广东河源断裂带基性岩脉时代及其与铀成矿关系

Geochronology of Mafic Dikes in Heyuan Fault Zone,Guangdong Province and Its Relationship with Uranium Mineralization

为探索晚白垩世以来河源断裂带周边红盆内发育的众多的铀矿床与区内伸展构造的关系,本文对河源断裂带平远仁居辉绿玢岩、新丰下郑辉绿岩和黄沙坑辉绿岩进行了LA-ICP-MS锆石U-Pb定年,测试结果显示其加权年龄分别为154.3±1.6 Ma、85.7±2.0 Ma和148.6±4.1 Ma。仁居辉绿岩样品还包含2个古近纪年龄分别为49.5 Ma和52.4 Ma。结合华南及本地区的基性岩脉成因及年代学研究,认为本地区可能存在178 Ma、154~148 Ma、96~87 Ma、82~73 Ma、68~49 Ma五个伸展拉张阶段。燕山晚期多次酸性和基性岩浆活动的叠加,形成了多期、多阶段的铀矿化,其成矿作用时间从晚白垩世至古近纪。铀成矿与基性岩脉的侵入时间有很好的一致性,说明区内晚白垩世和古近纪红盆内发育的众多铀矿床与这些多阶段的伸展拉张有关。

In order to explore the relationship between the numerous uranium deposits in the red basin around the Heyuan fault zone and the extensional structures since the Late Cretaceous,the LA-ICP-MS zircon U-Pb dating of the Renju diabase-porphyry in Pingyuan,Xiazheng and Huangshakeng diabase-dikes in Heyuan fault zone,Guangdong Province,are present in this paper,and yields weighted ages of 154.3±1.6 Ma,85.7±2.0 Ma and 148.6±4.1 Ma,respectively.The sample of Renju yields two Paleogene ages of 49.5 Ma and 52.4 Ma.Combined with the previous study,five extensional and tensile stages of 178 Ma,154-148 Ma,96-87 Ma,82-73 Ma,and 68-49 Ma can be identified.The superposition of multiple magmatic activities leads to multi-stage uranium mineralization from Late Cretaceous to Paleogene in the Late Yanshanian.The uranium mineralization is consistency with the intrusion time of mafic dikes,which maybe indicate that the uranium deposits developed in the Late Cretaceous and Paleogene red basins are related to these multi-stage extensions.