Study On Deformation Characteristics Of Yangshan Gold Belt, Gansu Province

Yangshan gold deposit in southern Gansu Province is one of China’s large gold deposits, it is located in a complex convergence zone of several plates. Tectonic deformations in this zone are complex and intense. Therefore, we conducted research on structure staging and structural deformation analysis relying on "the Yangshan gold deposit belt tectonics ore control regularity research" project.In this paper, we learn from previous studies and also use the theory of structural analysis and the methods of structure comparison, through field observations to summarize both surface and underground, macro- and micro-structural deformation characteristics. And finally complete the study of deformation characteristics of Yangshan Gold deposit. The understandings we got are as follows:Yangshan gold deposit has developed a large number of penetrative foliations, lineations and a variety of styles of fold structures. The preferred trend of lineations is 108o; The preferred trend of Fold hinges is 110o;The preferred dip of foliations is NNE, average attitude is 45o∠50o. These conclusions show that the main regional tectonic stress direction is NNE-SSW. Yangshan gold deposit has developed a large number of microstructures that showing ductile-brittle deformation characteristics. The main regional tectonic stress direction shown is 18-330° which matches the result of previous attitude measurements. Based on the observational study of the thrust nappe, both north and south borders, in Yangshan gold belt we determined that the Yangshan gold belt has the deformation characteristics of ductile passage flow. According to the observational studies of surface and underground structures we have divided four recognizable tectonic stages. And based on the observed characteristics of the different vein stages, combined with the stress characteristics of each tectonic stage, we have summarized the mechanism of the coupling between deformation stages and vein stages.