西藏拿若铜(金)矿床硫、铅同位素组成及成矿物质来源  

Sulfur and lead isotope composition and tracing for sources of ore-forming materials in the Naruo Cu(Au) deposit,in Tibet

作　　者：高轲 宋扬[2] 刘治博[2] 杨欢欢[2] 王艺云[1] GAO Ke;SONG Yang;LIU Zhibo;YANG Huanhuan;WANG Yiyun(Chengdu Center,China Geological Survey,Chengdu 610081,China;Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China)

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]中国地质科学院矿产资源研究所,北京100037

出　　处：《沉积与特提斯地质》2023年第1期145-155,共11页Sedimentary Geology and Tethyan Geology

基　　金：国家自然科学基金(41702080);中国地质调查局项目(DD20190167,DD20190147);国家重点研发计划深地资源开采项目(2018YFC0604103)联合资助。

摘　　要：为探讨多龙矿集区拿若铜(金)矿床的成矿物质来源,研究矿床成矿机制,本文在详细的野外地质调查和矿石学研究基础上对矿石样品进行硫和铅同位素分析,并对成因意义进行讨论。研究结果表明,17件金属硫化物的δ^(34)S值变化于-2.3‰~2.3‰之间,均值为-0.1‰;其中13件黄铁矿δ^(34)S值变化范围为-2.3‰~2.3‰,均值为0.2‰;4件黄铜矿的δ^(34)S值变化范围为-1.5~-0.8‰,均值为-1.1‰。δ^(34)S值频率直方图总体具有塔式分布特征,平均值接近于零,具幔源硫特征。金属硫化物的^(208)Pb/^(204)Pb介于38.209~38.854之间,平均值为38.635;^(207)Pb/^(204)Pb变化范围为15.541~15.665,平均值为15.605;^(206)Pb/^(204)b为17.942~18.580,平均值为18.461,具有正常铅的特征。铅同位素μ值变化范围为9.40~9.57,均小于9.58,表明矿床铅主要来自幔源物质。拿若矿床的硫和铅同位素特征与多龙矿集区斑岩型矿床类似,成矿物质主要来源于岛弧环境下幔源物质,可能存在壳源物质的混入。On the basis of detailed field geological survey and mineralogical research,in order to discuss the source of ore-forming materials from the Naruo copper(gold) deposit in the Duolong ore-concentrated area and study the metallogenic mechanism,we analyzed the sulfur and lead isotope from the orebody,discussed the significance.The results show that the δ^(34)S values of the seventeen metal sulfides vary from -2.3‰ to 2.3‰,with an average of 0.13‰.The δ^(34)S values of thirteen pieces of pyrite vary from-2.3‰ to 2.3‰,with an average of 0.17‰.δ^(34)S values of four pieces of chalcopyrite vary from-1.5‰ to 0.8‰,with an average of-1.1‰.The δ^(34)S histogram is distributed approximately in a tower shape,with an average nearly zero,which indicates a mantle source.^(208)Pb/^(204)Pb,^(207)Pb/^(204)Pb,^(206)Pb/^(204)Pb isotopic composition of metal sulfides respectively are 38.209~38.854,15.541~15.665 and17.942~18.58,with average of 38.635,15.605 and 18.641.These data show the normal lead characteristics.Lead isotope μ values range from 9.40 to 9.57,less than 9.58.The feature shows that lead mainly comes from mantle material.Sulfur and lead isotopic characteristics of theNaruo deposit are identical with those of other porphyry deposits in the Duolong ore-concentrated area.The oreforming materials of theNaruo deposit was mainly derived from mantle materials in an island arc environment,and there may be a mix of shell-derived materials.

关 键 词：硫同位素 铅同位素 成矿物质来源 拿若铜(金)矿 班怒成矿带 

分 类 号：P618.41[天文地球—矿床学]