Computational simulation of coupled geodynamics for forming the Makeng deposit in Fujian Province, China: Constraints of mechanics, thermotics and hydrology

• Application of computational geoscience method to do the coupled geodynamics simulation.
• Temporal-spatial variation of temperature, fluid flow and strain in model controls ore location.
• Simulation results show modeling to be effective for selecting targets of concealed orebodies.

The Makeng Fe (–Mo) deposit is the largest iron deposit in the Southwestern Fujian metallogenic belt of southeast China. This deposit's genesis has been disputed since the 1950s, with the primary view being that of the skarn type. Detailed geological investigations of the deposit were conducted to elucidate the ore-forming processes at work, as well as its localization. The investigations were based on computational geodynamic models that were, in turn, constructed by simulating the syn-extensional cooling of the ore-related intrusion. We have developed a FISH program to transform the MIDAS/GTS geometric solid model into the FLAC3D geodynamic discrete model. The occurrence of the granite xenoliths in ores and the sharp boundary of the ore body suggest that the ore body was formed at the tensile fracture spaces of the host rocks. The results of the numerical simulation show that most ore bodies are located in the weak zones of the limestone strata with dilation zones that are well-developed. Thus, the fluids from different sources can be easily focused due to the coupled mechano–thermo-hydrological (MTH) processes. The ore forming processes are closely related to the mechanical properties of sedimentary strata, especially regarding its competence and the contact relationship with different rock units. The computational model shows the same depth found through deep geological drilling, which also identified significant ore bodies. The simulation model will facilitate the selection of targets for further exploration of concealed deposits.