东天山小热泉子铜锌矿床伴生硒富集机制  

Se Enrichment Mechanism of the Xiaorequanzi Copper-zinc Deposit in East Tianshan,China

作　　者：陈浩男 邓小华 何西恒 阿卜力米提·艾白 CHEN Hao-nan;DENG Xiao-hua;HE Xi-heng;ABULIMITI Aibai(School of Earth Science and Resources,Chang'an University,Xi'an 710054,Shaanxi,China;Xinjiang Research Center for Mineral Resources,Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences,Urumqi 830011,Xinjiang,China)

机构地区：[1]长安大学地球科学与资源学院,陕西西安710054 [2]中国科学院新疆生态与地理研究所新疆矿产资源研究中心,新疆乌鲁木齐830011

出　　处：《地球科学与环境学报》2024年第3期384-399,共16页Journal of Earth Sciences and Environment

基　　金：国家自然科学基金项目(42222205,42302108);第三次新疆综合科学考察项目(2022xjkk1301);新疆维吾尔自治区重点研发专项项目(2023B03015)。

摘　　要：小热泉子矿床位于东天山大南湖—头苏泉岛弧带西段,是赋存于石炭纪火山-沉积建造中的火山块状硫化物(VMS)矿床。小热泉子矿床伴生硒等关键金属,但硒赋存状态及富集机制研究较为薄弱,制约了硒的综合利用。在矿床地质特征研究基础上,对不同成矿期次的矿石中硫化物开展全自动综合矿物分析、电子探针成分分析,探索小热泉子矿床中硒赋存状态和富集机制。结果表明:小热泉子矿床中硒主要呈硒独立矿物硒方铅矿或赋存于硫化物的晶格中。硒方铅矿呈半自形—他形产出,粒径多小于30μm,包裹于喷流沉积期和热液叠加期的黄铜矿中,其Se含量(质量分数,下同)为20.25%~23.87%,平均值为22.15%,S含量为1.11%~2.61%,平均值为1.92%,Pb含量为72.49%~76.57%,平均值为74.51%,平均化学式为Pb(Se_(0.78)S_(0.17)),S/Se值为0.087。不同期次黄铁矿、黄铜矿、闪锌矿等硫化物中的Se含量分别为0.07%、0.15%和0.29%,S/Se平均值分别为716、222和110。其中,喷流沉积期硫化物的Se平均含量为0.20%,S/Se平均值为212,热液叠加期硫化物的Se平均含量为0.05%,S/Se平均值为938,显示Se含量具有下降趋势。结合前人流体包裹体研究结果,小热泉子矿床中硒富集机制归因于较高温、较高氧逸度的岩浆流体环境,硒富集伴随成矿系统温度和氧逸度的降低而减弱。The Xiaorequanzi deposit is a volcanic massive sulfide(VMS)deposit that occurred in Carboniferous volcano-sedimentary sequence,which is located in the western section of Dananhu-Tousuquan arc belt,East Tianshan.Critical metals such as Se are associated with Xiaorequanzi VMS deposit.However,Se occurrence status and enrichment mechanism are ambiguous,which restricts the comprehensive utilization of Se.Based on previous research on the geological characteristics of ore deposits,the automated integrated mineral analysis and electron probe micro-analysis on sulfides in different mineralization stages of ore were used to explore Se occurrence status and enrichment mechanism in the Xiaorequanzi deposit.The results show that Se occurs as independent mineral,namely clausthalite,or exists in the lattice of sulfide.Clausthalite occurs in a subhedral to anhedral shape with particle size less than 30μm,which is encapsulated in chalcopyrite of exhalative sedimentary period and late hydrothermal overprinting period.The Se,S,and Pb contents of clausthalite are 20.25%-23.87%,1.11%-2.61%,and 72.49%-76.57%,with an average of 22.15%,1.92%,and 74.51%.The average S/Se ratio is 0.087,and the average chemical formula of clausthalite is Pb(Se_(0.78)S_(0.17)).The Se contents of pyrite,chalcopyrite,and sphalerite are 0.07%,0.15%and 0.29%,and the average S/Se ratios are 716,222 and 110.The average content of Se and S/Se ratio of sulfide in effusive deposit period are 0.20%and 212.The average content of Se and S/Se ratio of sulfide in the late hydrothermal overprinting period are 0.05%and 938,which show a decreasing trend of Se content.Combined with the results of previous fluid inclusion studies,Se enrichment mechanism in the Xiaorequanzi deposit is attributed to the magmatic fluid with higher temperature and higher oxygen fugacity,while Se mineralization weakens followed by the decreasing of oxygen fugacity and temperature.

关 键 词：关键金属 硒 火山块状硫化物矿床 铜锌矿 赋存状态 富集机制 东天山 

分 类 号：P611[天文地球—矿床学]