云南中甸红山矽卡岩铜多金属矿床包裹体特征及其地质意义  

Geochemical Characteristics and Their Geological Significances of Ore-forming Fluids at Hongshan Skarn Copper Polymetallic Deposit in the Zhongdian area,Yunnan Province

作　　者：秦朝建[1] 冷成彪 张兴春[1] 王守旭[3] QIN Chao-jian;LENG Cheng-biao;ZHANG Xing-chun;WANG Shou-xu(State Key Laboratory of Ore Deposit Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,China;State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China;Shandong Gold Group Co.,LTD.,Jinan 250014,China)

机构地区：[1]中国科学院地球化学研究所矿床地球化学国家重点实验室,贵州贵阳550081 [2]东华理工大学核资源与环境国家重点实验室,江西南昌330013 [3]山东黄金集团有限公司,山东济南250014

出　　处：《东华理工大学学报（自然科学版）》2021年第5期401-411,共11页Journal of East China University of Technology(Natural Science)

基　　金：国家自然科学基金项目(92062101,42022021);矿床地球化学国家重点实验室开放基金项目(201808)。

摘　　要：通过显微测温和激光拉曼光谱学研究,发现滇西北红山矽卡岩铜多金属矿床的石榴子石、透辉石和斜长石中普遍发育熔体-流体包裹体、含子晶包裹体和气液包裹体。实测熔体-流体包裹体的均一温度为720~1 080℃,说明红山矽卡岩体可能由岩浆直接冷却结晶而成。结合矿床地质特征,推测矽卡质岩浆为中酸性岩浆局部同熔碳酸盐围岩所产生的次生岩浆。熔体-流体包裹体指示了岩浆出溶成矿流体的相分离过程。包裹体中的子晶矿物组合相似,主要为方解石、石盐、钾盐、锰铝榴石、透辉石、杂卤石、赤铁矿及金属硫化物等。成矿流体形成后基本停留在原地,与已固化的石榴子矽卡岩处于相对封闭的构造空间内。当热液系统由于流体内压增大或构造活动破裂,成矿作用进入石英-硫化物期。含矿石英脉捕获了大量的含CO_(2)包裹体和气液两相包裹体,其中含CO_(2)包裹体的盐度一般低于5%NaCl_(equiv.),气液两相包裹体的盐度一般大于18%NaCl_(equiv.)。包裹体均一温度-盐度图解表明,低盐度富CO_(2)流体与中等盐度流体发生的相分离作用,可能是导致石英-硫化物期铜铁硫化物沉淀成矿的主要原因。Based on a combined study of microthermometry and laser Raman spectroscopy,three types of fluid inclusions(i.e.,melt-fluid inclusion,daughter mineral-bearing fluid inclusion and aqueous fluid inclusion)are recognized from garnet,diopside and plagioclase at Hongshan skarn copper polymetallic deposit in the northwestern Yunnan.The homogenization temperature of melt-fluid inclusions is between 720℃and 1080℃,suggesting these minerals were probably formed from skarnic magmas.In combination with the geological characteristics of the deposit,it is speculated that the skarnic magma was a result of interaction and hybridization between the felsic-intermediate magmas and the surrounding carbonate rocks.The presence of numerous melt-fluid inclusions at Hongshan indicates ore-forming fluids were directly derived from the magmas.The daughter mineral-bearing fluid inclusions generally contain similar mineral assemblage,which includes calcite,halite,potash,spessartine,diopside,polyhalite,hematite,and metal sulfides,etc.The ore-forming fluids were likely confined within a closed skarn system after dissolving from the magmas.When the internal pressure of fluid exceeds the hydrostatic pressure of the skarn system,many fractures would form in the host rocks of the system and trigged the precipitation of sulfides in forms of various quartz veins or veinlets.Ore-bearing veins captured a large number of CO_(2)-bearing fluid inclusions and aqueous fluid inclusions.The salinity of CO_(2)-bearing fluid is generally less than 5%NaCl_(equiv.),while the salinity of aqueous fluid inclusions is generally greater than 18%NaCl_(equiv.).The similar homogenization temperature together with different salinities between these fluid inclusions indicates that the phase separation was the main reason for the precipitation of sulfide-quartz veins at Hongshan.

关 键 词：熔体流体包裹体 含CO_(2)包裹体 矽卡岩矿床 滇西北 红山 

分 类 号：P618.41[天文地球—矿床学]