Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China)rnThe 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 = l2), 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.%大富足花岗岩体位于江西和福建的交界处,与铀成矿关系密切.通过激光剥蚀-多接收器电感耦合等离子体质谱(LA-MC-ICPMS)锆石U-Pb定年技术对大富足岩体进行了精确的年龄测定,获得岩体的中粗粒斑状黑云母(二长)花岗岩和中细粒含斑黑云母花岗岩年龄分别为(233.4±1.6)Ma(MSWD=0.30,n=13)和(233.1±1.6)Ma(MSWD=0.48,n=12),表明岩体形成于华南印支期花岗质岩浆活动第一阶段末期.大富足岩体属高钾钙碱性系列,具有相对低含量的SiO2和较高含量的Al2O3及ACNK值(1.12～1.36),并富含黑云母、白云母等富铝矿物,显示大富足岩体为典型的强过铝质S型花岗岩,暗示其形成于同碰撞挤压背景,是富含泥质成分变质沉积岩的部分熔融的结果.岩体具有较高的U、Th含量,独立晶质铀矿物和活动铀浸出率,暗示大富足岩体具有良好的铀成矿潜力.
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