西藏申扎县甲岗雪山钨、钼、铋多金属矿床稳定同位素地球化学特征及矿床成因探讨

冈底斯成矿带是西藏重要的多金属成矿区之一,在该成矿带北部申扎县首次发现的甲岗雪山钨、钼、铋多金属矿床是不同于其南部斑岩型铜多金属矿床的成矿新类型,该矿床的发现是藏北地区内生金属矿找矿的重要突破.文章对该矿床矿石稳定同位素地球化学特征进行研究表明:成矿流体主要来源于岩浆岩,围岩(地层)可能只提供了少量成矿物质;该矿床硫的来源单一,属于岩浆硫范畴,矿石与围岩中的硫具有相同的来源;铅的来源以地壳铅为主,并混有少量地幔铅.根据上述研究,结合矿床地质特征及同国内外同类型矿床的对比,认为甲岗雪山多金属矿床是在大陆碰撞后陆内伸展构造背景下,形成于喜马拉雅中期中酸性岩浆活动阶段,矿质主要源自岩浆的石英大脉型钨、钼、铋多金属矿床.

STABLE ISOTOPE AND ORE GENESIS OF JIAGANGXUESHAN W-Mo-Bi POLYMETALLIC DEPOSIT , SHENZHA COUNTY,TIBET

Gangdisi belt is one of important polymetallic ore belts in Tibet. First found Jiagangxueshan W - Mo - Bi polymetallic deposit in the north Gangdisi belt is a new mineralizing type and different from porphyry Cu - dominant polymetallic deposits in the south belt. It is a breakthrough for ore - finding in the northern Tibet. Stable isotope analysis results of the deposit show that ore - forming fluids came from manna, and wallrocks might provide less metallogenic materials. Sulfur of both ores and wallrocks derived from magma. Lead was mainly from the Crust, and mixed with little mantle lead. Based on above results, geological characters and comparison with the same deposits abroad, it is concluded that the deposit was formed in the middle Himalaya medium- acid magmatic period, and on the background of intercontinental extensional structural regime after continental collision. It is a large quartz vein type W - Mo - Bi polymetallic deposit.