Numerical Modeling Of Structure Stress Field In The Beiya Gold Ore Deposit, Yunnan, China

Liberation, migration and concentration of the ore fluids are related with the structure stress field. Tectonic process is not only to provide the channels and space for the fluid movement but more important to provide the impetus and some energy for them. The tectonic stress field in the mineralization period is important to understand the formation mechanical of the ore-control structural, ore-fluild migration model and gold mineralizational enrichment regularity. Based on field observations, laboratory testings and analysis, elastic-plastic model of Beiya gold deposit is established to inversion the spatial-temporal structure of the ore-control tectonic stress field and to study its tectonic-fluid-metallogenic dynamics characteristics using the structure-fluid-metallogenic system theory. The following conclusions are reached: (1)The tectonic differential stress is 180MPa in the early mineralization when the ductile deformation is dominant and the maximum compressional stress axis is EW direction. The tectonic differential stress is 80MPa in the Main mineralization when the brittle deformation is dominant, and the maximum compressional stress axis is SN direction; (2)The nearly SN trending faults are the rock control and mineral control structures. The maximum principal stress, minimum principal stress,average principal stress of these faults and the the area around these faults are anomalous.The location of trend and strike change of the fracture is favorable for mineralization; (3) Thermal stress field results show that the stress of the area near the main fault is smaller than the fault, which indicate the area is more favorable for the fluid to converge; (4)Tectonic metallogenic dynamic model of this gold deposit is established by the above understandings.