滇西腾冲大硐厂铜-铅-锌矿床的辉钼矿Re-Os同位素定年

Re-Os isotopic dating of molybdenite from Datongchang copper-lead-zinc deposit in Tengchong area, western Yunnan

在环绕印度—亚洲大陆碰撞形成的东构造结波密—腾冲弧形构造带中,发育一组含锡铅_锌_铜多金属矿床,但一直没有准确的成矿年龄数据。文章通过对大硐厂铅_锌矿区红沟岩铜矿体中辉钼矿的Re_Os同位素测试,获得精确的成矿等时线年龄为(118.0±2.4)Ma。区内与成矿关系密切的斑岩成岩年龄在143～112Ma,认为斑岩成岩与成矿同期,同为燕山晚期。

In Bomi-Tengchong arcuate tectonic belt of the eastern tectonic knot formed by Indian-Asian continental collision, lots of stanniferous lead-zinc-copper polymetallic ore deposits are well developed. Their metallogenic ages, however, were not accurately determined. The Re-Os isotopic dating of molybdenite from the Honggouyan copper ore body has yielded the precise ore-forming isochron age of （118.0 ± 2.4） Ma. The porphyries closely related to the ore-forming process in this area have rock-forming ages of 143～112 Ma, suggesting that the petrogenesis and mineralization of the porphyries are of the same epoch, i.e., Early Yanshanian. It is held that, in the melted granite （porphyry） body within the thickened part of the collisional crust, the hydrothermal system rich in ore-forming fluids were superimposed upon the massive sulfide bed and caused its enrichment, thus forming the ore deposit.