阿尔泰南缘托库孜巴依金矿床流体包裹体特征及成矿流体演化  

Fluid inclusion characteristics and ore-forming fluid evolution of the Tuokuzibayi gold deposit in the southern margin of Altay

作　　者：张敏 牛向龙 莫凌超 牛斯达 吴华英 周起凤 ZHANG Min;NIU XiangLong;MO LingChao;NIU SiDa;WU HuaYing;ZHOU QiFeng(Institute of Mineral Resources,China Metallurgical Geology Bureau,Beijing 100131,China;Mineral Comprehensive Utilization Research and Development Center,China Metallurgical Geology Bureau,Beijing 100131,China)

机构地区：[1]中国冶金地质总局矿产资源研究院,北京100131 [2]中国冶金地质矿物综合利用研发中心,北京100131

出　　处：《岩石学报》2020年第4期1171-1185,共15页Acta Petrologica Sinica

基　　金：中国冶金地质总局科技创新项目(冶金地质科[2016]296号)资助.

摘　　要：新疆西北部的托库孜巴依(巴依)金矿床位于西伯利亚古板块南缘,阿尔泰陆缘活动带克兰弧后盆地与哈巴河弧间盆地接壤处。本次研究在前人成果基础上,通过详细的野外调查、室内显微观察、流体包裹体测温、激光拉曼成分分析和氢-氧同位素分析等多种方法,揭示了巴依金矿各成矿阶段流体特征、成矿热液来源和流体演化过程。根据野外矿脉空间分布、穿插关系、矿物组合及结构构造等特征,结合流体包裹体研究,本文将巴依金矿的成矿作用划分为4个阶段:石英-磁铁矿阶段(Ⅰ),主要发育富液相包裹体,均一温度范围在3529~4134℃区间,盐度范围为73%~147%NaCleqv,平均为104%NaCleqv;石英-黄铁矿阶段(Ⅱ),该阶段主要发育富液相包裹体、富气相包裹体以及含子晶包裹体,均一温度范围为1860~3398℃,盐度变化范围为27%~443%NaCleqv,平均为92%NaCleqv;石英-黄铁矿-黄铜矿阶段(Ⅲ)主要发育富液相包裹体和含(富)CO2三相水溶液包裹体,均一温度范围为1410~1864℃(富液相包裹体),盐度范围较大,介于0~88%NaCleqv之间;石英-方解石阶段(Ⅳ),流体包裹体以富液相为主,均一温度范围1020~1400℃,盐度范围为02%~43%NaCleqv。该矿床从成矿早阶段到成矿晚阶段温度-盐度整体呈下降趋势,在主要成矿阶段(Ⅱ、Ⅲ)出现流体沸腾现象。各成矿阶段δ18O、δD同位素变化范围分别为:成矿早阶段(Ⅰ)531‰和-8510‰;主要成矿阶段(Ⅱ、Ⅲ)-153‰~150‰和-974‰^-811‰;成矿晚阶段(Ⅳ)-352‰^-342‰和-939‰^-871‰,成矿流体主要是早阶段的变质水与中晚阶段加入的大气水混合而成。巴依金矿成矿流体表现为一套中低盐度NaCl-H2O-CO2流体体系,符合造山型金矿成矿流体特征。综合矿床地质研究,本文认为在晚石炭世-二叠纪喀拉通克岛弧与西伯利亚板块碰撞造山构造体制下,流体混合、压力降低和沸腾作用是巴依金矿床富集成矿的�The Tuokuzibayi(Bayi)gold deposit in the northwestern part of Xinjiang is located at the southern margin of the Siberian ancient plate the boundary between the Kelan arc basin and the Haba inter-arc basin in the Altai continental margin.Since its discovery,it has been the subject of many attentions.Based on the previous studies,the detailed field investigations,fluid inclusion temperature measurement,laser Raman composition test,and hydrogen-oxygen isotope analysis have been carried out in our study in order to better understand the ore-forming hydrothermal stage,the source of ore-forming hydrothermal fluids and the genetic type of the deposit.According to the characteristics of field vein interpenetration-mineral combination-spatial distribution and structure,the mineralization of the Bayi gold deposit can be divided into four metallogenetic stages which are quartz-magnetite stage(Ⅰ),quartz-pyrite stage(Ⅱ),quartz-pyrite-chalcopyrite stage(Ⅲ)and quartz-calcite stage(Ⅳ).The primary fluid inclusions of the deposit are mainly of four types:liquid-rich,gas-rich,crystals-included and CO2-contained three-phase aqueous solution inclusion.The uniform temperatures(352.9~413.4℃)and salinities(7.3%~14.7%NaCleqv)were obtained from the inclusions of the quartz pyrite stage.The inclusions from the quartz-pyrite stage have a uniform temperature range of 186.0~339.8℃,and the salinity varies from 2.7%to 44.3%NaCleqv.The uniformity temperature of the ore-forming fluid in the quartz-pyrite-chalcopyrite stage is 141.0~186.4℃,and the salinity is 0~8.8%NaCleqv.The inclusions in the quartz-calcite stage show a uniform temperature range of 102.0~140.0℃coupled with salinity range of 0.2%to 4.3%NaCleqv.Our study shows that the temperature and salinity of the deposit from the early stage of mineralization to the late stage of mineralization display a downward trend,and that the boiling is present in the major metallogenetic stages(ⅡandⅢ).Theδ^18O andδD ranges in different mineralization stages are 5.31‰and-85.10‰i

关 键 词：流体包裹体 H-O同位素 成矿热液 矿化 巴依金矿床 

分 类 号：P618.51[天文地球—矿床学]