兰坪盆地科登涧脉状铜矿床地质、地球化学特征  

Geology and geochemistry of the Kedengjian vein-type copper deposit in western Lanping basin

作　　者：张锦让[1,2] 温汉捷[2] 邹志超[3] 

机构地区：[1]中国地质调查局成都地质调查中心,四川成都610081 [2]中国科学院地球化学研究所,贵州贵阳550002 [3]成都理工大学地球科学学院,四川成都610059

出　　处：《岩石矿物学杂志》2016年第4期692-702,共11页Acta Petrologica et Mineralogica

基　　金：国家青年科学基金资助项目(41403038);中国地质调查局资助项目(121201010000150016-05)~~

摘　　要：兰坪盆地西缘发育一系列脉状铜矿床,科登涧铜矿床是其组成之一。该矿床矿体主要产出于上三叠统崔依比组(T3c)中基性火山岩内部的断层破碎带中。热液期成矿作用可大致划分为2个成矿阶段:主成矿阶段主要发育大量含铜硫化物石英脉,晚成矿阶段主要发育贫硫化物方解石脉。流体包裹体结果表明,主成矿期石英和成矿后期石英/方解石中均主要发育两相水溶液包裹体,含CO2包裹体极少出现。主成矿期石英脉中包裹体均一温度变化幅度较小,集中在180~240℃,盐度(Na Cleq,质量分数)集中在8%~14%。成矿流体主要表现出盆地热卤水的特征,这与兰坪盆地内其它Pb、Zn、Cu等贱金属矿床的成矿流体特征较为一致。成矿流体的δ18O值为3.5‰~5.5‰,δD值为-62‰^-38‰,介于岩浆水/变质水和大气降水之间。热液硫化物黄铜矿、黄铁矿、斑铜矿的δ34S值显示较低的负值(-20.8‰^-9.4‰),明显有别于赋矿围岩(安山岩)的δ34S值(11.1‰~11.6‰),推测该矿床成矿所需还原硫主要来自于地层硫酸盐。综合分析认为,该矿床成矿物质主要来源于地层,成矿流体主要为源于大气降水或建造水的盆地热卤水。A series of sediments-hosted vein-tpye copper deposits have been discovered in the western part of the basin. The Kedengjian vein-type copper deposit is one of these deposits in Lanping basin. The Cu mineralization mainly occurs as sulfide-bearing quartz-carbonate veins in faults and fractures, hosted by volcanic rocks of Triassic Cuiyibi Formation（T3c）. Ore-forming process of the Kedengjian copper deposit can be divided into two stages： the major stage（massive polymetallic sulfide quartz vein stage）, and the late stage（carbonate-quartz stage）. A detailed study of fluid inclusions led to the recognition of two types of fluid inclusions, i.e., aqueous water, and CO2H2O inclusions, with the aqueous water inclusions being dominant. Total homogenization temperatures range from 180℃ to 240℃, with corresponding salinities from 8% to 14% NaCl equivalent. These characteristics of fluid inclusions in the Kedengjian copper deposit are comparable with those of basinal mineralization systems, which formed most Pb-Zn deposits in the Lanping basin. The H, O isotope studies of inclusions in quartz suggest that the ore-bearing fluid was derived from atmospheric water. The δ34S of sulfide minerals are widely variable between -20.8‰ and -9.4‰, indicating that the sulfur was derived from the sedimentary rocks of the basin. Comprehensive studies indicate that the ore-forming materials originated mainly from sedimentary rocks, and the ore-forming fluids were mainly composed of basinal brines, derived from formation water in strata and meteoric water.

关 键 词：地质特征 地球化学 科登涧脉状铜矿床 兰坪盆地 

分 类 号：P597.2[天文地球—地球化学] P618.41[天文地球—地质学]