铅山—广丰晚中生代岩浆岩来源及与铀矿化关系

Source of the Late Mesozoic Magmatic Rock System and Its Relation to Uranium Mineralization in Yanshan—Guangfeng Area,Jiangxi Province

本文研究了铅山—广丰晚中生代岩浆岩来源及与铀矿化关系。本区晚中生代处于由燕山早期的挤压造山向新生代的拉张伸展过渡的构造环境,发育了一套过渡性的岩浆岩建造。早白垩世早期石溪组岩浆岩建造(130～120 Ma)为碱性流纹岩—英安岩—安山岩—玄武岩系列;早白垩世晚期周家店组的岩石组合(100～90 Ma)为酸性岩(花岗斑岩)—玄武岩,构成双峰式的岩浆岩建造,均属于同熔岩浆岩体系。赣杭构造—火山岩带铀矿床与本区深源碱性、偏碱性的高钾岩浆岩体系有着内在的必然联系,铀成岩—成矿受伸展构造系统控制。火山活动与随后的浅成、超浅成斑岩体活动在铀成矿中具有很重要的作用。

This paper discusses the source of the Early Cretaceous magmatic rock system and its relation to uranium mineralization in Yanshan—Guangfeng area. In tectonic environment, the area was transitioned from the compressed and orogenic tectonic environment in the early Mesozoic to tensile and extensional tectonic environment in the Cenozoic. In late Mesozoic, transitional magmatic rock geogeneration developed. The magmatic rock geogeneration of the early Early Cretaceous Shixi Formation (130～120 Ma) belongs to the alkali (rhyolite)-dacite-andesite-basalt series. The rock assemblage of the late Early Cretaceous Zhoujiadian Formation consists of acidic rocks (granite-porphyry) and basalt, belongs to a bimodal type of magmatic rock geogeneration, and they both belong to the syntectonic magma system. There are certain relationship between the uranium deposits in Jiangxi-Zhejiang tectonic volcanic rock belt and alkaline, less alkaline magmatic rock system which is deep-focus and rich in potassium in this area. Its diagenesis and uranium mineralization is controlled by extensional tectonic system. The volcanic activity and subsequent hypabyssal and super hypabyssal porphyry body activity play an important role in uranium mineralization.