阿尔泰铁木尔特铅锌矿床的碳质流体组合及其地质意义  

Carbonic fluid inclusion assemblages and their geological significance at the Tiemurte lead-zinc deposit,Altay.

作　　者：徐九华[1] 单立华[1] 丁汝福[2] Craig J HART 王琳琳[1] 卫晓锋[1] 

机构地区：[1]北京科技大学资源工程系,北京100083 [2]北京矿产地质研究院,北京100012 [3]Dept.of Geology and Geophysics,University of West Australia

出　　处：《岩石学报》2008年第9期2094-2104,共11页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(40672060);国家科技支撑计划(新疆305项目)资助

摘　　要：铁木尔特铅锌矿是阿尔泰克兰盆地内最主要的 VMS 型矿床。矿床受控于阿巴宫—库尔提断裂,铅锌矿体分布于该断裂 NE 逆冲盘的下泥盆统康布铁堡组地层绿泥石英片岩、大理岩或层状矽卡岩中。矿体形态多呈透镜状、似层状,并整合产于变质岩系中,发育多个矿化层。金属矿物有方铅矿、闪锌矿、黄铜矿、黄铁矿和磁黄铁矿等。铁木尔特铅锌矿床晚期发育多金属硫化物石英脉,至少可识别出3个流体包裹体组合(FIA)。FI0为高盐度流体包裹体组合,主要为含子矿物的多相包裹体(L-V-S 型),部分为气液两相包裹体(L-V 型),局限于单个石英颗粒内,包裹体呈无序分布,或呈孤立的单个包裹体分布, 包裹体的最终均一温度322～422.5℃。FI1为次生的CO_2-H_2O 流体包裹体组合,主要由单相(L_(CO_2))和两相(L_(CO_2)-L_(H_2O))的富CO_2包裹体组成,呈线性分布,穿透石英颗粒边界,明显属于次生包裹体范畴、FI2为碳质(CO_2-CH_4)流体包裹体组合,广泛发育,包裹体主要由单相(L_(CO_2)、L_(CO_2-CH_4)或 L_(CO_2-N_2))、少量两相(LCO,-LH'O)富CO。包裹体组成,大小5μm～20μm,成群定向分布,穿透石英颗粒边界并切断 FI1,是晚于 FI1的次生包裹体组合,反映晚期较大的构造—流体活动。对 FI2的详细研究表明,L_(CO_2)型包裹体的 T_(mCO_2)=-63.3～-57.7℃,T_(hCO_2)=-27.5～+29.7℃;L_(CO_2-CH_4)型或 L_(CO_2-N_2)型包裹体的 T_(mCO_2)=-80.5～-65.5℃,T_(hCO_2)=-56.0～-25.0℃;L_(CO_2)-L_(H_2O)型包裹体 CO_2相的 T_(mCO_2)=-66.9～-60.9℃,T_(hCO_2)=-13.3～+2.3℃,包裹体的最终均一温度 T_(h,total)=243.1～361.1℃。铁木尔特次生碳质流体组合,萨热阔布金矿主成矿阶段、赛都—多拉纳含金剪切带中早期透镜状石英脉碳质流体组合,以及阿舍勒等矿床的次生碳质流体组合,都具有相似的流体性质,均为高密度的CO_2-CH_2-N_2流体,其来源与石炭—二叠造山作用主期的区域动力�The Tiemurte deposit, located on the northeast limb of the Devonian Kelang vocanic-sedmentary basin in the Altay, and on the northeast hanging wall of the regional Abagong-Kurti Fault which marks the boundary between the Kangbutiebao （ D1 k） of Lower Devonian age and the Ahai Formation （D2a） of Middle Devonian age, occur in the Kangbutiebao Formation which consists of acid volcanic rocks and volcaniclastic and carbonic sedimentary rocks. The ore bodies, controlled by the second lithological unit of upper Kangbutiebao Formation, occur in chloritized metamorphic siltstone and garnet chloritized marble. The ore minerals are mainly galena, sphalerite, chalcopyrite, pyrite and pyrrhotite, and the gangue minerals are dominated by quartz, actinolite, tremolite, chlorite, barite and carbonate. Three fluid inclusion assemblages （FIA） can be identified in vein quartz. The first FIA （FI0） consists of high salinity inclusions composed of L-V-S inclusions （ containing daughter crystals of NaCl） and L-V inclusions that are distributed in an isolated or random fasion within single quartz grain, with the final homogenization temperatures （ Th,total ） = 322 -422. 5℃. The second FIA （FI1） is a secondary CO2-H2O fluid inclusion assemblage and is composed of 1μm -5μm LCO2 and LCO2-LH2O inclusions. The third FIA （FI2） is a carbonic（ CO2-CH4 ）fluid inclusion assemblage which is composed of liquid CO2 or CO2-CH4 inclusions with minor LCO2- LH2O inclusions. They occur widely in vein quartz, distributed as oriented healed fractures, and usually cut across the boundaries of the quartz grains and truncate the FI1 fluid inclusions, and consequently represent a fluid inclusion assemblage from a later tectonic- hydrothermal event. The melting temperatures of solid CO2 （ Tm CO2 ） range from - 63.3 to - 57.7℃ and Th CO2 = - 27.5 - ＋ 29.7℃, while Tm CO2 of the carbonic inclusions（CO2-CH4） ranges from - 80. 5 to - 65.5℃ and Th CO2 = - 56. 0 - - 25. 0℃. Some LCO2-LH2O inclusions in FI2 have

关 键 词：碳质流体包裹体 铁木尔特矿床 阿尔泰 

分 类 号：P618.4[天文地球—矿床学]