湖南渣滓溪锑钨矿床流体包裹体特征及其意义

湘中锑矿带中的渣滓溪锑钨矿床,是我国典型的大型脉状充填型锑矿床,前人对其成矿流体研究较少,该矿的矿石沉淀机制和成矿过程,目前尚不清楚。本次采用红外显微测温和传统显微测温相结合的方法,对渣滓溪矿区的白钨矿、辉锑矿及与其共生的石英中的流体包裹体,进行了系统的岩相学和显微测温研究。研究表明,该区矿物中发育的流体包裹体有四种类型,纯液相包裹体、富液相的气液包裹体、富气相的气液包裹体和纯气相包裹体。该区白钨矿中流体包裹体的均一温度为147～285℃,盐度为2.4%～6.0%NaCleqv,与其共生的石英中流体包裹体的均一温度为147～314℃,盐度为3.1%～6.2%NaCleqv;辉锑矿中流体包裹体的均一温度为124～269℃,盐度为0.4%～4.5%NaCleqv,与其共生的石英中流体包裹体的均一温度为114～298℃,盐度为0.2%～5.9%NaCleqv,成矿流体为一种中温、低盐度,以H2O为主的热水溶液。该区钨矿石中的白钨矿和石英、锑矿石中的辉锑矿和石英分别具有相似的均一温度和盐度。钨矿石和锑矿石具有不同的沉淀机制,前者是由于流体混合作用导致的,而后者则是由于流体沸腾引起的。湘西浅变质...

Characteristics and Significance of the Fluid Inclusions from the Zhazixi Sb-W Deposit,Hunan Province

The Zhazixi W-Sb deposit,located in the Xiangzhong antimony ore belt,is one of typical vein-filled hydrothermal deposits in China.The ore-forming fluid of this Sb-W deposit is poorly constrained,and its ore precipitation mechanism and mineralization process remain unclear.In order to ascertain the signature of the ore-forming fluids responsible for different ores,we conducted infrared microthermometric and conventional microthermometric measurements on the fluid inclusions in scheelite and co-genetic quartz,stibnite and intergrown quartz collected from the Zhazixi Sb-W deposit.Four types of fluid inclusions were identified based on petrography,including pure liquid inclusions,liquid-rich two-phase aqueous inclusions,vapor-rich two-phase aqueous inclusions and pure vapor inclusions.The aqueous fluid inclusions in scheelite have homogenization temperatures of 147 to 285℃,and salinities in range of 2.4%to 6.0%NaCleqv,and the homogenization temperatures and the salinities for those in quartz associated with scheelite vary in ranges of 147–314℃,3.1%–6.2%NaCleqv,respectively.The homogenization temperatures and salinities for aqueous fluids in stibnite vary in ranges of 124 to 269℃and 0.4%–4.5%NaCleqv,respectively,and those for aqueous fluids in co-genetic quartz vary in rangs of 114–298℃and 0.2%–5.9%NaCleqv,respectively.The ore-forming fluid belongs to a kind of the mesothermal,low-salinity,H2O-predominant hydrothermal solution.The fluid inclusions in ore minerals(scheelite and stibnite)and their coexisting quartz share similar homogenization temperatures and salinities.There are two different mechanisms for different ores in the Zhazixi Sb-W deposit,the formation of W ores probably resulted from fluid mixing;however,boiling was responsible for the precipitation of Sb ores.Those antimony deposits hosted in metamorphic rocks in the Xuefeng Range(Western Hunan)and carbonate rocks in Xiangzhong Basin(Central Hunan)exhibit different mineralization process and ore precipitation mechanism.In the Xuefeng Range,ore minerals and gangue minerals in antimony ores have similar homogenization temperatures and salinities,they are likely deposited simultaneously from the same hydrothermal solution triggered by fluid boiling.In contrast,for those antimony deposits hosted in the carbonates in the Xiangzhong Basin,ore minerals and gangue minerals display distinct homogenization temperatures and salinities,they are possibly deposited from two different kinds of hydrothermal solution due to fluid mixing.