湘南州门司脉石英矿床地质特征及成因浅析

Discussion on Geological Characteristics and Genesis of the Zhoumensi Vein Quartz Deposit in Southern Hunan Province

湘南州门司脉石英矿床位于南岭纬向构造带中段北缘,湘东南加里东褶皱隆起带中南部。矿区有一个脉石英矿体,沿断层呈厚层状产于上寒武统小紫荆组地层中,走向控制长度达1.3km,平均厚度达19m,顶底板为浅变质长石石英砂岩。矿石石英含量96.27%~99.00%,含少量铁钛质及粘土矿物,有害组分Cr_(2)O_(3)、TiO_(2)含量较低,可作为平板玻璃用优质硅质原料。根据地质特征、岩矿分析及包裹体测温结果,研究认为形成脉石英矿的富硅热液可能来自深部岩浆分异;断裂是导矿容矿构造,当富硅热液温度降至152~263℃时,二氧化硅开始沉淀并充填于断层裂隙中;断裂的继承性活动可能是形成两期石英的原因;矿床成因类型为中低温热液型脉石英矿床。

The Zhoumensi vein quartz deposit in the southeastern Hunan province is located at conjugation of the north margin of the middle section of the Nanling zonal structural belt and the south-central part of the Caledonian fold uplift bel.There is only one vein quartz ore body in the deposit,which is thick bedded along the fault and occurs in the Xiaozijing formation of the upper Cambrian strata,a controlled length along the strike of 1.3km,and an average thickness of 19m,the top and bottom floor of the ore body are metamorphic feldspar quartz sandstone.The quartz content of the ore is 96.27%~99.00%,a small amount of iron,titanium and clay minerals,and low content of harmful components with Cr_(2)O_(3) and TiO_(2),which can be used as high-quality siliceous raw materials for plate glass.According to the result of geological characteristics,sample analysis and fluid inclusion temperature measurement,study considers the silicon-rich hydrothermal fluid forming vein quartz deposit may come from deep magmatic differentiation,the fault is the metallotectonics structure,when the temperature of silicon-rich hydrothermal fluid drops to 152~263℃,silica begins to precipitate and fill in fissures of the fault,the inheritance of fault may be the reason for the formation of two stages of quartz in this deposit,the genetic type of vein quartz deposit belongs to the middle and low temperature hydrothermal vein quartz deposit.