延边东部杨金沟金矿床成矿时代与成矿物质来源

杨金沟金矿床位于吉林省珲春市春化镇,大地构造位置上地处兴蒙造山带最东端。为了确定其成矿时代以及成矿物质来源,选取金矿石中与金矿化密切相关的辉钼矿和黄铁矿分别进行Re-Os定年和S同位素测试分析。辉钼矿的Re-Os等时线年龄为(247.6±5.8)Ma,模式年龄的加权平均年龄为(250.6±1.8)Ma,结合已有白云母Ar-Ar测年和含矿岩体锆石U-Pb测年结果,确定杨金沟金矿床的形成时代为晚二叠世末至早三叠世初。金矿石中黄铁矿的δ~(34)S值介于0.59‰~2.70‰,接近陨石硫δ~(34)S值,故硫源主要来自于上地幔;辉钼矿的Re质量分数介于2.87×10~(-4)~5.64×10~(-4),也表明其成矿物质主要来源于地幔。根据成矿地质条件、矿床地质特征、成矿物质来源、成矿构造背景以及同类矿床对比研究,认为杨金沟金矿床是东北地区晚古生代金矿床的典型代表,其成因上属与造山作用有关的中温热液脉型金矿床。

Metallogenic age and ore-forming material source of Yangjin'gou Gold Deposit in eastern Yanbian region

Yangjin'gou Gold Deposit is located in Chunhua Town,Hunchun City,Jilin Province,and tectonically in the easternmost part of Xing'an-Mongolia Orogenic Belt.The Re-Os isotopic dating and S isotopic analysis are conducted on molybdenite and pyrite respectively,which are closely related to gold mineralization in the gold ores,to determine the metallogenic age and ore-forming material source.The Re-Os isotopic dating of the molybdenite shows that the isochron age is (247.6 ± 5.8) Ma and the weighted average age of the model age is (250.6 ± 1.8) Ma,which,combined with the existing results of muscovite Ar-Ar dating and zircon U-Pb dating for ore-bearing rock,can conclude that the Yangjin'gou Gold Deposit formed at the end of Late Permian or the beginning of Early Triassic.The δ34S values in the pyrite range from 0.59 ‰ to 2.70 ‰,close to the meteorite sulfur δ34S value,indicating that the sulfur resource mainly comes from the upper mantle.Besides that,the Re mass fraction of molybdenite ranges from2.87 × 10-4 to 5.64 × 10-4,which suggests that the metallogenic minerals also mainly come from the mantle.Such research data as geological conditions,geological features,tectonic setting and ore-forming material source and the comparison with other similar deposits indicated that the Yangjin'gou Gold Deposit is one representative Neopaleozoic gold deposit in NE China,whose genesis belongs to the mesothermal vein-type gold deposit formed in the orogenic tectonic activities.