Age and Source of the Jinjingzui Skarn-Type Gold Deposit in the Southeastern Hubei Province, China

The Jinjingzui gold (Au) deposit is located in the central part of Edong, China. The theoretical gold reserves are large with significant potential for mining and future development. This deposit is the only Au-bearing deposit discovered in the Middle-Lower Yangtze River Valley Metallogenic Belt, which has existing ore bodies that are mainly diorite. Re–Os dating of molybdenite from the Jinjingzui deposit confirm that the deposit formed in the Lower Cretaceous period, with an isochron age of 138.5 ± 2.7 Ma. The geochemical data of the rocks indicate that the diorite contains 54.75% to 56.66% SiO2, 5.68% to 8.94% Fe2O3, 2.05% to 2.19% MgO, and 1.06% to 1.08% TiO2, and with enrichment of large-ion lithophile elements (e.g., Rb and Ba). High-field-strength elements U-Nb–Ti displayed strong negative anomalies. Six pyrites from the Jinjingzui Au deposit δ34SV-PDB(‰) ranged from −2.4% to −8.4%, with an average value of −3.1%, and 206Pb~204Pb, 207Pb~204Pb, 208Pb~204Pb contents ranged from 17.77–18.58, 15.48–15.67 to 37.91–39.05, with average values of 18.14, 15.59 and 38.49, respectively. These values indicate that the metallic components originated from the upper mantle and lower crust. The Re concentrations in the molybdenites are significantly higher than those in other ores within the district (847.91~2018.58 × 10−6), suggesting a significant mantle component was involved in the mineralization process.