THE RELATIONSHIP BETWEEN STRUCTURE AND METALLOGENESIS IN THE LAILISHAN TIN DEPOSIT IN YUNNAN PROVINCE

The Lailishan tin ore field in Yunnan Province is located in the western margin of the south section of Sanjiang tectonic zone, where fault structures are especially developed. With analysis on the characteristics of ore-controlling structure in the ore field, the relationship between structure and metallogenesis are discussed. It is believed that fault structures play an important role in the process of mineralization. The faults in the ore field are characterized by multistaged movement, with compresso-shear in the early and tenso-shear in the late. The post-magmatic ore-bearing hydrothermal fluid migrates along the contact fracture zone or external fracture zone and forms the ore by filling and replacing. Therefore, the fault structures are the necessary conditions for mineralization. The mineralization is closely dependent on the structure.