黑龙江省羊鼻山铁钨矿床中钨矿成因及物质来源

Genesis and Material Source of Scheelite of Yangbishan Iron-Tungsten Deposit in Heilongjiang,NE China

黑龙江省双鸭山市羊鼻山铁钨矿床处于中亚造山带东段的佳木斯地块中部。兴东群大盘道组变质岩系为矿区主要赋矿地层,铁矿矿体呈层状、似层状赋存于大盘道组第一岩段,白钨矿矿体呈透镜状和脉状产于铁矿矿体底板围岩中,受片麻状花岗岩与大盘道组大理岩的接触带控制;主要含矿岩石为石榴石矽卡岩和透辉石矽卡岩,钨矿石中主要金属矿物为磁黄铁矿和白钨矿,并含少量磁铁矿、黄铁矿、黄铜矿、闪锌矿、锡石、毒砂和辉钼矿。含钨石英脉中δ^(18)O_水值为3.6‰~7.5‰,δD值为-120.9‰^-66.2‰,表明其成矿流体以岩浆水为主。矽卡岩中与白钨矿共生的金属硫化物δ^(34)S值为16.1‰~18.1‰,^(206)Pb/^(204)Pb值为17.879~18.863,^(207)Pb/^(204)Pb值为15.537~15.603,^(208)Pb/^(204)Pb值为38.202~38.544,表明金属硫化物中的硫和铅主要来源于地层与地壳重熔型岩浆。结合钨矿成矿地质特征,认为羊鼻山铁钨矿床中钨矿的成因类型应属矽卡岩型。

The Yangbishan iron-tungsten deposit is located in Shuangyashan area of Heilongjiang Province,tectonically in the central of Jiamusi massif,the eastern Central Asian Orogenic Belt.The major ore-hosting strata in this area are the metamorphic rock series of Dapandao Formation in Xingdong Group.The layered iron orebodies are mainly hosted in the lowest rock section of Dapandao Formation.The lenticular and vein scheelite orebodies occur in the footwall of iron orebodies,and are controlled by the contact zone between the gneiss granite and the marble of Dapandao Formation.The ore-bearing rocks of tungsten mineralization in the Yangbishan deposit include garnet skarn and diopside skarn.The metallic minerals in the tungsten ore are mainly of scheelite and pyrrhotite,with a small amount of magnetite,pyrite,chalcopyrite,sphalerite,cassiterite,arsenopyrite and molybdenite.The δ18 Oquartz value of scheelite-quartz veins in the Yangbishan deposit is 10.9 ‰-14.8 ‰,the δ18 Owater value is 3.6 ‰-7.5 ‰,and the δD value is -120.9 ‰--66.2 ‰,which show that the ore forming fluid of the scheelite mineralization is dominated by magmatic water.The δ34 S value of metal sulfides in the skarn changes from 16.1 ‰ to 18.1 ‰,206Pb/204Pb value from 17.879 to 18.863,207Pb/204Pb value from 15.537 to 15.603,and 208Pb/204Pb value from 38.202 to 38.544.The data presented in this paper indicate that S and Pb in the metal sulfides mainly came from the ore-hosting strata and re-melted granitic magma.The geological characteristics of the tungsten mineralization in the Yangbishan deposit are similar to those of the skarn-type tungsten deposits.It can be concluded that the scheelite mineralization in the Yangbishan iron-tungsten deposit belongs to skarn-type deposits.