阿尔泰克兰盆地VMS矿床的变形变质与碳质流体特征  

Deformation, metamorphism and carbonic fluids in VMS deposits of Kelan Basin, Altay

作　　者：徐九华[1] 林龙华[1] 王琳琳[1] 褚海霞[1] 卫晓峰[1] 陈栋梁[2] 

机构地区：[1]北京科技大学资源工程系,北京100083 [2]中国科学院高能物理研究所,北京100049

出　　处：《矿床地质》2009年第5期585-598,共14页Mineral Deposits

基　　金：国家自然科学基金(40672060);北京正负电子对撞机国家实验室课题(vr-08030)的联合资助

摘　　要：阿尔泰南缘克兰火山-沉积盆地的泥盆纪VMS型矿床经历了石炭纪—二叠纪同造山的区域变质和热液叠加改造作用,同构造石英脉和穿切层状铅锌矿化的脉状铜矿化很发育。矿石中反映压力-重结晶作用的各种结构构造发育,包括碎斑结构、交代结构、斑状变晶结构和碎裂结构,以及塑性流动构造或皱纹构造、压力影等。对铁木尔特、大东沟铅锌（铜）矿床的包裹体研究表明,在矿化构造岩和晚期硫化物石英脉中发育极丰富的碳质（CO2-CH4-N2）流体。与碳质流体共生的LCO2-LH2O型包裹体均一温度为243.1~412.1℃（铁木尔特）和209~430℃（大东沟）,碳质流体的捕获压力估计为180~300MPa。这些特征与区域变质的温压条件相当,与VMS无关。同步辐射X射线荧光（SRXRF）单个包裹体的重金属微量元素初步对比分析表明,造山型萨热阔布金矿的碳质流体中检出有Au、As,而在VMS矿床中没有检出,说明碳质流体在区域变质过程中对Au成矿有贡献。The Devonian Kelan volcanic-sedimentary basin, extending along the south margin of the Altay Mountains, hosts many Pb-Zn-Cu and Au deposits in the Kangbutiebao Formation （D1k） that consists of acid volcanic rocks and volcaniclastic and carbonic sedimentary rocks. During Carboniferous and Permian, the Devonian VMS deposits experienced deformation and metamorphism so that sulfide quartz veins paralleling with or cutting schist occur widely. Of these deposits, the Tiemurte Pb-Zn-（Cu） deposit is the largest one. Carbonic（CO2-CH4-N2）fluid inclusions in late sulfide-quartz veins represent a very different younger event not related to VMS ores. Some LCO2-LH2O inclusions associated with carbonic inclusions have th（total） 243.1～412.1℃. The Dadonggou deposit, another typical VMS deposit in the Kelan basin, also occurs in the Kangbutiebao Formation and has the same mineral assemblages as the Tiemurte deposit. Fluid inclusions in the vein quartz of stage II are also dominated by secondary carbonic inclusions and CO2-rich inclusions. CO2-rich inclusions （LCO2-LH2O） occasionally associated with carbonic inclusions have 216～430℃ of th（total）. The estimated trapping pressures of carbonic inclusions are in the range of 180～300 MPa, which correspond to a depth of 6.7～11.1 km according to lithostatic pressures. This depth was impossible for VMS deposits. SRXRF analysis shows that Au is not detected in carbonic fluid inclusions of the Tiemurte VMS deposit but is high in the orogenic Sarekoubu deposit. It is considered that the Sarekoubu deposit had higher Au content than the Tiemurte deposit in volcanic sedimentation in Early Devonian so that the Sarekoubu deposit had original gold enrichment. In Carboniferous gold deposits related to carbonic fluids were formed during orogeny, whereas no economic gold mineralization was superimposed at the Tiemurte deposit except for carbonic fluid overprints.

关 键 词：地球化学 铅锌(铜)矿床 变形变质 碳质流体 SRXRF分析 阿尔泰 

分 类 号：P618.42[天文地球—矿床学] P618.43[天文地球—地质学]