Uranium Source of the Miao'ershan Uranium Orefield,Northern Guangxi:Constraints from Detrital Zircons in the Faulted Red Basin
The source of granite-related hydrothermal uranium deposits is still controversial,and red basins around the uranium deposits are believed to be the source of ore-forming materials.The Miao'ershan is a typical granite-related uranium orefield in South China,however,the relationship between the red basin and the uranium deposit remains unclear.To determine the formation age and material source of classic rocks in the red basin and discuss the source of the uranium deposit,the petrography,detrital zircon U-Pb dating,and trace element characteristics of the clastic rocks from the red basin in the Miao'ershan area were analyzed.The CL images and rare earth element characteristics indicated that the zircon grains are magmatic origin.LA-ICP-MS U-Pb dating of the detrital zircons yielded an age range of 416-2485 Ma,with the main peaks of 721-839 Ma and 416-436 Ma,which are consistent with the timing of the Jinningian Period and Caledonian tectonic-magmatic events in the Miao'ershan uranium ore field.EPMA element maps of the altered zircon grain from the clastic rock samples indicated that the zircon grains show strong fluid metasomatism,and the obvious activation and migration of uranium recorded the alteration and mineral dissolution-precipitation processes.Considering of the chronological data of granites in the surrounding areas,we suggest that the detrital zircons of 721-839 Ma mainly derived from the Neoproterozoic Jingningian Period granites in the Miao'ershan area and the Neoproterozoic granites in the Chengbu area of Hunan province.The zircons of 416-436 Ma mainly originated from the Yuechengling-Miao'ershan Galedonian granite batholith.Based on the previous data,it is believed that part of the uranium in the Miao'ershan uranium ore-field originated from the clastic rocks in the Xinzi faulted red basin.The CO2-rich mantle derived fluids rose along the deep faults,and mixed with the circulating groundwater to form hydrothermal fluids,which interacted with U-rich granites and clastic rocks,released the uranium in the rocks,and formed uranium-rich ore-forming fluids.
Xinzi faulted red basinMiao'ershan uranium fielddetrital zirconchronologyrare earth elementsuranium source
万方数据
维普
