摘要
Abstract
The Yanweishan Cu-Ag deposit is a newly discovered medium-small deposit in the Huzhong-Tayuan mineralized belt in the northern Great Xing'an Range.The wall rock aheration is widely distributed in this deposit and alteration minerals mainly include quartz,carbonate,pyrite,illite,kaolinite and sericite.Three ore mineralized stages are recognized:early quartz-pyrite stage (containing little chalcopyrite),main quartz-bornite -chalcopyrite-chalcocite stage and late quartz-carbonate-fluorite stage(containing little galena and sphelarite).The fluid inclusions include abundant fluid-rich two-phase inclusions and few pure-gas one-phase inclusions,without daughter mineral-bearing inclusions.The homogenization temperature of main ore-forming stage ranges from 155℃ to 342℃,concentrating in 160℃ to 230℃.The freezing temperature ranges from-3.3℃ to -0.3℃,displaying the salinity of 0.53％ ～5.41％ NaCleqv.The aqueous components mainly contain K +,Na + and SO42-with a little Ca2 + and Cl-,and a mass of H2O and a little CO2 form the gas of fluid inclusions.The δ18 O and δD of ore-forming fluid vary in-11.8‰ ～-13.72‰ and-105‰ ～-137‰,respectively.Overall,the ore-forming fluid belongs to low temperature and low salinity fluids,which emanated from meteoric water.The characteristics of a fluid,alteration and mineralizing suggest that this deposit is of the high sulfidation epithermal type.Rapid decrease of fluid pressure may be the main mechanism of ore-forming materials precipitation.The Yanweishan deposit may represent a new type of deposits in the Huzhong-Tayuan mineralized belt and subsequent research could help understand the metallogeny and clarifying prospecting direction.关键词
偃尾山铜银矿床/围岩蚀变/流体包裹体/氢氧同位素/浅成低温热液矿床/大兴安岭Key words
Yanweishan Cu-Ag deposit/wallrock alteration/fluid inclusion/hydrogen-oxygen isotope/epithermal deposit/Great Xing'an Range分类
天文与地球科学
