延边天宝山多金属矿田辉钼矿Re-Os同位素 年龄及其地质意义

延边天宝山为一大型中高温热液多金属(铅,锌,铜,钼等)矿田,是由新兴铅锌、立山铅锌铜和东风铅锌铜钼3个矿床所组成.文章在矿田地质特征研究的基础上,进行了辉钼矿Re-Os同位素体系定年研究,得到结果w(Re)为0.353～9.306 μg/g,模式年龄为174.7～200.3 Ma,加权平均值年龄为(194.6±3.9) Ma,等时线年龄为(196.6±2.5) Ma(MSWD=0.94,n=9),表明天宝山多金属矿田为早侏罗世岩浆作用及相关流体活动的产物,形成于华北板块和西伯利亚板块碰撞拼合后伸展环境,初步认为成矿物质来源主要为壳源.结合区域上已有的高精度年代学数据,将吉林省中东部山区钼成矿作用划分为2期:早侏罗世(196.6～186Ma)和中侏罗世(176.9～166.9Ma),且以中侏罗世钼矿化最为发育.

Re-Os dating of molybdenite from Tianbaoshan polymetallic orefield in Yanbian and its geological significance

The Tianbaoshan orefield, a large hydrothermal polymetallic (lead, zinc, copper, molybdenum) orefield in Yanbian, is composed of Xinxing lead-zinc deposit, Lishan lead-zinc-copper deposit and Dongfeng lead-zinc-copper-molybdenum deposit. On the basis of geological features, the authors carried out Re-Os dating, and the results show that the Re content of the molybdenite varies from 0.353×10^-6 to 9.306×10^-6, the model ages range from 174.7 to 200.3 Ma with the weighted mean age being (194.6±3.9) Ma and the isochron age bring (196.6± 2.5) Ma(MSWD=0.94, n=9). These data indicate that molybdenum mineralization took place in early Jurassic, and the geodynamic setting was closely related to the extension from the continental collision between the North China Plate and the Siberia Plate. The ore-forming materials might have been derived mainly from the crust. Combined with the high precision chronologic data of regional intrusions,the authors have arrived at the conclusion that Mo mineralization of the middle and east part of Jilin Province can be divided into 2 epochs: Early Jurassic(196.6~186 Ma)and Middle Jurassic(176.9~166.9 Ma), with the Middle Jurassic epoch having stronger mineralization.