甲岗雪山W-Mo多金属矿床位于西藏自治区申扎县境内,地处冈底斯北部,成矿时代为中新世。矿床与矿区内的二长花岗岩体时空关系紧密,矿区内的围岩蚀变普遍见云英岩化,并且云英岩化强烈的地方多伴随强烈的钨钼矿化;矿体的类型以云英岩型为主,还有少量石英脉型,矿石又多呈细脉状或浸染状赋存于云英岩或云英岩化二长花岗岩体内部,证实了矿床的成因类型为云英岩型。依据野外见到的矿物共生组合、脉体穿切关系等,可将成矿期划分为硅酸盐-氧化物阶段和硫化物阶段。流体包裹体研究表明,甲岗雪山W-Mo多金属矿床主成矿期的成矿流体为中-高温、中-低盐度的流体,从主成矿期的硅酸盐-氧化物阶段演化到硫化物阶段,成矿流体的温度下降明显,盐度也有所下降。
The Jiagangxueshan W-Mo polymetallic deposit in Xainza County of Tibet is located in northern Gangdise belt, and its metallogenic time is Miocene. The deposit is closely related to the monzogranite located at the center of the deposit temporally and spatially. Greisenzation is the commonest wall rock alteration, and the positions where there exist intense greisenzations usually have relatively good mineralization. The types of orebodies are mainly greisen-type and subordinately quartz vein-type. Moreover, mineralization styles are dominantly veinlet and dissemination forms, and W-Mo ores usually occur in greisen or greisenized monzogranite. In conclusion,the genetic type of Jiagangxueshan W-Mo polymetallic deposit is greisen-type. Based on mineral assemblages and crosscutting relationships, the ore-forming stages may consist of an early silicate-oxide stage, followed by a sulfide stage. The microthermometric study of fluid inclusions shows that the W-Mo mineralization is relevant to ore-forming fluids at moderate to high temperature and low-middle salinity. From the silicate-oxide stage to sulfide stage, the temperature of the ore-forming fluids decreased obviously and the salinity decreased slightly as well.