Affiliation:
1. School of Civil and Resource Engineering University of Science and Technology Beijing Beijing 100083 China
2. Geophysical and Geochemical Survey Institute of Hunan Changsha 410116 China
3. New Geological Energy Exploration and Development Engineering Technology Research Center of Hunan Changsha 410116 China
4. State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences (Beijing) Beijing 100083 China
5. Comprehensive Survey Command Center for Natural Resources China Geological Survey Beijing 100055 China
Abstract
AbstractThe 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), type II 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°C. 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‰. The δ34S 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.
Reference107 articles.
1. Gold mineralization events of the Jiangnan Orogen in Hunan and their tectonic settings;Bai D.Y.;Acta Petrologica et Mineralogica,2021
2. Summary of main mineralization events in Hunan Province;Bai D.Y.;Geology in China,2022
3. Study on the deformation in the southern Xuefeng orogenic belt;Bai D.Y.;Geotectonica et Metallogenia,2014
4. UNCLOAKING INVISIBLE GOLD: USE OF NANOSIMS TO EVALUATE GOLD, TRACE ELEMENTS, AND SULFUR ISOTOPES IN PYRITE FROM CARLIN-TYPE GOLD DEPOSITS
5. A method of calculating fluid inclusion volumes based on vapor bubble diameters and P-V-T-X properties of inclusion fluids