Spatio-temporal fluid evolution of gold deposit in the Jiaodong Peninsula, China: A case study of the giant Xiling deposit

Abstract

The Xiling gold deposit (>592 t @ 4.02 g/t) in the eastern Zhaoyuan-Laizhou gold belt of the Jiaodong Peninsula, is currently the largest gold deposit and deepest gold mine in China. This study presents microthermometric fluid inclusions data on quartz gangue, as well as trace element and S isotope data on pyrite from different mineralization stages and depths in the Xiling gold deposit to provide new insights into the spatio-temporal evolution of the ore-forming fluid that led to a giant Early Cretaceous gold deposit in the Jiaodong Peninsula. The δ³⁴S values of pyrite range from 7.5 to 15.2 ‰, but vary temporally and spatially, reflecting a changes in physicochemical conditions as the ore-forming fluid migrated to different crustal levels over time, also suggesting Precambrian basement as the principal sulfur source. Trace element analyses of pyrite revealed that ore-forming metals were scavenged from the wall rock and then incorporated into the pyrite. Fluid inclusions data reveal that the ore-forming H₂O-CO₂-NaCl ± CH₄ fluid had a medium to high temperature (283–401 °C), medium-low salinity (1.91–8.00 wt% NaCl equivalent), analogous to most gold deposits in the Jiaodong Peninsula. Intensive interaction between the ore-forming fluid and wall rock changed the physicochemical conditions of fluid, leading to gold precipitation. The study supports the notion of the ore fluid of Jiaodong-type gold deposit having originated from a metasomatized lithospheric mantle.