内蒙古林西萤石矿床石英ESR年龄及其地质意义

内蒙古林西地区萤石矿床主要赋存于晚古生代-中生代火山-沉积地层和酸性侵入岩体中，矿体主要受南北向和北北东向断裂破碎带控制。萤石矿床中共生有大量同期形成的石英（脉），运用石英热活化电子自旋共振（ESR）测年法，对萤石矿床中8件与萤石共生的石英进行年代学研究，来探讨林西萤石矿床的形成时代。结果表明，林西萤石矿床中的石英ESR年龄范围为126.6～157.3 Ma，平均年龄为137 Ma，表明研究区萤石矿床成矿时代主要为侏罗纪晚期-白垩纪早期。与全球其他地区萤石矿床成矿时代对比，并结合本区萤石矿床地质特征，认为林西萤石矿为中-低温热液裂隙充填型萤石矿床，形成于燕山中期板内构造体制转换时期。

ESR Dating of Quartz from Linxi Fluorite Deposits,Inner Mongolia and Its Geological Implications

The Linxi fluorite deposits, Inner Mongolia, are mainly hosted in the vocanic-sedimentary stratum and acidic intrusions in the Late Paleozoic-Mesozoic, controlled by the NS and the NNE trending fault zone. Quartzs (quartz vein) are massively formed within the same period in the deposit. The ESR dating was used to study the fluorite-forming time by measuring the 8 pieces of paragenetic quartz samples in the deposits. The results show that the ESR dating of quartzs from Linxi fluorite deposits ranges from 126.6 to 157.3 Ma, with an average of 137 Ma, indicating that the metallogenic hydrothermal fluid mainly formed in the Late Jurassic-Early Cretaceous. Combined with geological characteristics of deposits and the global fluorite deposits, Linxi fluorite deposits are of hydrothermal origin, and of fracture-filled metasomatic type, which are formed in the conversion period of the middle Yanshanian stage intraplate tectonic regime.