黔西南紫木凼金矿床成矿物质来源:S-C-O-Pb-Sr同位素制约  

Sources of Ore-Forming Materials of Zimudang Gold Deposit in Southwest Guizhou, China: Constraints from S-C-O-Pb-Sr Isotope Geochemistry

作　　者：蔡应雄 杨红梅[1,2] 卢山松 曾飞[3] 杨文武 刘重芃[1,2] 童喜润 张利国 何波 Cai Yingxiong;Yang Hongmei;Lu Shansong;Zeng Fei;Yang Wenwu;Liu Chongpeng;Tong Xirun;Zhang Liguo;He Bo(Wuhan Center of China Geological Survey,Central South China Innovation Center for Geosciences,Wuhan 430205,China;Research Center of Petrogenesis and Mineralization of Granitoid Rock,China Geological Survey,Wuhan 430205,China;Guizhou Jinxing Gold Mining Industry Co.,Ltd.,Xingren 562300,China)

机构地区：[1]中国地质调查局武汉地质调查中心中南地质科技创新中心,湖北武汉430205 [2]中国地质调查局花岗岩成岩成矿地质研究中心,湖北武汉430205 [3]贵州金兴黄金矿业有限责任公司,贵州兴仁562300

出　　处：《地球科学》2021年第12期4316-4333,共18页Earth Science

基　　金：中国地质调查局地质调查项目(No.DD20160029)。

摘　　要：紫木凼金矿床是黔西南卡林型金矿区一个重要的大型金矿床,其成矿物质来源尚不明确.对紫木凼金矿床不同类型矿石和赋矿围岩进行了S、C、O、Pb和Sr同位素组成对比研究.矿石中硫化物的δ^(34)S值为-13.49‰~17.91‰(主要为-0.99‰~3.58‰),赋矿围岩的δ^(34)S值为-26.23‰~-19.63‰,矿床成矿期硫主要来源于岩浆,部分来源于赋矿地层中成矿前黄铁矿.热液期方解石的δ^(13)C和δ^(18)O分别为-9.10‰~0.59‰和15.65‰~23.82‰,与赋矿围岩、区域地层的碳、氧同位素组成差别较大,成矿流体的碳、氧部分来源于碳酸盐岩溶解,部分可能来源于岩浆.矿石中硫化物的206Pb/204Pb、207Pb/204Pb和208Pb/204Pb比值分别为18.064~18.973、15.585~15.670和38.219~39.054,赋矿围岩的206Pb/204Pb、207Pb/204Pb和208Pb/204Pb比值分别为18.136~18.650、15.574~15.656和38.423~38.812,矿石铅的来源较复杂,赋矿地层和岩浆可能都为其提供了部分铅.矿石中石英和方解石(87Sr/86Sr)i比值为0.70726~0.70811,赋矿围岩的(87Sr/86Sr)i比值为0.70728~0.70731,成矿流体中的锶主要来源于赋矿地层.紫木凼金矿床成矿物质具壳幔混合来源特征,成矿物质主要来自矿床深部隐伏岩浆岩,部分来自二叠系-三叠系赋矿地层.The Zimudang gold deposit,part of the Southwest Guizhou Au metallogenic province,is an important large-size Carlintype Au deposit.However,the sources of ore-forming materials of this deposit are still unclear.In this study,it systematically evaluated the S,C,O,Pb,and Sr isotopic compositions for various orebodies and host rocks of this deposit.δ34S values of sulfides from orebodies range from-13.49‰ to 17.91‰,with peaks ranging from-0.99‰ to 3.58‰,while those of host rocks range from-26.23‰to-19.63‰,which indicates that the sulfur in the ore-forming period mainly derived from magma and partially from pre-mineralization pyrites in the host-strata.δ13C andδ18O values of hydrothermal calcites range from-9.10‰to0.59‰ and 15.65‰ to 23.82‰,respectively,which are different from those of host rocks and regional strata,suggesting that the C and O in ore-forming fluids were partially from carbonate rocks(via dissolution)and might be partially from magma.Pb isotopic ratios of206Pb/204Pb,207Pb/204Pb and208Pb/204Pb for sulfide minerals from orebodies are 18.064 to 18.973,15.585 to 15.670 and38.219 to 39.054,respectively,and those for host rocks are 18.136 to 18.650,15.574 to 15.656 and 38.423 to 38.812,respectively.These Pb isotopic ratios show that the Pb in orebodies was not from a single source,but might be a combination source of host-strata and magma.Initial87Sr/86Sr of quartzes and carbonates from orebodies and the host rocks are in ranges of0.70726-0.70811 and 0.70728-0.70731,respectively,which illustrate that the Sr in ore-forming fluids was mainly from hoststrata.These S,C,O,Pb,and Sr isotopic studies for the Zimudang Au deposit demonstrate that the ore-forming materials have a mantle-crust mixed origin—a main source of deep concealed mantle magma with a minor input from the Permian-Triassic host-strata.

关 键 词：紫木凼金矿 卡林型金矿 黔西南 同位素 成矿物质来源 地球化学 

分 类 号：P597[天文地球—地球化学]