Mechanism and Tectonic Background of Exhumation History of Volcanic‐Type Uranium Deposits in the Hongshanzi Area of the Great Xing'an Range, Inner Mongolia: Constraints From Apatite Fission Track

ABSTRACT

The Guyuan–Hongshanzi uranium metallogenic belt (GHUMB) in North China, particularly the Hongshanzi area within the southern Great Xing'an Range (GXR), hosts uranium mineralization significantly impacted by post‐mineralization uplift and exhumation. Field investigations, drill core analysis, electron probe microanalysis (EPMA) and apatite fission track (AFT) dating reveal that uranium orebodies occur within basement uplift zones hosted by the Upper Jurassic Manketou'ebo and Xinmin formations, Lower Permian Dashizhai Formation and Hercynian granodiorite. These orebodies are predominantly shallow and are structurally controlled, associated with hydrothermal alteration including carbonatization, silicification, hematitization, chloritization, fluoritization and sulfidization. Critically, deep‐seated potash feldspathization and albitization features are now exposed at shallow depths or the surface. AFT analysis and thermal history modelling indicate rapid cooling during 70–50 Ma, signifying rapid uplift through the partial annealing zone to near‐surface levels. This evidence, combined with the surface exposure of deep alteration, demonstrates that primary uranium mineralization initially formed at depths of ∼2–4 km during the Cretaceous. Subsequent rapid uplift triggered intense erosion, preserving some orebodies shallowly while eroding others and transporting uranium into adjacent basins, potentially contributing to secondary sandstone‐type mineralization.