安徽庐枞矿集区东顾山钨矿床成矿流体来源与演化:来自H、O、S同位素和流体包裹体的证据  

Study of fluid inclusions and H-O-S isotopic compositions of Donggushan tungsten skarn deposit,Anhui Province,China

作　　者：聂利青 周涛发[1,2] 汪方跃 张千明[4] 张明 汪龙虎[4] NIE LiQing;ZHOU TaoFa;WANG FangYue;ZHANG QianMing;ZHANG Ming;WANG LongHu(School of Resources and Environmental Engineering,Ore Deposit and Exploration Centre(ODEC),Hefei University of Technology,Hefei 230009,China;Anhui Province Engineering Research Center for Mineral Resources and Mine Environments,Hefei 230009,China;School of Civil Engineering,Anhui Jianzhu University,Hefei 230601,China;No.327 Geological Party,Anhui Bureau of Geology and Mineral Exploration,Hefei 230011,China)

机构地区：[1]合肥工业大学资源与环境工程学院,合肥工业大学矿床成因与勘查技术研究中心(ODEC),合肥230009 [2]安徽省矿产资源与矿山环境工程技术研究中心,合肥230009 [3]安徽建筑大学土木工程学院,合肥230601 [4]安徽省地质矿产勘查局327地质队,合肥230011

出　　处：《岩石学报》2019年第12期3825-3837,共13页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(41872081、41672081);国家重点研发计划项目(2016YFC0600206);中央高校基本科研业务费专项资金(PA2019GDZC0093)联合资助

摘　　要：长江中下游成矿带是我国重要的铁铜金等金属成矿带,庐枞矿集区中新勘探发现的东顾山矿床与成矿带内燕山期铁、铜大规模成矿作用不同,矿化以钨为主,且已达大型规模。前人已对该矿床开展了基础地质特征和成岩成矿年代学工作,但该矿床的成矿流体和来源特征仍不清楚,矿床成因的确定需要开展相关研究。本文在详细的野外调查基础上,对各成矿阶段流体包裹体及H、O、S同位素进行了系统测定及分析,并结合地质事实,确定了成矿流体特征和来源,为成矿带内钨矿床的成因认识和下一步找矿提供理论依据。流体包裹体研究表明,东顾山矿床流体包裹体类型以纯液相包裹体(L)和气液两相包裹体(V+L)为主,矽卡岩阶段(Ⅰ)的包裹体均一温度集中变化于351~397℃,盐度变化于10. 87%~13. 60%NaCleqv;氧化物阶段(Ⅱ)的包裹体均一温度集中变化于283~367℃,盐度变化于7. 73%~10. 62%NaCleqv;第三阶段石英-硫化物阶段(Ⅲ)的包裹体均一温度变化于180~284℃,盐度变化于4. 08%~7. 57%NaCleqv。从Ⅰ阶段到Ⅲ阶段,均一温度和盐度均有降低的趋势,显示流体混合的特征,可能是其矿质沉淀的重要机制。H-O同位素分析结果(δ18OH2O值为-0. 37‰~2. 79‰,δD值为-60. 56‰^-46. 16‰)显示成矿流体主要为岩浆流体,并有约40%大气降水的加入。硫化物S同位素研究显示,黄铁矿δ34S值范围为4. 39‰~6. 00‰,高于幔源硫,略低于赋矿地层硫值(7. 60‰~8. 13‰),指示东顾山钨矿床硫源为地层硫和岩浆硫混合,地层硫的贡献不容忽视。综合矿床地质、流体包裹体及H、O、S同位素特征可知,东顾山矿床热液成矿过程中发生了显著的流体混合作用,破坏了钨络合物的稳定性,使得大量钨等金属离子从络合物载体中脱离出来并与Ca2+相结合,最终钨酸钙沉淀成矿。通过与成矿带铜铁矿床的成矿流体对比可知,长江中下游成矿带内钨矿�The Middle-Lower Reaches of Yangtze Metallogenic Belt( MLYB) is one of the most important Fe-Cu-Au-polymetallic metallogenic belts in eastern China. The Donggushan deposit was different from the other Fe-Cu-Au deposits in MLYB because of tungsten mineralization. The previous research mainly worked on ore deposit geology and geochronology,but the study on source and characteristic of ore-forming fluid are poor. Based on petrographic observations,primary inclusions of the Donggushan deposit primarily belong to two types: two-phase liquid-vapor and liquid-only fluid inclusions. Fluid inclusions occurred in the skarn stage( Ⅰ) show homogenization temperatures of 351 ~ 397℃ and salinities of 10. 87% ~ 13. 60% NaCleqv. Fluid inclusions occurred in the oxide stage( Ⅱ) of main ore-forming stage show homogenization temperatures of 283 ~ 367℃ and salinities of 7. 73% ~ 10. 62% NaCleqv. Fluid inclusions occurred in the quartz-sulfide phase( Ⅲ) show homogenization temperatures of 137 ~ 314℃ and salinities of 4. 08% ~7. 57% NaCleqv. From the first( Ⅰ) to the third( Ⅲ) stage,the homogenization temperatures and salinities of the fluid inclusions all had a reduced tendency,showing the characteristics of fluid mixing,which may be the mechanism of the precipitation of ore-forming metals. Hydrogen and oxygen isotopic results( δ18OSMOW:-0. 37‰ ~ 2. 79‰,δD:-60. 56‰ ^-46. 16‰) indicate that magmatic fluids and meteoric water were mixed and reached to 40%. The δ34S values of sulfides vary from 4. 39‰ to 6. 00‰,which indicate that sulfur of the sulfide stem from the magmatic source with parts of contribution from the ore-bearing strata sulfide. According to the fluid inclusions and isotope compositions,the ore-forming fluid was formed by mixing of magma water and meteoric water. Fluid mixing is the main ore-forming mechanism of tungsten mineralization in the Donggushan deposit. By comparing with copper and iron deposits fluid characteristics in MLYB,we interpreted that the temperature and salinity are simi

关 键 词：流体包裹体 氢-氧-硫同位素 矽卡岩矿床 东顾山钨矿床 长江中下游成矿带 

分 类 号：P597.2[天文地球—地球化学] P618.67[天文地球—地质学]