Zircon U-Pb Geochronology and Uranium-Production Capacity of the Taoshan Complex in Southern Jiangxi

The Taoshan granite complex located at the North-East part of the Nanling region, hosts the largest granite-related uranuim ore field in China. Baohuashan granite and Huangpi granite are two major components of the Taoshan granite complex. The formation age of Baohuashan granite was in the Indosinian period, which is more closely associated with uranuium ore, however, only individual uranium ore has been found in Baohuashan granite. Huangpi and Daguzhai granites have the same age of (154±2) Ma, but this is in conflict with the field geological phenomena, i.e. Huangpi granite was intruded by Daguzhai granite. High precision techniques of Laser Ablation-Multicollector Inductively Coupled Plasma-Mass Spectrometry (LA-MC-ICPMS) have been used to re-determine the emplacement age of these two plutons and the method is reported in this paper. The results indicate that Baohuashan granite was formed in the Indosinian era (229.98±0.98) Ma, and the Huangpi granite was formed in the early Yanshanian era (160.9±2.4) Ma. The emplacement age of Huangpi granite is a little earlier than Daguzhai granite, which is more aligned with the geological facts. Combining with previous studies, the magma evolutionary sequence, tectonic environment and uranium-production capacity of Taoshan complex are discussed. The magma evolutionary sequence of Taoshan complex was classified into five main stages, which is composed of Baohuashan granite in Indonisian, Huangpi and Daguzhai granites in early Yanshanian, Luobuli and Caishan granite in late Yanshanian. Granite formed at deferent stage belongs to deferent genesis type. The formation of Indonian and Yanshanian granite in Taoshan complex was speculated to related extension tectonic environment caused by subduction of pacific plate. We pointed out that the genesis type of granite is a primary controlling factor for uranium-production capacity of granites. The Daguzhai granit, which is an S-type granite, has the greatest uranium-production capacity. There is a need for further study to determine the underlying reasons for the genesis type controlling uranium-production capacity of granite.