ORE FLUID GEOCHEMISTRY OF THE JINLONGSHAN CARLIN-TYPE GOLD ORE BELT IN SHAANXI PROVINCE, CHINA  

作　　者：张静 陈衍景 张复新 李超 

机构地区：[1]STATE KEY LABORATORY OF GEOLOGICAL PROCESSES AND MINERAL RESOURCES, CHINA UNIVERSITY OF GEOSCIENCES, BEIJING 100083, CHINA,LABORATORY OF CRUST AND OROGEN EVOLUTION, PEKING UNIVERSITY, BEIJING 100871, CHINA [2]LABORATORY OF CRUST AND OROGEN EVOLUTION, PEKING UNIVERSITY, BEIJING 100871, CHINA, INSTITUTE OF GEOCHEMISTRY, CHINESE ACADEMY OF SCIENCES, GUIYANG 550002, CHINA [3]DEPARTMENT OF GEOLOGY, NORTHWEST UNIVERSITY, XI'AN 710069, CHINA [4]LABORATORY OF CRUST AND OROGEN EVOLUTION, PEKING UNIVERSITY, BEIJING 100871, CHINA

出　　处：《Chinese Journal Of Geochemistry》2006年第1期23-32,共10页中国地球化学学报

基　　金：GRANTEDBYTHENATIONALNATURALSCIENCEFOUNDATIONOFCHINA(PROJECTSNOS.49672119,49972035,40352003,AND40425006)ANDTHEHUNDREDYOUNGSCIENTISTSPROGRAMOFCHINESEACADEMYOFSCIENCES.

摘　　要：The Jinlongshan gold ore belt in southern Shaanxi Province contains a number of Carlin-type gold deposits in the Qinling collisional orogenic belt. Their fluid inclusions are of the Na-Cl- type. From the main metallogenic stage to later stages, the total quantity of anions and cations, temperature and deoxidation parameter (R) for fluid inclusions all gradually decreased, suggesting the gradual intensification of fluid oxidation, the reduction of metallogenic depth and the input of meteoric water and organic components. The deposits were formed during crustal uplifting and hence had similar tectonic settings to orogenic gold deposits. The CO-2 contents and CO-2/H-2O values of the ore fluid increased from early to late stages, and the wall-rock alteration is represented by decarbonation, which is inconsistent with the characteristics of orogenic gold deposits. It is also discovered that Na, K, SO{2-}-4, Cl- and the total amounts of anions and cations in the inclusions in quartz are higher than those in the coexisting calcite. The H, O and C isotope ratios indicate that the ore fluid was sourced from meteoric water and metamorphic devolatilisation of the sedimentary rocks that host the ores. The high background {δ{}{18}O} and {δ{}{13}C} values of wall rocks resulted in high {δ{}{18}O} and {δ{}{13}C} values of ore fluid and also high {δ{}{18}O} and {δ{}{13}C} values of hydrothermal minerals such as quartz and carbonate. The carbon in ore fluid stemmed largely from the hosting strata. The {δ{}{18}O} and {δ{}{13}C} values of Fe-calcite and the δD values of fluid inclusions are lower than those of calcite and quartz. In terms of the theory of coordination chemistry, all these differences can be ascribed to water-rock interaction in the same fluid system, instead, to the multi-source of ore fluid.The Jinlongshan gold ore belt in southern Shaanxi Province contains a number of Carlin-type gold deposits in the Qinling collisional orogenic belt. Their fluid inclusions are of the Na^＋ - Cl^- type. From the main metallogenic stage to later stages, the total quantity of anions and cations, temperature and deoxidation parameter （R） for fluid inclusions all gradually decreased, suggesting the gradual intensification of fluid oxidation, the reduction of metallogenic depth and the input of meteoric water and organic components. The deposits were formed during crustal uplifting and hence had similar tectonic settings to orogenic gold deposits. The CO2 contents and CO2/H2O values of the ore fluid increased from early to late stages, and the wall-rock alteration is represented by decarbonation, which is inconsistent with the characteristics of orogenic gold deposits. It is also discovered that Na^＋, K^＋ , SO^2-4, Cl^- and the total amounts of anions and cations in the inclusions in quartz are higher than those in the coexisting calcite. The H2 O and C isotope ratios indicate that the ore fluid was sourced from meteoric water and metamorphic devolatilisation of the sedimentary rocks that host the ores. The high background δ^18O and 8 δ^13C values of wall rocks resulted in high δ^18O and δ^13C values of ore fluid and also high δ^18O and δ^13C values of hydrothermal minerals such as quartz and carbonate. The carbon in ore fluid stemmed largely from the hosting strata. The δ^18O and δ^13C values of Fe-calcite and the 8D values of fluid inclusions are lower than those of calcite and quartz. In terms of the theory of coordination chemistry, all these differences can be ascribed to water-rock interaction in the same fluid system, instead, to the multisource of ore fluid.

关 键 词：矿带 金 流动性 同位素 

分 类 号：P59[天文地球—地球化学]