Uranium-bearing and barren granites from the Taoshan Complex, Jiangxi Province, South China: Geochemical and petrogenetic discrimination and exploration significance

The Taoshan uranium ore district is one of the most important granite-hosted uranium producers in South China. The Taoshan granitic complex can be petrographically classified into several units of Caijiang, Huangpi, Daguzhai, and Luobuli, but the uranium deposits only occur within the Daguzhai granite unit. LA-ICP-MS zircon U–Pb dating indicates that both the Daguzhai granite and the Huangpi granite were emplaced at 154 ± 2 Ma. U contents (average 19.5 ppm) of the Daguzhai granite are higher than those of the Huangpi granite (average 7.3 ppm). The Daguzhai granite is composed of medium-grained two-mica granite, and the Huangpi granite is composed of medium- to coarse-grained biotite granite. These two granites show obvious differences in major element, trace element and isotopic geochemical characteristics. Compared to the Huangpi granite, the Daguzhai granite has higher A/CNK ratios, higher P2O5 contents and lower CaO contents, and is more enriched in Rb, Ba, U, and more depleted in Sr, Eu and Ti. The εNd(t) values of the Daguzhai granite vary from − 12.2 to − 11.0 with two-stage model ages of 1.84 to 1.93 Ga. The εNd(t) values of the Huangpi granite are slightly higher (− 9.7 to − 8.6) and the Nd model ages are younger (1.64 to 1.73 Ga). Comparative studies imply that the Daguzhai granite belongs to typical S-type and might be derived from the partial melting of parametamorphic rocks from metamorphic basement of the Zhoutan Group. In contrast, the Huangpi granite belongs to fractioned I-type, which might be derived from the partial melting of a mixture of ortho- and para-metamorphic rocks of the Zhoutan Group. These different magma sources might explain the different U contents of the two granites. In general, the source factor is an important controlling factor for the genesis of U-bearing granites in South China. U-bearing granites in South China show some common mineralogical and geochemical characteristics, which can be used to guide further exploration of granite-hosted U deposits.

Research highlights► In the Taoshan U-ore district, the Daguzhai U-bearing granite and Huangpi U-barren granite are coeval at 154 ± 2 Ma. ► The Daguzhai and Huangpi granites show different major and trace element geochemical and Sr–Nd isotopic characteristics. ► The Daguzhai granite belongs to peraluminous S-type and the Huangpi belongs to fractioned I-type. ► The different magma sources controlled the different U contents in the two granites. ► Searching for granites with similar characteristics as Daguzhai is helpful for further exploration of uranium deposits in South China.