潜水层间氧化带砂岩型铀矿特征与成矿模式——以滇西地区山间盆地为例

文章在收集整理龙川江盆地已有的1200个钻孔资料及9个施工钻孔资料的基础上,编制了岩性_岩相_地球化学剖面图58张,研究了盆地内砂岩型铀矿基本特征与成矿模式,并对不同构造部位矿体的定位模式进行了探讨。认为发育于造山带内部的小型山间盆地,由于盆地规模小,物源丰富,砂体发育厚度大,再加上地层时代新,后生氧化作用发育不充分,氧化带发育部位上、下翼有部分砂体不能被完全氧化。典型的潜水层间氧化带除具有与层间氧化带相似的舌状体前锋氧化还原界面外,在舌状体翼部亦形成上、下翼氧化还原界面,从而发育氧化带前锋与上、下翼3个板状或透镜状铀矿体,既不同于定位于层间氧化带前锋部位氧化还原界面附近的卷状铀矿体,也与定位于潜水氧化带底部氧化还原界面附近的层状、似层状铀矿体有所差异。

Characteristics and metallogenic models of phreatic interlayer oxidation zone sandstone-type uranium deposits: Case study of intermontane basins in Western Yunnan Province

There exist abundant uranium resources in Cenozoic basins of western Yunnan. These basins, with rich potential in prospecting for sandstone_type uranium deposits, constitute one of the important sandstone_type ura_ nium ore belts in China. The authors collected data from 1?200 previous boreholes, arranged 9 drilling holes, compiled 58 lithologic_lithofacies_geochemical profiles, studied characteristics and metallogenic models of sandstone_type uranium deposits, and investigated the locating models of uranium ore bodies at different tectonic positions in Longchuanjiang basin. It is concluded that the small_size intermontane basins developed within the orogenic belt, due to their abundant material sources, thick sand body, and relatively young strata, were only subjected to insufficient epigenetic oxidation, which has led to the incomplete oxidation of some sand bodies in the upper and lower limbs within the well_developed phreatic interlayer oxidation zone. Besides the tongue_like front oxidation_reduction interface similar to the interlayer oxidation zone, the oxidation_reduction interface is also developed in the upper and lower limbs within the typical phreatic interlayer oxidation zone. Three planar or lenticular uranium ore bodies are therefore developed in tongue_like upper and lower limbs along the interface of phreatic interlayer oxidation zone. These ore bodies are neither similar to the curly uranium ore bodies located in the front position near the oxidation_reduction interface of the interlayer oxidation zone, nor to the stratiform and stratoid uranium ore bodies located at the bottom of the phreatic oxidation belt near the oxidation_reduction interface of the phreatic oxidation zone.