中国北西部地区砂岩型铀矿含矿建造及找矿前景

本文在分析中国北西部地区大地构造背景的基础上,依据孕育中、新生代沉积盆地形成的基底构造性质,将其划分为板内陆台型、板缘褶皱造山带型和板缘过渡带型3种类型,板缘褶皱造山带型又进一步划分为洋侧造山带型和陆侧造山带型两个亚类。砂岩型铀矿的产出盆地与盆地所处的构造背景和构造类型有关,砂岩型铀矿产出盆地主要为板缘褶皱造山带型,其次为板内陆台型。砂岩型铀矿对盆地沉积建造类型具有明显的选择性,其原始沉积均为一套温湿气候条件下形成的灰色层,其岩石原生地球化学类型为黑色或灰色。中国北西部地区中新生代盆地形成可地浸的砂岩型铀矿的找矿层位或含矿建造主要为中、下侏罗统(J1-2)和上白垩统(K2),其次为下白垩统(K1),其他地质时期地层内铀矿床分布零星,成矿潜力很小。

The ore-bearing formation and prespecting forground ofsandstone ore in west-northern China

Based on analysis of geotectonic settings in northwestern China, and Mesozoic and Cenozoic sedimentary basin formation, this study divided this area into three tectonic types, intraplate platform, plate margin fold orogenic belt, and plate margin intermediate zone types. The plate margin fold orogenic belt can be further divided into two sub-types: ocean lean fold orogenic belt and continent lean fold orogenic belt. The basins hosting sandstone-type uranium deposit is closely related to structural settings of the basin and its type. Sandstone-type uranium ores occur mainly in plate margin fold orogenic belt type basins, with minor in intraplate platform type basins. The sandstone-type uranium ore have obvious selectivity to sedimentary formation type of the basin: its primary deposition is one grey rock layer formed under warm-damp climate condition. The Mesozoic and Cenozoic sedimentary basins in northwestern China can form sequences which contain sandstone-type uranium ores or ore-bearing formations are mainly Mid-Lower Jurassic System (J1-2) and Upper Cretaceous System (K2), with minor in Lower Cretaceous System (K1). The strata formed at other periods contain sparsely-distributed uranium prospects and have low exploration potential.