准噶尔盆地中新生代砂岩型铀矿地层沉积特征与产铀远景预测

分析准噶尔盆地周缘中新生代的地层结构、含铀"泥-砂-泥"结构、含铀沉积类型及展布特征,认为垂向上叠置的湖退进积-湖进退积组合所形成的"泥-砂-泥"结构为大尺度上定位砂岩型铀成矿的有利地层结构,其中低位体系域(湖进退积)形成的辫状河-辫状河三角洲沉积是盆地砂岩型铀矿最为有利的沉积相带。主物源、转换带以及相带的变化进一步控制了砂岩型铀成矿的有利区分布:(1)原生灰色(还原)沉积地层中有利砂体分布往往受到主物源以及构造转换带的影响,主物源方向的河道砂体及构造转换带处的富砂区域是砂岩型铀矿主要的远景区域;(2)杂色沉积地层中的有利砂体分布主要受局部沉积环境变化的影响,有利砂体多发育在局部沉积相带突变(砂岩层有机质含量增加)的区域。

Sedimentary features and metallogenetic prospect prediction of Meso-Cenozoic sandstone-type uranium deposit in Junggar Basin

Through the analysis of stratigraphic structure,uranium hosting mud-sand-mud assemblage,uranium hosting sedimentary type and distribution in the Meso-Cenozoic around the Junggar Basin,the authors suggest that the vertical superimposition of the lacustrine regressive progradation and transgressive retrogradation produce favorable large sale mud-sand-mud assemblage, of which the low stand system tract (transgressive retrogradation) braided river and braided river delta are the most favorable sedimentary facies zones for sand-type uranium mineralization. Main provenance, transfer zone and facies belt variations further control favourable area distribution of sandstone-type uranium deposit:①the favorable sand body distribution in primary grey(reduction) strata is affected by main provenance and transfer zone, channel sand body in the main provenance direction and sand-rich area in transfer zone are the main prospects of sandstone-type uranium deposit; ②the favorable sand body distribution in variegated strata is affected by local sedimentary environment change, the favorable sand body is developed in the area where the sedimentary facies belt changes (organic matter content increases in sand body).