-01）;长江学者和创新团队发展计划项目;高等学校学科创新引智计划（B07011）致谢：野外工作中得到成都理工大学李保华教授、董树义副教授、陈翠华副教授和程文斌讲师的悉心指导,中国科学院地球的研究所夏勇研究员的大力支持和帮助,在此一并表示衷心感谢!

作者：彭义伟[1], 顾雪祥[1], 章永梅[1], 刘丽[1], 吴程赟[1], 陈思尧[1]

关键词：成矿流体, 流体不混溶作用, 流体包裹体, 稳定同位素, 灰家堡金矿田, 黔西南, ore-forming fluid, fluidimmiscibility, fluid inclusions, stable isotopes, Huijiabao gold field, Southwestern Guizhou Province

中文摘要：

为厘清滇黔桂地区卡林型金矿床成矿流体的特征,本文以灰家堡金矿田为代表,对太平洞、紫木凼、水银洞和簸箕田4个典型矿床中热液矿物的流体包裹体进行了系统研究,并对热液矿物进行了碳、氢、氧、硫同位素的分析测试.结果表明,灰家堡金矿田流体包裹体类型丰富,包括NaCl-H2O溶液包裹体、CO2包裹体、CO2-H2O包裹体、烃-H2O包裹体和烃类包裹体五大类.从成矿早阶段到晚阶段,成矿流体组分大致经历了从H2O＋NaCl→ H2O＋NaCl＋ CO2＋ CH4±N2→H2O＋NaCl±CH4±CO2的演化,均一温度和盐度略有降低.流体包裹体及稳定同位素组成特征显示,成矿流体属于富含金属和碳氢化合物的盆地流体;沉积黄铁矿的硫主要来源于封闭海洋盆地中硫酸盐的细菌还原硫;热液硫化物与沉积黄铁矿的硫同位素特征相似,表明成矿流体中的硫来源于成岩黄铁矿的溶解作用,同时有机质热分解和硫酸盐有机质热还原作用亦提供了部分硫.成矿主阶段发生的H2O-NaCl-CO2流体不混溶作用是导致Au沉淀富集的重要机制.

英文摘要：

To provide insights into the ore-forming fluids characteristics of Carlin-type gold deposits in the Southwestern Guizhou Province,the systematic fluid inclusion investigations and C,H,O and S stable isotope analyses have been carried out on the hydrothermal minerals in four typical gold deposits from the Huijiabao gold field,including Taipingdong,Zimudang,Shuiyindong and Bojitian gold deposits.Five types of fluid inclusion are recognized,including aqueous inclusion,mono-phase CO2 inclusion,CO2-H2O inclusion,hydrocarbon-H2 O inclusion and hydrocarbon inclusion.From the early to late stage,the compositions of ore forming fluids experienced the evolution of H2O＋NaCl→H2O＋NaCl＋CO2 ＋CH4 ±N2→H2O＋NaCl±CH4 ±CO2 with a slight decrease in homogenization temperature and salinity.The nature of fluid inclusions and stable isotopes indicate that the ore-forming fluids were composed mainly of ore-and hydrocarbon-bearing basin fluid.The sulfur dynamic fractionation of diagenetic pyrite was controlled by bacterial reduction of marine sulfates.The sulfur isotope compositions of hydrothermal sulfides are very similar to those of diagenetic pyrite in the host rocks,suggesting that the sulfur in the ore-forming fluids was mainly derived from the dissolution of diagenetic pyrite.The immiscibility of H2O-NaCl-CO2 fluids took place during the main mineralization stage and caused the precipitation and the enrichment of gold.

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