准噶尔盆地西北缘下白垩统吐谷鲁群地质特征及砂岩型铀矿找矿方向

Geological Characteristics of the Lower Cretaceous Tugulu Group and Uranium Prospecting Direction in the Northwestern Margin of Junggar Basin

准噶尔盆地西北缘自燕山晚期以来构造相对稳定,下白垩统吐谷鲁群为一套厚层的三角洲沉积体系,下部(a、b段)在夏子街-德仑山地段发育较为连续的厚层砂体,近年来发现了层间氧化带,具有较好的铀成矿条件和找矿前景。文章梳理和分析了准噶尔盆地西北缘构造、岩性-岩相及后生蚀变等地质条件,认为德仑山地段为西北缘寻找砂岩型铀矿的首选地段,主攻层位为吐谷鲁群,层间氧化带尖灭部位或氧化带内有机质(或黄铁矿)富集部位为铀富集成矿和有利找矿突破的部位。

Tectonic setting in the northwestern margin of the Junggar has been relatively stable since Late Yanshan period and the delta sedimentary system was developed in the Lower Cretaceous Tugulu Group.In Xiazijie-Delunshan area,thick-layer sand body was deposited in the Member a and Member b of the Tugulu Group.In recent years,the interlayer oxidation zone has been found in the Tugulu Group,which has good uranium metallogenic conditions and prospecting prospects.Guided by the evaluation system of sandstone-type uranium deposits,this paper analyzed the structure,lithology-lithofacies and epigenetic alteration in the study area.It was considered that Delunshan area is the first choice for finding sandstone-type uranium deposits,the main target stratum is the Tugulu Group,and the favorable location for uranium mineralization and prospecting were the place where the interlayer oxidation zone pinch-out and rich organic matter(or pyrite)was developed in the oxidation zone.