Structural Features of Faults in the Baiyangping-Yanzidong Area of the Lanping-Simao Basin and their Relationship to Mineralization

This paper analyzes the relationship between fault structures and the mineralization in the Baiyangping-Yanzidong area of the Lanping-Simao basin, and establishes a metallogenic model according to the petrology, structure and ore body characteristics in combination with measured sections. It suggests that the Sishiliqing and Huachang Mountain faults have experienced several episodes of activities. When the Triassic rift formed, faults were accompanied with sedimentary processes under an extensional condition as evidenced by normal faults. In the Jurassic and Cretaceous, they became reverse faults due to compressive stress in E-W direction. During the Cenozoic, E-W ramp nappe structures were formed by the continuing E-W directed compression. In the late Triassic, the ore fluids moved along the faults and migrated upward into both sides of the sub-basin to form the first time of exhalative mineralization in the sediment phase. In the Oligocene, the second time of hot brine mineralization started in the form of filling metasomatic reform when the ore-forming fluids migrated into sub-tensile and shear fracture zones of the basin.