塔里木板块东北部坡十侵入体铂族元素地球化学特征及成矿作用

Geochemical Characteristics of the Platinum Group Elements from the Poshi Intrusion,Northeastern Tarim Block and Its Mineralization

坡十侵入体位于塔里木板块东北部坡北岩体内,是该岩体第三阶段岩浆活动形成的十几个小侵入体中的一个。现有钻探资料显示其主要岩石类型有:纯橄岩、二辉橄榄岩、斜长二辉橄榄岩、橄榄二辉岩、正堆晶辉长岩。其中,含矿岩石主要为二辉橄榄岩。矿石构造以星散浸染状-稀疏浸染状为主,局部具稠密浸染状构造。铂族元素(PGE)地球化学特征表明,原生岩浆为高镁玄武质岩浆,演化过程中深部发生了约0.012%硫化物熔离,使得侵入体现有岩石和矿石的PGE含量总体偏低。综合坡十侵入体的岩体特征、矿体在侵入体中赋存的部位、矿石类型和矿石结构/构造分析,现阶段评价的矿(化)体主要为含有少量硫化物的上悬矿体,侵入体深部找矿潜力较大。

The Poshi intrusion is located within the Pobei rock body northeast of the Tarim block. It is one of the small intrusions formed during the third magmatie stage of the Pobei rock body. The drilling data show that the main rock types are dunite, lherzolite, pl-lherzolite, olivine websterite and gabbro. The sulfide occurred in the lherzolite. Disseminated sulfide is dominant in the Poshi ore body. Geochemical characteristics of the platinum group elements indicate that the primary magma is high-MgO basaltic lnaglna, and the Poshi parental magma may have experienced about 0. 012% sulfide remov- al, resulting in the low content of the PGE. The characteristics of the intrusion, types, textures and structures of ores suggest a great potential of ore- search in the deep Poshi intrusion.