Tectono-magmatic activization and fractal dynamics of hydrothermal uranium ore formation in South China

South China includes two typical Cathysian Diwa regions (i.e., Southeast Diwa and Kiangnan Diwa regions). The complicated multi-stage tectono-magmatic evolution resulted in the widespread granites, and Mesozoic-Cenozoic rifted basins, as well as NE-NNE and NW trending deep faults, and led to the formation of numerous hydrothermal uranium ore deposits. Fractal analyses and numerical simulation of the spatial distribution of faults, granite bodies and uranium ore deposits with fractal distribution were used to discuss the tectono-magmatic activization and fractal dynamics of hydrothermal uranium mineralization in South China, based on the theories of polygenetic compound and tectonic unit metallogeny. The calculated box counting dimensions of faults from Southeast Diwa and Kiangnan Diwa regions were 1.6800 and 1.5939, respectively, indicating that the faults in the former region are favorable for uranium mineralization. The calculated box counting dimension (D) and perimeter-area fractal dimension (DPA) of the granite bodies emplaced during Precambrian to late Yanshanian periods indicated that the D values increase with the granite outcrop area while DPA values increase with the granite shape complexity, demonstrating the strengthening complexity of tectono-magmatic activization. In addition, the D and DPA values of the granite bodies during the periods of Late Yanshanian, Early Yanshanian and Indosinian were relatively high, demonstrating that they also facilitated uranium mineralization. On the other hand, the calculated values (i.e., 1.0254) of box counting dimension of hydrothermal uranium ore deposits in South China are significantly lower than that of faults, consisting with the low distribution density and enrichment of uranium ore deposits. Our simulated results of Cellular Automata Model show that the fractal dimension values of faults and mineralization increase with time, and the large-scale mineralization occurs when these values reach the critical condition of fractal penetration during the mid-late stage simulation. Overall, the fractal evolution of complicated multi-stage tectono-magmatic activization in the two typical Cathysian Diwa regions produced the fractal distribution characteristics of polygenetic compound hydrothermal uranium deposits in South China. ©, 2015, Science Press. All right reserved.