Numerical modeling of structural reactivation and its controls on the formation of the Douzhashan granite-type uranium deposits, South China

Abstract

Granite-type uranium deposits are spatially associated with granitic rocks but structurally controlled and hydrothermal in nature. The Miaoershan-Yuechengling region is regarded as one of the most significant granite-type uranium resource areas in South China. Specifically, the Douzhashan uranium orefield, located in the middle of the Miaoershan pluton, is primarily controlled by secondary fault zones trending NE and NNE. Previous studies indicate that the fault zones have undergone multiple periods of structural reactivation. Nevertheless, the effects of structural reactivation on the spatial distribution of uranium deposits remain unclear. In this study, two-dimensional numerical simulations were conducted on the Douzhashan uranium orefield to investigate the effects of stress field direction and depth on the dilational zones generated by fault activation and to examine the relationship between strain distribution and uranium deposits. The simulation results indicate that the pre-existing NE- and NNE-trending faults provided favorable mineralization space through developing dilational zones during extensional tectonic deformation. Furthermore, the distribution characteristics of the dilational zones under the conditions of depths of 3–4 km were found to be relatively more consistent with the known distribution of uranium deposits, suggesting that the uranium mineralization may occur at depths of 3–4 km. These findings provide valuable insights into the controlling factors for the spatial distribution of uranium deposits in the Douzhashan uranium orefield as well as future exploration in this area.