华南信江盆地砂岩型铀成矿控矿因素  

Ore-controlling Factors of the Sandstone-type Uranium Mineralizationin the Xinjiang Basin of South China

作　　者：张万良 李余亮 ZHANG Waniang;LI Yuiang(No270 Research Institute of Nuclear Industry,Nanchang,Jiangxi330200,China)

机构地区：[1]核工业二七〇研究所,江西南昌330200

出　　处：《现代地质》2024年第4期1109-1120,共12页Geoscience

基　　金：东华理工大学放射性地质与勘探技术国防重点学科实验室开放基金项目“华南红盆典型砂岩型铀矿床解剖-肖家砂岩型铀矿床铀矿化特征及成矿年龄研究”(2020RGET03);中国铀业有限公司—东华理工大学核资源与环境国家重点实验室联合创新基金(NRE2021-08)。

摘　　要：华南盆地群中的砂岩铀矿,是我国砂岩型铀矿的组成部分。北方砂岩型铀矿的成因研究取得了重要进展,而华南砂岩型铀矿的成因探索,多停留在矿床研究的描述阶段,这无疑是砂岩铀矿成因研究的薄弱环节。江西信江盆地发现肖家砂岩型铀矿床和多个砂岩型铀矿化点,是华南产铀红盆的代表性盆地。本文以信江盆地为例,通过资料二次开发、野外调查、镜下观察、微量元素分析,对信江盆地砂岩铀矿化的成矿特征和控矿因素进行研究。研究表明,信江盆地砂岩铀矿化主要产于上白垩统茅店组、周田组、河口组、塘边组红层所夹的“灰色层”中,含矿岩层的颜色呈灰色、灰白色、灰绿色、青灰色,岩性有砾岩、砂质砾岩、砂岩、粉砂岩、粉砂质泥岩等,矿化对层位和岩性的选择性不明显;空间上,砂岩铀矿化主要位于信江盆地中西端,围绕盆地深部下白垩统冷水坞组烃源岩上方或近外围分布,矿化强度与岩石中的有机质含量有关。分析认为,砂岩铀矿化受多种因素控制:(1)盆地坳陷区的烃源岩控制成矿物质来源;(2)红色层所夹的“灰色层”控制铀矿化的范围;(3)背斜构造轴部控制铀矿体的集中产出;(4)断层构造在新构造期的活动控制矿床的定位。成矿过程简要归纳为,盆地深部烃源岩中的铀等元素,因断层活动而活化,沿断层迁移到浅部背斜轴部附近的岩层或张性裂隙(破碎带)中的深部还原性成矿流体,当进入到浅部较氧化的环境时,铀酰有机络合物解离,铀等元素因自身还原剂作用而沉淀下来。Sandstone uranium deposits in the basins of South China are integral to China's sandstone-type urani-um deposits.Significant progress has been made in genetic research on sandstone-type uranium deposits in North China,while research on sandstone-type uranium deposits in South China remains predominantly descrip-tive,representing a critical gap in uranium genesis studies.The Xinjiang Basin in Jiangxi is a representative uranium-rich basin in South China,where Xiaojia sandstone-type and multiple sandstone-type uranium minerali-zation have been discovered.This study takes Xinjiang Basin as an example to investigate the ore-forming characteristics and controlling factors of sandstone-type uranium deposits in South China.It aims to perform comparative studies on ore-forming mechanisms and provide a theoretical basis for understanding sandstone-type uranium mineralization in China through literature review,field surveys,microscopic observations,and trace el-ement analysis.The results indicate that uranium mineralization in the Xinjiang Basin primarily occurs in the grey layers sandwiched between the red layers of the Upper Cretaceous Maodian,Zhoutian,Hekou,and Tang-bian Formations.The ore-bearing rocks include grey,grey-white,grey-green,bluish-grey conglomerates,sand-stone conglomerates,sandstones,silty sandstones,and silty mudstones.The selectivity of mineralization based on stratigraphic and lithological characteristics is not significant.Spatially,sandstone uranium mineralization is primarily located at the central and western ends of the Xinjiang Basin,near the deep-seated source rock of the Lower Cretaceous Lengshuiwu Formation or its periphery.The intensity of mineralization correlates with the or-ganic matter content in the rocks.It is concluded that sandstone uranium mineralization is controlled by multiple factors:(1)Rocks in basin depression areas control the sources of ore-forming materials;(2)Grey layers sandwiched between red layers determine the extent of uranium mineralization;(3)Anticline structures'axe

关 键 词：砂岩铀矿 灰色层 新构造活动 信江盆地 

分 类 号：P588.212.3[天文地球—岩石学] P619.14[天文地球—地质学]