新疆西天山莱历斯高尔斑岩型铜钼矿床辉钼矿Re-Os同位素年龄及流体包裹体研究  

Re-Os isotopic geochronology and fluid inclusion study of the Lailisigao'er porphyry Cu-Mo deposit in western Tianshan,Xinjiang,NW China.

作　　者：朱明田[1,2] 武广[3,4] 解洪晶[1,2] 万阈[5] 钟伟[1] 糜梅[1] 刘军[1,2] 

机构地区：[1]中国科学院广州地球化学研究所成矿动力学重点实验室,广州510640 [2]中国科学院研究生院,北京100049 [3]中国地质科学院矿产资源研究所,北京100037 [4]河南省灵宝市金源矿业有限责任公司,灵宝472500 [5]新疆维吾尔自治区地质矿产勘查开发局第七地质大队,乌苏833000

出　　处：《岩石学报》2010年第12期3667-3682,共16页Acta Petrologica Sinica

基　　金：国家科技支撑计划项目(2007BAB25B03);国家973计划项目(2007CB411303;2007CB411308);国家自然科学基金项目(40772055)联合资助

摘　　要：莱历斯高尔斑岩型铜钼矿床位于依连哈比尔尕晚古生代残余洋盆和博罗霍洛早古生代岛弧的结合部位,矿体赋存于花岗闪长斑岩体内及岩体与围岩的接触带中。矿石中5件辉钼矿的Re-Os同位素模式年龄加权平均值为372.5±5.0Ma、等时线年龄为379.9±8.3Ma,表明莱历斯高尔铜钼矿床形成于晚泥盆世。石英中主要发育气液两相水溶液包裹体(W型)、含CO2三相包裹体(C型)及含子矿物多相包裹体(S型),并有少量纯CO2及纯CH4包裹体。成矿早阶段钾长石化花岗闪长斑岩石英斑晶中主要为W型包裹体,均一温度介于300~395℃之间,峰值为358~395℃,盐度介于7.59%~11.22%NaCleqv;主成矿阶段石英细脉中主要发育W型、C型和S型包裹体,并可见少量纯CO2包裹体,均一温度主要介于230~378℃,盐度变化较大,介于0.02%~52.00%NaCleqv;成矿晚阶段石英-方解石脉中仅见气液两相包裹体,均一温度介于118~241℃之间,盐度主要介于1.57%~9.54%NaCleqv。主成矿阶段流体包裹体类型多样、且具有相似的均一温度,指示流体沸腾现象的存在,其流体包裹体捕获温度为210~343℃,压力为17~59MPa,对应的成矿深度介于1.7~2.2km之间。成矿流体不混溶或沸腾作用是金属硫化物沉淀的主要机制。推测莱历斯高尔斑岩型铜钼矿床形成于晚泥盆世依连哈比尔尕残余洋盆向伊犁-中天山微板块之下俯冲的陆缘弧环境。Lailisigao'er Cu-Mo deposit is located between the Late Paleozoic Yilianhabirga remnant oceanic basin to the north and the Early Paleozoic Bolehelou island arc to the south.The ore bodies are hosted in both granodiorite porphyry and the contact zone between the granodiorite porphyry and its wall rock.Re-Os isotopic ages for five molybdenite samples range from 367±2.0Ma to 378±2.9Ma,with a weighted mean age of 372.5±5.0Ma and an isochronic age of 379.9±8.3Ma,respectively,indicating that the Lailisigao'er Cu-Mo deposit was formed in the Late Devonian.Fluid inclusions in quartz crystals can be classified into aqueous two-phase(W-type),CO2-bearing three-phase(C-type) and daughter mineral-bearing multiphase(S-type) inclusions,as well as minor pure-CO2 and CH4 types.The early stage fluid inclusions in quartz phenocrysts from K-feldspathized granodiorite porphyry are mainly aqueous two-phase inclusions that yield homogenization temperatures of 358℃ to 395℃ and salinities of 7.59% to 11.22% NaCl equivalent,respectively.The ore-forming stage quartz-molybdenite veins in both granodiorite porphyry and hornfels contain aqueous two-phase,CO2-bearing three-phase,daughter mineral-bearing multiphase,and minor pure CO2 fluid inclusions.These fluid inclusions have homogenization temperatures of 230℃ to 378℃ and salinities of 0.02% to 52.00% NaCl equivalent,respectively.Fluid inclusions of the late stage quartz-calcite vein are characterized by aqueous two-phase inclusions,with homogenization temperatures of 118℃ to 241℃ and salinities of 1.57% to 9.54% NaCl equivalent.Fluid boiling in the main stage is evidenced by the co-existence of three types of fluid inclusions with similar homogenization temperatures.Fluid inclusions of main stage were trapped at temperatures of 210~343℃ and pressures of 17~59MPa,respectively,corresponding to depths of 1.7~2.2km.Immiscibility or boiling of ore-forming fluid is the dominant factor for metallic sulfide deposition.The Lailisigao'er deposit was likely formed in a late Devonian

关 键 词：辉钼矿RE-OS定年 流体包裹体 斑岩型铜钼矿床 莱历斯高尔 西天山 

分 类 号：P618.41[天文地球—矿床学]