Objective The East Kunlun Orogenic Belt (EKOB) is one of China's most significant metal ore-forming regions, housing a multitude of metal deposits, including Fe, Au, Cu, Ni, and Mo. Recent uranium exploration results have also demonstrated that the EKOB may be a crucial area for hydrothermal uranium deposits. Further research and analysis are required to comprehensively understand the geological conditions and characteristics of U mineralization in this area. To determine the hydrothermal uranium mineralization events in the EKOB and explore the regional uranium mineralization potential,

Methods U-Mo mineralization at Nakexiuma in the EOKB was selected. Basing on the summarizing the geological features, the ore-forming epoch was explored.

Results U mineralization at Nakexiuma primarily occurs within the fractures of quartz schists within the Tanjianshan Formation. Primary uranium minerals identified are uraninite and brannerite, indicating a high-temperature hydrothermal U mineralization. Elemental analysis shows that most uraninite analyses from the Nakexiuma area exhibit low concentrations of Ca, Si, and Fe, moderate to low contents of Th, and moderate to high U/Th ratios. The chemical ages (U−Th−Pb) of these analyses range from 229 Ma to 280 Ma, with the smallest U−Th−Pb age likely representing the age of U mineralization at Nakexiuma.

Conclusions This age aligns with the youngest granitic magmatic age at Nakexiuma, suggesting that hydrothermal fluids may have originated from the Triassic granitic magmatism. Building upon previous research, this study proposes the possibility of an Early Mesozoic hydrothermal U mineralization event in the northwest China. The areas that develop Paleozoic to Mesozoic igneous rocks in the NW China should be a focal point for future uranium exploration.