Abstract
The Mibei gold deposit,located in the southwestern part of the Xuefengshan uplift zone,the middle section of the Jiangnan orogenic belt in southern China,has estimated gold resources of approximately seven tons.This deposit is primarily a quartz vein-type gold deposit,with ore bodies occurring mainly within Neoproterozoic metasediments.The main metallic minerals in the ore are pyrite,chalcopyrite,and arsenopyrite.In this study,the petrography and microthermometry of ore-forming fluid inclusions,oxygen isotopes of gold-bearing quartz,and sulfur isotopes of gold-bearing sulfides and arsenopyrite were analyzed.Three types of fluid inclusions were identified:type Ⅰa three-phase inclusions comprising vapor and two phases of liquids(VCO2+LCO2+LH2O),type Ⅰb two-phase liquids(LCO2+LH2O),typeⅡ two-phase vapor-rich inclusions(V/V+L＞50％),and type Ⅲ pure liquid inclusions.Type Ⅰ inclusions were heated uniformly to the liquid phase,type Ⅱ inclusions were heated uniformly to the gas phase,and type Ⅲ inclusions were heated without change.In general,the temperature range of homogenization to liquid phase of fluid inclusions in the Mibei gold deposit is 204-227℃.The salinity of the inclusion ranges from 4.6 to 12.2 wt％NaCl equiv.The δ18OSMOW of gold-bearing quartz varies from 16.9‰ to 17.5‰.The δ18OH2O of gold-bearing quartz are varied from 6.5‰ to 7.5‰.The δ34S values of gold-bearing pyrite range from 1.7‰ to 6.8‰.The δ34S values of gold-bearing arsenopyrite range from 5.6‰ to 5.9‰.Theδ34S values of pyrite from wall rocks slate range from 6.4‰ to 11.6‰.This evidence implies that the ore-forming fluids of the Mibei gold deposit originated from magmatic-hydrothermal processes,mixing with minor S from the surrounding metasediments.Combined with the evolution of the Jiangnan orogenic belt,due to the magmatic and tectonic activities of the Xuefengshan uplift during the Caledonian period,the fault seal mechanism controlled the ore-forming process.Overall,the Mibei gold deposit is more akin to a magmatic-hydrothermal gold deposit.
基金项目
National Natural Science Foundation of China(42273063)
Young Elite Scientists Sponsorship(YESS)Program of the China Association for Science and Technology(YESS20220661)
国家科技期刊平台
NSTL
万方数据