New sight for gold forming system in Wulong deposit: Indicated by the distal Pb-Znmineralization in hydrothermal breccia

Wulong deposit is a typical quartz vein-type gold deposit formed in the Early Cretaceous in Liaodong Peninsula. We reported characteristics of a newly found Pb-Zn mineralization spot in hydrothermal breccia and it's closely associated with a diorite dike in the distal area of Wulong gold deposit, and it may be helpful for further understanding the ore-forming system in the area. The breccia was probably formed in a process of hydrothermal explosive fracturing. Galena and sphalerite occurred in the quartz cement or quartz veins. Miarolitic cavities, comb quartz layers, mineralization and alteration can be found in the diorite below or by the breccia, which can indicate the Pb-Zn mineralization are genetically associated with the diorite. The delta O-18(H2O) and delta DV-SMOW values of quartz from the cement and veins are -2.7 parts per thousand similar to 0.1 parts per thousand. and -71.5 parts per thousand similar to -85.9 parts per thousand, which support a mixture of magmatic and meteoric fluids, the same as the late hydrothermal stage fluids in Wulong gold deposit. Moreover, U-Pb dating of the zircons from the diorite yield Pb-206/ U-238 mean age of 120.9 +/- 1.3Ma, which was nearly coeval with Wulong deposit. The diorite shows closely spatial, temporal, and geochemical relationships with Wulong ore-forming system, and it can be taken as a "bridge" to connect magmatism and mineralization. The diorite belongs to the high-K calc-alkaline series, with enrichment in light rare earth elements and large-ion lithophile elements, and depletion in high-field-strength elements. The (Sr-87/Sr-86) epsilon(Nd), (t), and epsilon(Hf) (t) values of measured samples from the diorite are 0.711 similar to 0.712, -8.2 similar to -9.0 and -21.2 similar to -22.8, respectively. It can be inferred that the diorite is mainly originated from enriched lithospheric mantle which are enriched in compatible elements and provided materials for the Au mineralization. The quartz-vein type gold lode in Wulong and the distal Pb-Zn mineralization area belong to an ore-forming system related to intrusion, and it can be predicted that sheeted ore-hosting veins and disseminated mineralization lie in the contact zone of deep-seated dioritic stocks or pluton.