滇东南文山州小洞锑矿床成因:来自硅质岩、辉锑矿元素及硫同位素的证据  

Genesis of the Xiaodong Sb deposit,Wenshan Prefecture,southeast Yunnan:Constraints from geochemistry and S isotopes in siliceous rock and stibnite

作　　者：林心怡 林木森 吴久芳 易友根 徐楷 徐净 LIN Xinyi;LIN Musen;WU Jiufang;YI Yougen;XU Kai;XU Jing(Zijin School of Geology and Mining,Fuzhou University,Fuzhou 350108,China;The Western Geological Party of Fujian,Xiamen 361000,China)

机构地区：[1]福州大学紫金地质与矿业学院,福州350108 [2]福建省闽西地质大队,福建厦门361000

出　　处：《成都理工大学学报(自然科学版)》2025年第2期270-284,I0006-I0008,共18页Journal of Chengdu University of Technology: Science & Technology Edition

基　　金：国家自然科学基金重点项目(42230807);福建省教育厅2021年度中青年教师教育科研项目(JAT210031)。

摘　　要：云南文山州小洞锑矿床处于滇东南锑矿带,矿体赋存于寒武系中统田蓬组下段硅质岩中。前人认为其属于变质改造的热水沉积型锑矿床,但关于该矿床的成岩成矿机制和矿床成因类型等问题仍有争议。对赋矿围岩硅质岩的主微量分析显示,w(SiO_(2))为84.70%~97.11%(均值92.19%),w(Al_(2)O_(3))为0.63%~6.08%(均值3.56%),ΣREE为(20.43~77.54)×10^(−6),稀土配分曲线右倾,δEu值为0.66~1.57(均值0.88),δCe值为0.95~1.15(均值1.07),形成于大陆边缘的非热水沉积环境,成分受陆源输入的控制。辉锑矿LA-ICP-MS分析揭示了其微量元素的主要耦合替代机制为2Sb^(3+)↔As^(3+)+(Cu^(+)+Pb^(2+))。辉锑矿的S同位素分析显示δ^(34)S值变化范围较窄(0.42‰~4.91‰),暗示成矿物质来源于岩浆,成矿热液可能与老君山岩体活动相关,或者为深部隐伏岩体带来的热液。综合分析认为,小洞锑矿床的赋矿围岩与热水沉积无关,成矿物质主要来源于岩浆热液。岩浆活动后期的含矿热液流体沿断裂带运移,在层间虚脱带富集成矿,属于受断裂控制的热液型锑矿床。The Xiaodong Sb deposit in Wenshan Prefecture,Yunnan Province,is located in the southeastern Yunnan Sb metallogenic belt.The Sb ore body is present in siliceous rocks located in the lower section of the Tianpeng Formation,Middle Cambrian.Although previous studies proposed that it is a hydrothermal sedimentary Sb deposit formed via metamorphism,its petrogenesis and metallogenic mechanisms still remain unclear.This study performs major and trace element analysis of the siliceous rocks,and the results show w(SiO_(2))content of 84.70%~97.11%(average of 92.19%),while the w(Al_(2)O_(3))has a content of 0.63%~6.08%(average of 3.56%).ΣREE ranges from 20.43×10^(−6) to 77.54×10^(−6),showing an enrichment of LREE and a depletion of HREE,with δEu(0.66~1.57)andδCe(0.95~1.15).The results reveal that the siliceous rocks formed by non-hydrothermal sedimentation in the continental margin and they originated in terrestrial sources.An LA-ICP-MS analysis of trace elements in the stibnite shows that the main substitution mechanism is 2Sb^(3+)↔As^(3+)+(Cu^(+)+Pb^(2+)).The δ^(34)S value of stibnite(0.42‰ to 4.91‰)shows the signature of magmatic sulfur,implying that the mineralized hydrothermal fluids maybe related to the Laojunshan intrusion or deep,hidden magmatic rocks.The comprehensive analysis presented here shows that the Xiaodong deposit is not related to hydrothermal sedimentation;instead,the mineralized material mainly came from magmatic hydrothermal fluid,which enriched the interlayer fracture belt during a late stage of magmatic activity.This study characterizes the deposit as a fault-controlled hydrothermal Sb deposit.

关 键 词：硅质岩 辉锑矿 硫同位素 矿床成因 滇东南 

分 类 号：P611[天文地球—矿床学] P595[天文地球—地质学]