黑龙江省逊克县坤得气南山金矿床流体包裹体研究

STUDY ON THE FLUID INCLUSION OF THE KUNDEQI NANSHAN GOLD DEPOSIT IN XUNKE COUNTY,HEILONGJIANG PROVINCE

坤得气南山金矿床产出于小兴安岭-张广才岭多金属成矿带北缘,矿体赋存于光华组硅化长石砂岩、细砂岩中.金矿化包括石英-黄铁矿、石英-多金属硫化物和石英-方解石3个成矿阶段.前两个阶段矿石硅化石英细脉中的石英矿物的流体包裹体,包括气液两相包裹体、富气相包裹体和含子矿物三相包裹体3种类型,并以气液两相包裹体为主.流体包裹体的均一温度变化范围在234.8～420.5℃之间,盐度(NaCl当量质量分数)变化在2.6%～33.6%之间,可分为高温低盐度、中高温中低盐度和中高温中高盐度类.流体包裹体气相成分主要为H2O、CO2;液相成分也以H2O、CO2为主,含有Na+、K+、Ca2+、Mg2+离子;子矿物主要为石盐.3类包裹体在同一矿物颗粒中同时共生发育,表明捕获流体为不均匀流体状态,显示成矿过程中存在一定程度的溶体不混溶作用.根据流体包裹体研究结果,确定矿床为浅成热液成因,而且矿床深部具有找寻斑岩型矿化的潜力.

The Kundeqi Nanshan gold deposit occurs in the north of Xiaoxinganling-Zhangguangcailing polymetal metallogenic belt,with orebodies hosted in the silicified arkose and fine sandstone of Cretaceous Guanghua Formation.The gold mineralization covers three stages,involving quartz-pyrite,quartz-polymetal sulfide and quartz-calcite.Research was carried out for the fluid inclusions in quartz from the silicified quartz vein ores of the former two stages,which include gas-liquid two-phase,gas-rich phase and daughter mineral-bearing three-phase,dominated by the gas-liquid two-phase.The homogenous temperature ranges from 234.8 to 420.5 ℃,with salinity（NaCl eq.） between 2.6% and 33.6%,which can be classified into high temperature-low salinity,medium-high temperature-low salinity and medium-high temperature medium-high salinity types.The gas compositions in fluid inclusion are mainly H2O and CO2.The liquid compositions are also dominated by H2O and CO2,with Na＋,K＋,Ca2＋ and Mg2＋ ions.Halite is the major daughter mineral.The three types of inclusions coexist in the same mineral grain,suggesting that the hosting fluid have been in inhomogeneous state,showing certain immiscibility during the ore-forming process.Based on the study result for the fluid inclusion,the deposit is decided to be epithermal genesis,with potentiality for porphyry type of mineralization in the deep.