Uranium Sources and Depositional Environments in Southeastern Mongolia: Case Studies from the Han Bogd Granite Massif, Ail Bayan Coal Deposit, Suujin Tal Structural System, Zuunbayan Depression, and Naarst Structural Complex

Uranium exploration in southeastern Mongolia remains constrained by fragmented Soviet-era datasets and limited modern synthesis. This study addresses the problem of integrating historical geological records with contemporary exploration methods to evaluate uranium mineralization potential. A comprehensive GIS-based database was compiled from Soviet reports legally acquired from the Mineral Resources Authority of Mongolia and expanded with geological, geophysical, and drilling data collected between 2006 and 2011. Methodological advances included remote sensing detection of anomalous radioactivity in arid environments, stratigraphic modeling, and hydrogeochemical surveys. The dataset encompasses more than 1100 radioactive anomalies and approximately 300 mineralized zones, with emphasis on the Han Bogd granite massif, Ail Bayan coal deposit, Suujin Tal structural system, Zuunbayan depression, and Naarst structural complex. Results indicate that most anomalous zones are sub-economic, commonly associated with organic-rich facies such as coal seams, while the continuity of mineralized bodies remains uncertain. Nevertheless, the dual consideration of granitic source terrains and coal-bearing sedimentary traps provides new insights into uranium mobility and deposition. The significance of this work lies in its systematic integration of historical and modern data, offering a refined geological framework and highlighting key areas for future investigation, thereby contributing to ongoing discussions on sedimentary uranium resources in Mongolia. Results indicate that most anomalous zones are sub-economic, commonly associated with organic-rich facies such as coal seams, while the continuity of mineralized bodies remains uncertain. Importantly, the study highlights granitic intrusions and volcanic complexes as the primary uranium sources, with coal-bearing and sedimentary basins acting as secondary depositional environments. The dual consideration of source terrains and depositional traps provides new insights into uranium mobility and deposition.