Zircon U-Pb Age, Tectonic Setting and Ore Potentiality of the Dafuzu Uranium-bearing Rock Mass in the Southeastern Jiangxi Province

The Dafuzu rock mass is located at the junction of Jiangxi province and Fujian province, and is closely related to uranium mineralization. In this paper, based on field surveys, we investigate the rock forming time of medium-coarse porphyritic biotite monzonitic granite and fine-grained biotite granite by Laser Ablation-Multicollector Inductively Coupled Plasma-Mass Spectrometry (LA-MC-ICPMS) zircon U-Pb dating, and determine the age as (233.4±1.6) Ma with MSWD=0.30 (n=13) and (233.1±1.6) Ma with MSWD=0.48 (n=12), respectively. These ages show that the Dafuzu rock mass belongs to products of the first stage of Indosinian granitic magmatic activity. Combining previous studies, Dafuzu granite rich in Al-rich minerals such as biotite and muscovite and characterized by relatively low SiO₂ and high Al₂O₃, peraluminous (A/CNK=1.12-1.36), suggest that the Dafuzu granite was probably formed in the syn-orogenic tectonic setting and may be derived from sedimentary rocks consisting of ancient crustal materials. In addition, the Dafuzu rock mass is characterized as having a high U and Th content with a leaching rate of mobile uranium and independent of micro-grained uraninites, suggesting a great uranium metallogenetic potential.