摘要
利用野外地质调研、岩心观察描述及镜下薄片、光片鉴定与定量统计结果,将鄂尔多斯盆地东胜地区中侏罗统直罗组含铀砂岩划分为氧化带黄褐色—紫红色砂岩、灰绿色蚀变砂岩、原生含矿带灰色砂岩及浅灰色—灰白色“漂白”砂岩4种类型。砂岩中的火成岩和泥岩岩屑可能是铀的来源之一。铀矿化是成岩后生阶段介质条件改变的产物,受氧化-还原界面的控制。铀的形成主要与天然气的运移和逸散有关,也可能与后生阶段的热液活动有关。砂岩中次生锆石与粒间绿泥石、蒙脱石胶结物和黄铁矿的密切伴生及其吸附铀的α径迹等特征表明,其形成与铀的富集存在成因上的联系。部分长石碎屑被高岭石替代和早期碳酸盐胶结物的溶解使一部分锶流失,这是造成“漂白”砂岩中低锶含量的主要原因。
The uranium-bearing sandstones in Dongsheng area were basically classified into four types including yellowish brown-red sandstones in the oxidation zone, gray sandstones and altered grayish green sandstones in the primary ore zone, and light gray-grayish white bleaching sandstones by using the data of field geological survey, observation and description of drilling cores, identification and quantitative statistics of thin sections and polished sections under microscope. The igneous and mudstone fragments in the sandstones were attributed to the uranium resources. Uranium mineralization was controlled by the oxidation-reduction interface and occurred under the medium condition changing from acidic oxidation to alkaline reduction during diagenesis and epigenesis periods. Generation of uranium was closely related to migration and escaping of natural gas and may be also relevant to hydrothermal solution activities during epigenesis period. Secondary or regenerated zircons closely coexisted with the intergranular smectite and chlorite cements and micro pyrite, which show a trace of absorbed uranium. It implies that formation of these zircons may be related with uranium enrichment in origin. Part of the feldspar fragments replaced by kaolinite and dissolution of early carbonate cements resulted in loss of strontium is the main reason for the bleaching sandstones with low content of strontium.
出处
《石油学报》
EI
CAS
CSCD
北大核心
2005年第4期39-45,49,共8页
Acta Petrolei Sinica
基金
国家重点基础研究发展计划(973)项目"多种能源矿产共存成藏(矿)机理与富集分布规律"(2003CB214603)。
关键词
含铀矿砂岩
成岩作用
成岩环境
介质条件
铀矿成因机制
鄂尔多斯盆地
uranium-bearing sandstones
diagenesis
diagenetic environment
medium condition
uranium mineralization mechanism
Ordos Basin