辽东地区王家崴子金矿古元古代金预富集矿化事件

The Wangjiawaizi gold deposit is a middle tonnage and quartz-vein type deposit in the Maoling gold district of Liaodong Peninsula, China. The orebody is hosted in the Gaixian Formation of Paleoproterozoic Liaohe Group, and is mainly controlled by a series of nearly parallel NW ductile shear zones in the mine area. In this study, we studied pyrite that is genetically closely related to gold mineralization, as well as sphalerite and galena for S-Pb isotopes and trace elements characteristics by using in-situ microanalytic techniques. LA-MC-ICP-MS in-situ S isotope analyses show that sulfides from the Wangjiawaizi gold deposit yielded 8 S values of 8. 2%c ~ 11. 5%c, which is significantly higher than that of magmatic sulfur, but overlaps with the range of 8 S value of the Gaixian Formation, thus inferring that the sulfur in the ore-forming fluids is derived from the Gaixian Formation. The in-situ Pb isotope analyses by LA-MC-ICP-MS show that sulfides yielded ²⁰⁸Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb, and ²⁰⁶Pb/²⁰⁴Pb ratios of 39. 000 - 39. 084, 15.691 -15.707, and 18. 623 - 18. 664, respectively. They cluster near the upper crust evolution line and plot in the field of the Gaixian Formation, indicating that the Pb was primarily derived from the upper erustal rock of the Gaixian Formation. LA-ICP-MS trace element analyses show that pyrite yielded low Co/Ni and Te/Au ratios, and is obviously enriched in Au, As, Ag, Cu, Pb and Zn, indicating a metamorphie-hydrothermal origin. In combination with previous research, we propose that there is an early stage of Paleoproterozoic gold pre-enrichment in this Maoling gold district, and that the subsequent Early Jurassic magmatie-hydrothermal activity extracted the pre-enriched ore-forming materials from the Gaixian Formation to account for most of the gold mineralization in the Wangjiawaizi deposit. The Gaixian Formation is a significant source bed lor gold mineralization in the Liaodong Peninsula, which should be given full attention in future mineral exploration work.