吉林省中东部季德屯及石马洞大型钼矿床辉钼矿Re-Os同位素年龄及地质意义

报道了季德屯、石马洞大型钼矿床地质特征,并对季德屯及石马洞钼矿辉钼矿样品分别进行了Re--Os同位素分析。所获季德屯大型钼矿床辉钼矿的模式年龄值为(168.79±0.42~169.91±0.47)Ma,加权平均年龄为169.31 Ma,等时线年龄为(169.1±1.8)Ma(MSWD=7);石马洞大型钼矿床辉钼矿的模式年龄值为(164.85±1.46~166.21±0.90)Ma,加权平均年龄为165.66 Ma,等时线年龄为(169.3±1.9)Ma(MSWD=1.3)。这些年龄说明两个矿床成矿年龄均为中侏罗世,与大黑山等钼矿成矿年龄基本一致。结合区域上已有的研究成果,认为吉林省中东部钼矿成岩成矿作用主要集中在早—中侏罗世。通过区域构造演化和区域钼矿矿床特征及成岩成矿年龄的分析,认为吉林省中东部大规模钼矿的成矿与太平洋板块的俯冲作用的联系更为密切。

Re- - Os isotopic dating of molybdenites from Jidetun and Shimadong large molybdenum deposits in centro- eastern Jilin and its geological significance

The geological characteristics of Jidetun and Shimadong large molybdenum deposits are reported． Re- -Os isotopic dating of molybdenite shows that the Re- -Os model age of Jidetun molybdenum deposit is from (168. 79 ±0. 42) Ma to (169. 91 ±0. 47) Ma，averaging of 169. 31 Ma，with the isochron age of (169. 1 ±1. 8) Ma (MSWD =7); the age of Shimadong molybdenum deposit is from (164. 85 ±1. 46) Ma to (166. 21 ±0. 90) Ma，averaging of 165. 66 Ma，with the isochron age of (169. 3 ±1. 9) Ma ( MSWD =1. 3)． These ages indicate that the molybdenum deposits formed in Middle Jurassic，which consistent with the forming age of Daheishai molyb- denum deposit and its contemporary ones． According to the geochronologic data obtained，it is assumed that the molybdenum mineralization in centro- eastern Jilin largely took place during the Early- Middle Jurassic． Based on the analysis of regional tectonic evolution，deposit characteristics and petrologenesis and metallogenesis ages，it is con- sidered that the large- scale molybdenum mineralization in centro- eastern Jilin was closely related to the intensive subduction of the Pacific Plate to Eurasian Plate．