西藏驱龙—甲玛—邦铺铜矿集区铅同位素地球化学示踪研究  

Lead Isotope Geochemistry in the Qulong—Jiama—Bangpu Ore Concentrated Area of Tibet

作　　者：应立娟[1] 王阔[2] 王开建[2] 

机构地区：[1]国土资源部成矿作用与资源评价重点实验室中国地质科学院矿产资源研究所,北京100037 [2]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《岩矿测试》2016年第3期320-328,共9页Rock and Mineral Analysis

基　　金：中国科技部重大仪器专项(2011YQ050069);国家自然科学青年基金资助项目(41302058);中国地质大调查项目(12120114019401)

摘　　要：驱龙—甲玛—邦铺铜多金属矿集区是西藏冈底斯成矿带上的重要矿集区,铜资源量超过1500万吨。前人研究认为三个矿床成矿物质来源于岩浆,但未讨论不同时代、不同矿化的岩浆岩铅同位素与矿石铅同位素组成的关系,并缺乏从矿集区尺度来分析。本文通过分析已发表的矿石、岩浆岩和地层铅同位素数据,认为驱龙、甲玛、邦铺矿床矿石铅与中新世含矿斑岩铅同位素特征基本一致,区别于与成矿无关的岩浆岩铅同位素组成。空间上,从南西的驱龙,至甲玛,至北东的邦铺,成矿年龄从老到新,铅同位素演化规律明显,放射成因铅递增(矿石206Pb/204Pb平均值18.521→18.644→18.684)。这种铅同位素地球化学特征不仅指示了成矿物质来自岩浆,并可区分与成矿有关和无关的岩浆岩,同时指示了成矿期岩浆岩与成矿关系的密切程度。The Qulong-Jiama-Bangpu copper polymetallic ore concentration area is one of the most important areas in the Gangdese metallogenic belt of Tibet with more than 15 million tons of copper resources. Ore-forming materials for three deposits were considered to be derived from magma.However,the relationship between magma with different degrees of mineralization and times and copper mineralization are unknown,especially on a regional scale.By collecting the published lead isotope data of ores,intrusions and strata from these three deposits,the lead isotopic composition of ores from Qulong,Jiama and Bangpu are were found to be similar to those of Miocene orebearing porphyries but different from those of intrusions unrelated to mineralization. Spatially,from Qulong in the southwest,to Jiama,and to Bangpu in the northeast,the mineralization ages range from old to young,and lead isotopes evolve obviously with radiogenic lead increments( average206 Pb /204 Pb values of ores 18. 521 →18. 644 →18. 684). Lead isotope geochemistry not only indicates the magma source,but also can differentiate between orerelated intrusions from ore-barren intrusions and suggest the relationship between intrusion and mineralization.

关 键 词：铅同位素 成矿物质来源 驱龙-甲玛-邦铺 铜矿集区 

分 类 号：O614.433[理学—无机化学]