阿尔泰塔拉特铅锌矿床的变质叠加改造--地质和流体包裹体证据  

Metamorphic overprints on the Talate Pb-Zn deposit in Altay: Evidences from geology and fluid inclusions

作　　者：张辉[1] 徐九华[1] 郭旭吉 肖星[1] 林龙华[1] 杨蕊[1] 成曦晖 

机构地区：[1]北京科技大学资源工程系,北京100083 [2]新疆维吾尔自治区有色地质勘查局七0六队,阿勒泰836500

出　　处：《岩石学报》2015年第4期1063-1078,共16页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(41372096;40972066)资助

摘　　要：塔拉特(阿巴宫)铅锌矿位于阿尔泰克兰火山-沉积盆地南东段,矿床受区域性NW向断裂——克因宫断裂和阿巴宫断裂的控制,Pb-Zn矿体赋存于下泥盆统康布铁堡组下亚组第二岩性段上部(D1k12)的变质岩系中,具明显的层控特征,后期脉状硫化物-石英脉叠加作用明显。根据矿体产出特征可识别出2个明显的成矿期:海相火山沉积喷流成矿期和变质热液叠加成矿期。变质热液期可包括2个阶段,早阶段透镜状石英脉沿含矿层位中绿泥石片岩、浅粒岩等顺层分布,并有浸染状黄铁矿产出;晚阶段含黄铁矿-黄铜矿石英脉穿切绿泥石片岩、浅粒岩或块状铅锌矿石,硫化物稀疏浸染状分布。海相火山沉积喷流成矿期的闪锌矿存在残留的L-V盐水包裹体及后期沿次生裂隙分布的L-V和H2O-CO2包裹体,原生L-V包裹体的均一温度Th,tot=267~334℃,次生H2O-CO2包裹体Tm,CO=-61.2^-60.2℃,T2h,CO=6.5~11.0℃。2变质热液期早阶段石英脉(QI)赋存有大量的H2O-CO2包裹体和较多的碳质流体包裹体(CO2±CH4体系),H2O-CO2包裹体Th,tot=294~368℃,盐度为5.5%~7.4%NaC leqv。碳质流体包裹体的Tm,CO=-60.1^-58.5℃,T.2~20.6℃。2h,CO=-42晚阶段切层含黄铁矿-黄铜矿石英脉中也有大量H2O-CO2包裹体和较多的碳质流体包裹体,H2O-CO2包裹体Th.tot=142~360℃,盐度为2.4%~16.5%NaC leqv。碳质流体包裹体的Tm,CO=-61.5^-57.3℃,T2h,CO0.6℃2有-27.0^-2和27.1~28.7℃两组。次生L-V包裹体的Tm,ice=-9.8^-1.3℃,Th,tot=205~412℃。克兰盆地造山运动过程中形成的区域性富CO2流体,其运移对促进岩(矿)石变形变质以及金属富集产生重要影响。塔拉特铅锌矿床的矿石变形、交代结构及石英脉中富CO2流体的大量出现,说明变质流体参与了叠加改造作用,且具有多阶段的特点。富CO2包裹体形成环境与造山带区域变质晚期或峰期后的P-T演化一致。The Talate Pb-Zn deposit,located on the southeast limb of the Kelan volcanic-sedimentary basin in the Altay,is hosted in the metamorphic rock series of the upper second lithological section of Lower Devonian Lower Kangbutiebao formation（ D1k1^2）,and its disposition and occurrence are controlled by the regional NW fault,the Keyingong fault and the Abagong fault. The Pb-Zn ore bodies occur as stratabound deposit,with the overprints of late sulfide-quartz veins. There were two obvious mineralization periods based on ore occurrences that are submarine volcanic sedimentary exhalation and metamorphic hydrothermal superimposition.Considering mineral assemblages and crosscutting relations of veins,metamorphic overprints could be divided into two stages. In the early stage,bedding lentoid quartz veins distributed in the chlorite schist and the leptite of the ore-bearing horizon. The appearance of disseminated pyritization and the phenomenon that layered sphalerite were replaced by pyrite and chalcopyrite is obvious under the microscope. In the late stage,pyrite-chalcopyrite quartz veins cut chlorite schist and leptite or the massive Pb-Zn ores and sulfides are sparse and disseminated. Fluid inclusions in sphalerite of the submarine volcanic sedimentary exhalation contain residual L-V inclusions,secondary L-V inclusions and a spot of H2O-CO2 inclusions trapped in tiny fissures. Primary L-V inclusions have Th,tot=267 - 334℃,and secondary H2O-CO2 inclusions have Tm,CO2=- 61. 2 -- 60. 2℃ and Th,CO2= 6. 5 - 11. 0℃. The fluid inclusions in early vein quartz of metamorphic period consist of a great number of H2O-CO2 inclusions,carbonic（ CO2± CH4） inclusions and a few H2O-CO2-Na Cl inclusions. H2O-CO2 inclusions are homogenized at the temperature of 294 - 368℃,with salinities of 5. 5% - 7. 4%Na Cleqv. The carbonic inclusions have Tm,CO2of- 60. 1 -- 58. 5 ℃,and Th,CO2of- 4. 2 - 20. 6 ℃. Fluid inclusions in late pyritechalcopyrite quartz veins consist of a great number of H2O-CO2 inclusions,CO2± CH4 inclusions

关 键 词：富CO2流体包裹体 变质热液 叠加改造 塔拉特铅锌矿 克兰盆地 阿尔泰 

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