鄂尔多斯盆地东北部侏罗系古河道中一种特殊的砂岩型铀矿床  

A special kind of sandstone-type uranium deposit related to Jurassic palaeochannel systems in the northeastern Ordos Basin,China

作　　者：李子颖[1] 焦养泉[2] 陈安平[3] 方锡珩[1] 夏毓亮[1] 张珂[4] 孙晔[1] 

机构地区：[1]核工业北京地质研究院,北京100029 [2]核工业208大队,内蒙古包头014010 [3]中国地质大学(武汉),湖北武汉430074 [4]中山大学,广东广州510275

出　　处：《世界核地质科学》2010年第1期62-62,共1页World Nuclear Geoscience

摘　　要：东胜砂岩型铀矿床是近几年在中国鄂尔多斯盆地东北部发现的一大型铀矿床。因其独特的特征而不同于其他普通砂岩型矿床,矿体一般受绿色砂岩和灰色砂岩之间的过渡带控制,而这两种砂岩目前都指示着还原地球化学环境。古氧化绿色砂岩主要由与油-气二次还原作用有关的绿泥石化和绿帘石化造成。从成因上讲,该矿床与普通砂岩型铀矿床不同,它有着更为复杂的成因,不仅经历了古氧化的成矿过程,而且还经历了油-气流体和热液流体的再改造。空间上,它与侏罗纪直罗组辫状古河道体系有关。较高品位的铀矿化带一般赋存在辫状河主河道与分支河道的分叉部位,所形成砂岩的不均匀性表明,其沉积相属于辫状河到辫状三角洲的过渡沉积体系。统计结果表明,中、细粒砂岩是铀矿化最有利的岩石类型。Dongsheng sandstone-type uranium deposit is a large one discovered in recent years in the northeastern Ordos Basin,China. It is a special kind of sandstone-type uranium deposit,different from other ordinary sandstone-type deposits because of its unique signatures. It is generally controlled by a transitional zone between greenish and grayish sandstones,both of those two kinds of sandstones now indicate reduced geochemical environments. The greenish color of the palaeo-oxidized sandstones mainly results from chloritization and epidotization related to oil and gas secondary reduction processes. The deposit genetically is different from ordinary sandstone uranium deposits,which is of more complex origin,undergoing not only palaeo-oxidization mineralization process,but also oil-gas fluid and hydrothermal reworking processes. It is spatially related to Jurassic Zhiluo Formation with braided palaeochannel systems. The uranium mineralization zone with higher grade usually exists in the branching area of the distributary channels of main braided streams,whose sandstone heterogeneity shows a transfer sedimentary facies from the braided stream sedimentary system to the braided delta sedimentary system. Statistical results show that medium and fine-grained sandstones are the most favorable rock types for uranium mineralization.

关 键 词：砂岩型铀矿床 分支河道 辫状河 鄂尔多斯盆地 

分 类 号：P619.14[天文地球—矿床学]