胶东半岛大磨曲家金矿床成矿流体物理化学条件演化  

Physical-Chemical Conditional Evolution of Ore-forming Fluid in the Damoqujia Gold Deposit in Jiaodong Peninsula

作　　者：郭春影[1,2] 高帮飞[1,2] 张静[1,2] 王庆飞[1,2] 龚庆杰[1,2] 于海军[1,2] 

机构地区：[1]中国地质大学地质过程与矿产资源国家重点实验室,北京100083 [2]中国地质大学岩石圈构造、深部过程及探测技术教育部重点实验室,北京100083

出　　处：《现代地质》2008年第5期743-750,共8页Geoscience

基　　金：国家自然科学基金项目(40572063,40672064);国家“973”项目(2006CB403506);教育部创新团队、“111”计划项目(B07011);教育部“跨世纪人才培养计划”项目;中国地质大学地质过程与矿产资源国家重点实验室开放基金项目(GPMR0732)

摘　　要：胶东大磨曲家金矿床流体包裹体包括水溶液包裹体、富CO2包裹体和高盐卤水包裹体3种类型，前两者发育较多，高盐卤水包裹体发育极少。流体包裹体显微测温及盐度、密度、压力估算显示，水溶液包裹体均一温度为98～376℃，据冰点温度估算，盐度为0．53％～8．28％，水溶液包裹体均一压力低于50×10^5Pa；富CO2包裹体完全均一温度为255～348℃，盐度为2．42％-11．43％，均一压力为1000×10^5～2500×10^5Pa；富CO2包裹体中CO2均一温度为23．0～32．4℃，指示该类包裹体可能含有数量不等的CH4或H2S。静水压力体制下，根据纯CO2包裹体均一压力估算成矿深度约为1km。在270℃左右，均一压力从富CO2包裹体到水溶液包裹体急剧降低，指示成矿流体在270℃左右可能发生过一次减压沸腾过程，成矿流体盐度和密度在270℃左右也有显著的变化。因此，沸腾作用及其引起的成矿流体物理化学条件的急剧变化可能是导致大磨曲家金矿床成矿物质沉淀的重要机制。In the Damoqujia gold deposit, fluid inclusions can be divided into three types, namely aqueous inclusion, CO2-rich inclusion and brine inclusion. The former two types dominate, while the last one is rare. For aqueous inclusions, the homogenization temperatures vary from 98 ℃ to 376 ℃ with salinities varying from 0.53% to 8.28 % and the homogenization pressures are below 50 × 10^5 Pa. For CO2-rich inclusions, the whole homogenization temperatures range from 255 ℃ to 348 ℃ with salinities varying from 2.42% to 11.43% and homogenization pressures are from 1,000 × 10^5 Pa to 2,500 × 10^5 Pa; the CO2 homogenization temperatures vary from 23.0 ℃ to 32.4 ℃ which indicates the existence of CH4 or H2S. The ore-forming depth was estimated at about 1 km, based on homogenization temperatures of pure CO2 inclusions assuming hydrostatic pressure. At about 270 ℃, the homogenization pressures decrease rapidly, indicating that the fluid system experienced a decompression boiling process near 270 ℃ ; at the same time, the salinity and density of ore fluid varied remarkably. Therefore, it is proposed that decompression boiling and related ore fluid dramatic change in physical and chemical properties are responsible for gold deposition in Damoqujia.

关 键 词：金矿床 大磨曲家 流体包裹体 减压沸腾 物理化学条件演化 

分 类 号：P618.1[天文地球—矿床学]