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为确定小西南岔铜金矿床的成矿时代,对北山矿段新发现的含辉钼矿石英脉进行了系统研究和同位素测年.空间上,含辉钼矿石英脉与相邻铜金矿体平行,它们受相同的构造体系控制;钼矿石中金属矿物以辉钼矿为主,并明显被黄铜矿和黄铁矿沿裂隙、晶隙充填交代,根据不同矿物间的交生关系,结合前人研究资料认为,该辉钼矿石英脉是该区大规模铜金矿化的早期阶段产物.在此基础上,对6件辉钼矿样品进行了Re-Os同位素分析,获得的模式年龄为109.2±3.4 Ma~110.8±4.0 Ma,平均年龄为109.9±3.9 Ma,等时线年龄为111.1±3.1 Ma,与该区燕山晚期花岗岩类最新测年结果具明显的耦合关系,为小西南岔矿床提供了一个准确的形成时限.综合辉钼矿中低的Re含量、成矿岩体岩石学、地球化学特征以及精细的同位素年代学研究认为,该区大规模铜金矿化主要发生于燕山晚期,成矿构造环境为伊泽奈崎板块向古亚洲大陆边缘俯冲造成的岩石圈伸展背景下的活动陆缘环境,成岩成矿物质具深源特征,主要来自上地幔.
In order to confirm the metallogenic epoch of XiaoxiNancha copper-gold deposit, systematic study and isotopic dating of newly discovered molybdenite-bearing quartz veins were conducted in the Beishan ore deposit.In space, They are dominated by the same tectonic system. The molybdenum ore is dominated by molybdenite and is obviously replaced by chalcopyrite and pyrite along fractures and interspaces. Depending on the relationship between the different minerals, According to the previous research data, the vein of molybdenite is the early stage product of large-scale copper-gold mineralization in this area.On this basis, six molybdenite samples were analyzed by Re-Os isotope analysis, and the obtained model The age ranged from 109.2 ± 3.4 Ma to 110.8 ± 4.0 Ma with an average age of 109.9 ± 3.9 Ma and an isochron age of 111.1 ± 3.1 Ma, which was obviously coupled with the latest dating results of late Yanshan granitoids, Bifurcated ore deposit provides an accurate time limit for formation.Recently, the low Re content of molybdenite, the petrology, geochemical characteristics and fine isotopic chronology of the metallogenic rocks suggest that the large-scale copper-gold mineralization mainly occurs in Yanshan late, the metallogenic tectonic environment for Iraq Active continental margin environment of lithospheric extension background Chennai Kawasaki plate to ancient Asian continental margin subduction caused by diagenetic minerals into a deep source or characteristics, mainly from the upper mantle.