Abstract:

 Exploration over the past two decades indicates that the PaleoAsian orogenic belts across north China and MesozoicCenozoic continental basins around their both sides are the most important metallogenic tectonic domain for the formation of the depositiontype uranium deposits in China. The Paleo-Asian orogenic belts are essential uraniumrich geological bodies. The uranium delivery system depends on the transportation of the surface drainage restricted by basinmountain coupling mechanics. Mudstonetype uranium deposits were fed by the single uranium source, whereas sandstonetype uranium deposits were fed by the double uranium source, and the regenerated uranium source originated from uranium reservoirs is quite important. Slack and sustained geotectonic background during the dormant period of the trustorogeny process and the postfault thermal subsidence is a period favorable to the formation of depositionalmetallogenic environment. Mudstonetype uranium deposits need synsedimentary sustained tectonic setting.Sandstonetype uranium deposits were formed under not only the synsedimentary sustained tectonic setting, but also the tiptilting tectonic setting during the mineralization period. Some sandstonetype uranium deposits were obviously affected by the tectonic setting after mineralization. Survey indicates that the efficiency of interlayer oxidation is the highest, and the transported flux of uranium is the largest, and the large even super large uranium deposits tend to be formed when the mineralcharged flow field during the mineralization period was consistent to the synsedimentary palaeocurrent. Synsedimentary palaeoclimate is a significant geologic factor affecting the development of uranium reservoirs and interlayer oxidation zone, which constrained not only the architecture and size of uranium reservoirs, but also the types of reductive media inside and outside uranium reservoirs and their spatial distribution. The morphology and architecture of uranium reservoirs restricted the direction and track of interlayer oxidation zone, whereas the reductive media inside and outside uranium reservoirs controlled the advancing mileage and location of frontal line of the interlayer oxidation zone. Uranium mineralization is related to the redox geochemical barrier. This study shows that the MesozoicCenozoic basins around the PaleoAsian orogenic belts are primary prospective area for depositiontype uranium deposits. Based on the indepth analysis of the regional tectonic framework and rechargerunoffdischarge system of the mineralcharged flow field, the prospecting target can be delineated and evaluated according to the synsedimentary palaeoclimate, types of reductive media and their spatial distribution of uraniumbearing series in the target basin.

Key words: sandstonetype (mudstonetype) uranium deposits, tectonic domain of uranium mineralization, PaleoAsian orogenic belts, MesozoicCenozoic sedimentary basins