陕西金龙山卡林型金矿带成矿流体地球化学研究  

Geochemical Study of Ore Fluid in Jinlongshan Carlin-type Gold Ore Belt in Southwestern Shaanxi Province

作　　者：张静[1] 陈衍景[1] 张复新[2] 李超[1] 

机构地区：[1]北京大学地球与空间科学学院 [2]西北大学地质学系,陕西西安710069

出　　处：《矿床地质》2002年第3期283-291,共9页Mineral Deposits

基　　金：国家攀登课题(95_预 3 9_0 4);南京大学内生矿床国家重点实验室;自然科学基金项目(编号:49672 119和 49972 0 3 5);教育部跨世纪人才基金项目资助

摘　　要：陕西金龙山金矿的流体包裹体研究表明,成矿流体属于Na+ _Cl-型;从成矿早期到晚期,流体的氧化性逐渐增强,成矿深度逐渐变浅,大气降水混入增多,有机组分增多。石英包裹体的Na+ 、K+ 、SO2 -4、Cl-以及阴、阳离子总量都高于同期共生的方解石,而Mg2 + 和F-则相反;含铁方解石的δ13 C、δ18O和包裹体δD均低于方解石和石英。用配位化学理论将这些差异解释为同一流体系统水岩作用的结果。氢、氧、碳同位素指示了流体主要来自建造水和大气降水;The Jinlongshan gold ore belt in Shaanxi Province is a Carlin_type gold deposit in a typical collisional orogenic zone. Its fluid inclusions are of the Na +_Cl - type. From main metallogenic stage to late stage, the total quantity of anions and cations, temperature, and deoxidation parameter R of fluid inclusions all gradually decreased, which suggests the gradual intensification of fluid oxidation, the reduction of metallogenic depth, and the increase of meteoric water and organic components. The deposits were formed during the uplifting of the crust in the orogenic belt and hence had the similar tectonic setting with orogenic gold deposits. The CO 2 and CO 2/H 2O values of the ore fluid increase from early to late, and the wall_rock alteration is represented by decarbonation, which is quite inconsistent with the rule of ore fluid evolvement and water_rock interaction of orogenic gold deposits in greenstone belt and volcanic rock body. The analyses of H, O, C isotopes indicate that the water in ore fluid is interlayer water and meteoric water stored in wall rock formation. The high δ 18 O and δ 13 C background values in the wall rock resulted in the relatively high δ 18 O and δ 13 C values of ore fluid and also the rather high δ 18 O and δ 13 C values of the quartz and carbonate minerals in this deposit. The carbon in ore fluid mainly came from the surrounding strata. It is also discovered that Na +, K +, SO 2- 4, Cl - and total quantity of anions and cations in the inclusions in quartz are all higher than their values in the coexisting calcite; nevertheless, things are just the opposite for Mg 2+ and F -. The δ 18 O and δ 13 C values of Fe_calcite and δD of inclusions are lower than these values in calcite and quartz. With ligand chemistry theory, all these differences can be explained as the result of water_rock reaction in the same fluid system instead of as the multisource nature of the fluid (e.g. binary mixture).

关 键 词：陕西 地球化学 成矿流体 卡林型金矿带 氧同位素 包裹体 氢同位素 碳同位素 

分 类 号：P618.51[天文地球—矿床学] P597[天文地球—地质学]