Abstract
The Jiaodong Peninsula, located along the western margin of the Paleo-Pacific Plate, hosts one of the world's largest gold provinces with over 5,500 tonnes of proven gold resources. Despite its economic significance, the mechanisms of mineralization and the nature of ore-controlling structures remain debated. This study is primarily based on structural analysis, field observations, core drilling, and Electron Backscatter Diffraction (EBSD), supplemented by regional geochronological data, to investigate the tectonic evolution of ore-controlling structures during the Yanshan orogenic event. Numerous thrust and strike-slip faults have been identified, all overprinted by later detachment faults. A tectonic transition from NW–SE compression to NW–SE extension is identified at ∼135 Ma. The main gold mineralization event occurred at ∼120 Ma, postdating this transition. Two contemporaneous end-member types of mineralization are recognized: disseminated-type deposits in low-angle detachment faults (∼two-thirds of resources) and quartz vein-type mineralization in steeply dipping fractures (∼one-third), formed in structural sites with distinct geometric characteristics. We integrate the fault-valve and the more recently developed mode-switching models to explain the spatial zonation between the two mineralization styles, attributing their formation to periodic changes in ore-forming fluid behavior controlled by fluctuations in effective stress, fluid pressure, and permeability. Our findings highlight the critical role of tectonic transition and structural evolution in controlling the large-scale enrichment of gold deposits in the Jiaodong region and, through the first application of the mode-switching model to this area, provide a novel unified genetic framework for these giant ore deposits.