西藏列廷冈铁多金属矿床辉钼矿Re-Os定年及其地质意义

列廷冈铁多金属矿床不仅是西藏林周盆地已发现的众多铁多金属矿床中工业价值、找矿远景最好的矿床之一,而且是冈底斯成矿带Fe、Cu、Mo、Pb、Zn等多矿化元素组合的典型代表。本次研究利用辉钼矿Re-Os同位素年代学测试方法,对列廷冈矿床8件辉钼矿进行了精确定年,首次明确了矿床成矿时代。测试结果表明,辉钼矿模式年龄为(60.97±0.92)Ma~(63.19±0.93)Ma,等时线年龄为(62.28±0.66)Ma(MSWD=0.74),矿床形成于古新世,与印度—亚洲大陆主碰撞阶段在冈底斯成矿作用有关。矿床辉钼矿Re含量变化于0.54×10-6~84.72×10-6,指示矿床成矿物质来源主要为壳幔混源。列廷冈矿床成矿时代和成矿物质来源的厘定,对于区域上开展古新世铁多金属矿床的找矿预测具有十分重要的意义。

Re-Os dating of molybdenite from the Lietinggang iron polymetallic deposit of Tibet and its geological significance

Abstract: Among lots of polymetallic deposits, the Lietinggang deposit in the Lhunzhub Basin of Tibet is one of the deposits with best industrial?value and exploration prospect. It is a?typical deposit where Fe, Cu, Mo, Pb and Zn have been found. High precision Re-Os dating was conducted for 10 molybdenite samples for determining the mineralization age of the Lietingang deposit. It is for the first time that the high precision mineralization age of the deposit has been obtained. The test result indicates that the Re-Os model ages vary in the range of (60.97+0.92) Ma-(63.19+0.93) Ma, and the isochron age is (62.28+0.66) Ma, with MSWD being 0.74. During the main Indosinian collision period in the Gangdise belt, the deposit was formed in the Paleocene. The Re values of 8 pieces of molybdenite are mainly concentrated in the range of 0.54×10-6-84.72×10-6. The sources of the ore-forming materials were mainly from the Earth''s mantle and crust. The determination of the ore-forming epoch and metallogenic material of the Lietinggang deposit is of great significance for the regional ore-prospecting prognosis of early Paleocene iron-polymetallic deposits.