南秦岭西峡县尹家沟石墨矿床地质特征及成因分析

Geological characteristics and genetic analysis of the Yinjiagou graphite deposit in Xixia County,south Qinling orogen

西峡尹家沟石墨矿床位于南秦岭淅川—商南石墨成矿带的东部,是新发现的具有大型规模的晶质石墨矿床。矿体赋存于古元古界陡岭群大沟岩组中深变质岩系中,矿体呈层状、似层状产出,主要含矿岩石为白云母石墨片岩,少量的石墨斜长片麻岩。主量元素整体表现为高Si、高Al、低碱、低烧失量的特点,通过地球化学图解认为原岩为含碳质杂砂岩和长石砂岩,石墨矿变质岩系的沉积环境可能为大陆岛弧沉积。综合分析认为,碳质来源为有机碳,尹家沟石墨矿床成因类型属沉积变质型矿床,石墨矿床具有后期叠加热接触变质进而富集的特征。该研究可为淅川—商南石墨矿带石墨找矿和研究提供支撑。

The Yinjiagou graphite deposit in Xixia is located in the east of Xichuan-Shangnan graphite metallogenic belt in the south Qinling orogen,which is a newly discovered large-scale crystalline graphite deposit.The ore body occurs in the middle-deep metamorphic rock of the Dagou formation of Paleoproterozoic Douling group.The ore body occurs as layers and stratoid,and the main ore bearing rocks are muscovite graphite schist and some graphite plagioclase gneiss.The major elements are characterized by high Si,high Al,low alkali and LOI.According to geochemical diagrams,the original rocks are carbonaceous greywacks and arkose,the sedimentary environment of graphite metamorphic rock may be formed in continental island arc deposition.Comprehensive analysis shows that the carbon source is organic carbon,the genetic type of Yinjiagou graphite deposit belongs to sedimentary metamorphic deposit.The graphite deposit has the characteristics of superimposed heating contact metamorphism and enrichment in the later stage.It provides support for graphite prospecting and research in Xichuan-Shangnan graphite ore belt.