Ore-forming simulation of the Axi low-sulfidation epithermal gold deposit, Western China: Genetic implications on mineralization pattern

Abstract

Improving the understanding of fluid migration and mineralization localization within epithermal gold systems is of utmost significance for mineral exploration. In this study, a series of numerical simulation experiments were carried out at the Axi low-sulfidation epithermal gold deposit in western China under variable stress conditions by employing the FLAC^3D software. The objective was to explore the fluid migration process during the ore-forming period. The results demonstrate that the extensional deformation and fluid migration patterns of simple compressive or tensional model cannot yield the known mineralization distribution, while the corrected 30° tension model leads to sinistral strike-slip, resulting in the current gold mineralization pattern. The NE-trending fault extension zone associated with the deformation setting is inferred as the migration pathway of the deep-seated ore-forming fluids. Several deep fluid migration pathways beneath the known mineralization are determined. Numerical simulation of the metallogenic process reveals that the fault structure controls the scale and extent of fluid migration. The gold distribution in the Axi deposit can be ascribed to shear strain localization, the development of dilation, and the focusing of fluids into the dilatant fault. By means of thermo-fluid-mechanical coupling, the models have generated several potential gold mineralization targets in the southern and northern segments. This case study emphasizes that the mineralization of the Axi gold deposit is predominantly controlled by fault geometry associated with specific stress directions and demonstrates that numerical modeling is a robust tool for identifying potential mineralization.