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广西大厂矿田产有世界级的超大型锡多金属矿床。亢马锡多金属矿床位于大厂矿田的东成矿带内,矿体主要呈脉状产出于泥盆系黑色页岩中。本文在扫描电镜-X射线激发荧光(SEM-CL)图像分析的基础上,重点对亢马矿床主成矿期锡石-硫化物和碳酸盐-硫盐阶段流体包裹体岩相学、显微测温学及其气相成分的激光Raman光谱进行了系统研究。结果表明,主成矿期锡石-硫化物阶段石英中主要发育富含CO_2气相包裹体和含子晶流体包裹体组合,其均一温度和盐度分别为304～392℃、3%～8%和314～420℃、36%～48%。成矿晚期碳酸盐-硫盐阶段方解石中则仅发育气-液两相盐水流体包裹体,具有较低的均一温度(108～197℃)和盐度(6%～12%)。主成矿期锡石-硫化物阶段富含CO_2气相与含子晶流体包裹体共存、具相近的均一温度以及不同的盐度,推测锡石-硫化物阶段成矿流体经历了流体不混溶(沸腾)过程,流体相分离导致Sn等成矿元素以氯络合物形式进入高盐度的卤水相,其氧化-还原过程可能是导致锡石和硫化物沉淀富集最重要的成矿机制,而成矿晚期碳酸盐阶段的流体可能主要来源于富含CO_2气相流体的冷凝过程。
Guangxi Dachang ore field produces world-class super-large tin polymetallic deposits. The Kangma tin polymetallic deposit is located in the East metallogenic belt of the Dachang orefield. The ore body is mainly vein-shaped in the Devonian black shale. Based on the SEM-CL image analysis, this paper focuses on the petrography of fluid inclusions in the cassiterite-sulphide and carbonate-sulphite phases of the main metallogenic stage of the Kangma deposit, Micro-temperature measurement and gas-phase laser Raman spectroscopy were systematically studied. The results show that the main stage of cassiterite-sulphide quartz in the main metallogenic stage is mainly composed of CO 2 gas inclusions and sub-inclusion fluid inclusions, and their homogenization temperatures and salinities are respectively 304-392 ℃ and 3% -8% And 314 ~ 420 ℃, 36% ~ 48%. Only the gas-liquid two phase brine fluid inclusions are developed in the late stage of carbonate-sulfur calcite, with lower homogenization temperature (108-1970C) and salinity (6-12%). During the main mineralization, the cassiterite-sulphide-rich phase enriched in CO 2 gas coexists with sub-inclusion fluid inclusions with similar homogenization temperatures and different salinities. It is presumed that the cassiterite-sulphide stage ore-forming fluids have undergone fluid immiscibility (Boiling), the phase separation of fluid leads to the formation of high-salinity brine by Sn and other mineral elements. The oxidation-reduction process may be the most important metallogenic mechanism leading to the precipitation and accumulation of cassiterite and sulfide. The late stage of metallogenic carbonate fluid may be mainly derived from the condensation of gas-phase CO2-rich fluid.