黑龙江东宁东风沟金矿床成矿流体特征及矿床成因

东风沟金矿床为产于黑龙江省东宁县老黑山断陷盆地中小型金矿床,成矿与火山活动关系密切,火山岩地层为后期成矿提供部分成矿物质。矿石中金属矿物主要为自形—半自形黄铁矿、他形黄铁矿,且他形黄铁矿与金矿化关系密切。按矿物组构特征,其成矿阶段为自形黄铁矿-石英阶段、他形黄铁矿-石英阶段、石英-方解石阶段。流体包裹体研究表明:主成矿阶段流体主要发育气液二相包裹体,气相成分主要为H2O,CO2和CH4次之,液相成分主要为H2O;成矿流体均一温度为169.8~238.0℃,盐度为4.32%~9.47%,密度为0.88~0.94 g/cm3,属于中低温、中低盐度、低密度流体;经估算成矿压力为14.56~23.04 MPa,成矿深度为1.46~2.30 km,为中浅成深度。综合研究认为,东风沟金矿床为与火山活动关系密切的中浅成中低温热液矿床。

Ore-forming fluid features and genesis of Dongfenggou Gold Deposit in Dongning,Heilongjiang

Dongfenggou Gold Deposit is a medium small-scale gold deposit,located within the Laoheishan rift ba-sin in Dongning County in Heilongjiang.The deposit genesis is closely associated with volcanic activities,and volcanic rock strata provide part of metallogenic materials to the late period of mineralization.The metal minerals are mainly composed of euhedral-subhedral pyrite and allotriomorphic pyrite,of which euhedral pyrite was closely related to gold mineralization.According to mineral structural characteristics, the mineralization can be divided into three stages, namely euhedral pyrite-quartz stage,xenomorphic pyrite-quartz stage,and quartz-calcite stage.The results of fluid in-clusions showed that in major ore-forming stages developed gas-liquid two-phase inclusions.The composition of gas phase is primarily H2 O,and then CH4 and CO2 ,while the liquid phase is mainly H2 O.The homogenization temperature of ore-forming fluids ranges from 169.8 ℃ to 238.0 ℃, salinity varies from 4.32 % to 9.47 %, density from 0.88 g/cm3 to 0.94 g/cm3 .The ore-forming fluid is characterized by medium-low temperature,medium-low salinity and low density.According to estimation,ore-forming pressures range from 14.56 MPa to 23.04 MPa,and ore-forming depth ranges from 1.46 km to 2.30 km,making the deposit a medium-hypabyssal one.Comprehensive research shows that Dongfenggou Gold Deposit belongs to a medium-hypabyssal and medium-epithermal deposit closely related to vol-canic activities.