The "trinity" geological model for ore prospecting and prediction of the Dashui gold mine in Maqu County, Gansu Province

Based on the "trinity" prospecting theory proposed by Ye Tianzhu et al., this paper summarizes the metallogenic geological bodies, metallogenic structures, metallogenic structural planes and characteristics of mineralization through the study of geological processes, metallogenic structures, mineralization alterations and various kinds of metallogenic information of the Dashui gold mine.Then the "trinity" metallogenic model was constructed, which provides a geological model for the next prospecting and prediction.The metallogenic geological body of the Dashui gold deposit is Late Triassic Geer inclusive rock mass and derived veins.The metallogenic structure is controlled by NW-trending regional faults, late NE-trending and nearly NS-trending faults.The main metallogenic structural planes are mainly fault structures, contact faces of different lithologies, and paleokarst structure.The characteristics of mineralization are mainly silicification, hematitization, limonitization and calcitization.The metallogenic fluids belonged to the system of H₂O-NaCl-CO₂, and the main components of fluid gas were CO₂ and H₂O.Calcite, limestone carbon and oxygen isotopes and pyrite sulfur isotopes indicate that ore-forming materials were mainly derived from magma.The deposit was formed in the middle-shallow depth, and the gold mineralization occurred in a relatively reduced environment.