Geochronology and Genesis of the Shuigou Gold Deposit, Qixia-Penglai-Fushan Metallogenic Area, Jiaodong Peninsula, Eastern China: Constraints from SHRIMP U-Pb, 40Ar/39Ar Age, and He-Ar Isotopes

The Jiaodong Peninsula is renowned for its significant gold reserves, which exceed 4500 tons. In this study, we conducted zircon SHRIMP U-Pb dating, 40Ar/39Ar geochronology, electron probe microanalysis (EPMA) analysis, and He-Ar isotope analysis on samples from the Shuigou gold deposit located in the Qixia-Penglai-Fushan metallogenic area of central Jiaodong. This quartz vein-type gold deposit is characterized by three mineralization stages: (I) the quartz-pyrite stage, (II) the quartz-polymetallic sulfide stage, and (III) the calcite stage. In stages I and II, gold primarily exists as native gold or electrum. Preliminary analysis suggests that the deposit contains rare critical metals, including bismuth (Bi), tellurium (Te), and antimony (Sb). The Sb is found as pyrargyrite in stage III, while the other critical elements occur as isomorphisms or nanoparticles within host minerals such as pyrite, native gold, and electrum. Geochronology data indicate that the pre-mineralization Guojialing monzogranite formed around 126 ± 1.6 Ma, the syn-mineralization muscovite formed at approximately 125 Ma, and the post-mineralization diorite porphyrite formed at 120.4 ± 1.8 Ma. The 3He/4He ratios of fluid inclusions in the main-stage pyrite range from 0.26 to 1.26 Ra, and the 40Ar/36Ar ratios vary from 383 to 426.6. These findings suggest that the Shuigou gold deposit formed during the destruction of the North China Craton (NCC), similar to other super-large gold deposits in the Jiaodong Mesozoic gold metallogenic province. Gold mineralization has been influenced by mantle, crustal, and meteoric fluids.