广东高州石龙金矿床成矿流体地球化学研究

Study on ore-forming fluid geochemistry of Shilong gold deposit in Gaozhou, Guangdong

广东石龙金矿床是与燕山期中酸性-次火山岩有关的金矿床,矿化类型有角砾岩型、黄铁矿-多金属硫化物细脉充填型及破碎蚀变岩型。金多金属矿脉均赋存于NE向的韧-脆性剪切变形变质带内。通过对矿石中的石英、重晶石和闪锌矿中流体包裹体测定,其均一温度(Th)在115°-305°C之间,盐度(S)在2.07-11.7%NaCleqv之间。拉曼分析结果表明:流体主要成分是H2_O,另有少量CO_2、H2_S和CH_4等。应用同步辐射X射线荧光微探针无损分析技术,对石英流体包裹体中的微量元素进行了测定,一般含金矿石品位高的样品,其流体包裹体中的Au含量亦高;相应铁含量也高,但包裹体中Pb、Zn的含量则不一定都高。结合成分分析和前人研究结果,认为成矿流体主要来自大气降水,矿床属于中低温浅成热液金矿床。

The Shilong gold deposit in Guangdong are related to the acid volcanic rocks in Yanshanian, and the mineralization types are breccia type, pyrite-polymetallie sulphide filling type and crushing alteration rock type. The polymetallie veins are all in the north-eastern ductile-brittle shear deformation metamorphic zone. The homogeneous temperature（Th） is between 115-305 ℃ and the salinity （S） is between 2.07-11.7 % NaCleqv as measured by fluid inclusions in quartz, barite and sphalerite in ores. Laser Raman Spectroscopy analysis showed that there are mainly H2O, and a small amount of CO2, HaS and CH4 in the fluid inclusions. The trace elements in fluid inclusions of quartz were measured by synchrotron X-ray fluorescence microprobe nondestructive analysis technique. When the gold ore has a high grade, the content of Au in the fluid inclu- sions was also high, but the Pb, Zn content in inclusions is not necessarily high. Combined with the composi- tion analysis and previous research results, it is believed that the ore-forming fluid is mainly from atmospheric precipitation, and the deposit is a medium-low-short hydrothermal gold deposit.