【摘要】 二连盆地乌兰察布坳陷西部砂岩型铀矿勘查中新发现了深部层位的工业铀矿化,但其时代归属尚不明确。经沉积学和层序地层学研究发现,乌兰察布坳陷西部赛汉塔拉组发育三级层序A(赛汉塔拉组下段层序)和层序B(赛汉塔拉组上段层序)。在层序A中还可以划分出低位体系域(LST)、湖扩体系域(EST)和高位体系域(HST)。以往二连盆地砂岩型铀矿主要产于层序A的HST和层序B的LST;而经古生物、岩石地层和层序地层学对比研究发现,乌兰察布坳陷西部新发现的工业铀矿化产于层序A的LST。层序A的LST的成矿能力取决于含煤岩系还原介质和骨架砂体的规模。辫状河三角洲沉积体系中的辫状分流河道砂体是最有利的铀储层。沿富铀的卫境岩体形成近百米至千米间断发育的潜水-层间氧化带,成矿过程可分为早白垩世沉积期铀的预富集、晚白垩世至古近纪古新世成矿作用、古近纪始新世至第四纪保矿3个阶段,最终建立"断拗控砂体-反转控氧化-还原控矿体"三位一体成矿模式。将新发现的工业铀矿化层厘定为层序A的LST,拓展了二连盆地乌兰察布坳陷西部找矿前景。更多还原

【Abstract】 Industrial uranium mineralization in deep strata has been newly discovered during the exploration of sandstone-type uranium deposits in Western Wulanchabu Depression,Erlian Basin,but its age attribution is still unclear.Sedimentary and sequence stratigraphy studies show that three-stage sequence A(lower Seihantala sequence)and sequence B(upper Seihantala sequence)are developed in the Saihantala Formation in Western Ulanchabu Depression.Sequence A can also be divided into low system tract(LST),lake spreading system tract(EST)and high system tract(HST).In the past,sandstone-type uranium deposits in Erlian basin were mainly produced in HST of sequence A and LST of sequence B,while the newly discovered industrial uranium mineralization in the western part of Wulanchabu depression was found in LST of sequence A through the paleontological,lithostratigraphic and sequence stratigraphic comparative studies.The LST metallogenic ability of sequence A depends on the size of reducing medium and skeleton sand body of coal-bearing rock series.The braided distributary channel sand body in braided river delta sedimentary system is the most favorable uranium reservoir.Nearly 100 kilometers of intermittent phreatic-interlayer oxidation zone was formed along the uranium-rich satellite rocks.The uranium metallogenic process can be divided into three stages:the pre-enrichment of uranium during early Cretaceous sedimentary period,the metallogenic process from late Cretaceous to Paleogene Paleocene,and the preservation of uranium from Paleogene Eocene to Quaternary.Finally,a trinity metallogenic model of " fault-controlled sand body-reverse-controlled oxidation-reduction-controlled ore body" has been established in this paper.The newly discovered industrial uranium mineralization layer is defined as LST of sequence A,which expands prospecting prospects in the western part of Ulanchabu Depression,Erlian Basin.更多还原