【作者】 郭宏伟；

【导师】 陈岳龙；

【作者基本信息】 中国地质大学（北京） ， 地球化学， 2014， 博士

【摘要】 正文：二连盆地不仅是重要的油气成藏区和聚煤区，也是砂岩型铀矿富集成矿区。本论文以外生后成砂岩型铀矿成矿理论为指导，在综合分析岩心、钻孔测井、地震以及其它物探、水文地质与水化学及铀矿床（点）等基础地质资料的基础上，运用层序地层、沉积体系分析等方法，结合实验分析测试结果，多学科综合研究相结合，对巴彦乌拉砂岩型铀矿富集形成的构造环境、赋矿层位的沉积相、砂体特征、氧化带发育特征与铀矿化特征、控矿因素进行了研宄。通过己发现铀矿床成矿条件深入剖析，建立了研究区层间氧化带砂岩型铀矿成矿模式。论文研宄取得了以下创新性成果和认识：1、研宄区铀矿体主要赋存在下白垩统赛汉组上段古河谷砂体中，赋矿岩性为多粒级砂岩组合体，包括砂质砾岩、中粗砂岩、中细砂岩、含粉砂质砂岩夹泥岩，但以砂质砾岩为主，非均质性强。目的层段砂岩岩石学特征以及空间分布规律表明，赋矿层位主要沉积微相类型为辨状河河道充填组合以及河道边缘组合，测井响应特征明显。2、铀矿体主要受古河谷砂体中发育的潜水-层间氧化带控制，氧化带平面分带性明显。矿体产于前锋线附近的灰色砂体中，矿体在平面上的展布与氧化带前锋线的展布方向基本一致。3、主矿体空间分布受古河谷展布形态控制。剖面上，矿体形态受潜水-层间氧化带前锋线控制有板状及卷状两种形态。根据矿石镜下鉴定结果，铀矿石主要有砂岩类和砾岩类两种。矿石矿物成分与围岩成分接近，但含较多黄铁矿、有机炭、粘土质等。主微量元素分析表明，矿石中SiO:、FeO、FeA、A1A、K20、_、TiO:.含量高，CaO、MgO、C02等有害组份含量低，微量元素Rb、Ba相对富集，而Sr相对亏损。4、对经铀镭平衡系数校正铀含量样品，应用全岩铀一铅等时线法，计算出巴彦乌拉铀矿床矿石的成矿年龄为44±5Ma，成矿时代约为古近纪始新世（E:)。经放射性照相、电子探针和扫描电镜等分析研宂，初步确认巴彦乌拉铀矿床矿石铀存在形式有三种：吸附态铀、铀矿物及含铀矿物，其中以吸附状态铀为主，六价态的铀比例较高。5、矿体及上下围岩中铼、硒、钼、钪、钒等伴生元素有富集现象，其中铼、硒、钪含量达到综合利用指标。铼与铀伴生产出，硒偏氧化一侧沉积，钪偏还原一侧富集。6、在氧化带、古水动力等控矿因素分析的基础上，提出了巴彦乌拉地区砂岩型铀矿床成因模式：该区铀矿基本产在早白垩世晚期的古河谷中，成矿贯穿河谷的形成、发展和变化的全过程。主要是后生成矿作用，即：来自补给区的含铀含氧水侧向渗入到河谷中，沿着泥岩隔水层中的透水砂岩径流，经与砂岩中的还原物质反应，使铀还原沉淀富集。此过程受古河谷“补一径一排”水动力条件、还原能力及次造山活动等控制。成矿过程可分为铀的预富集、成矿作用、后期保矿3个阶段。上述研宄成果和认识不仅对二连盆地砂岩型铀矿的勘探开发具有重要指导作用，而且对丰富国内砂岩型铀矿的成矿理论研究具有重要意义。更多还原

【Abstract】 Content: Erlian basin is an important reservoir of not only oil, gas and coal, but alsosandstone type uranium. This thesis is based on mineralization theory of exogenic epigeneticsandstone type uranium. A metallogenic model of interlayer oxidation zone sandstone typeuranium deposits has been established by comprehensive analysis and research such as basicgeological data，sequence stratigraphy, depositional system, test results, especially the studyof characteristics on the tectonic setitng, depositional facies, sand body, oxidation zone,mineralization, ore-controlling factors. The following results and knowledge have beendrawn in this paper:1，the uranium ore-bodies lie in ancient valley sandbodies of the upper section of Saihanformation, Lower Cretaceous Seires. The orebody lithology is multi-graded sandstoneassembly with strong inhomogeneity, including sandy conglomerate, medium-coarse grainedsandstone, mid-fine grained sandstone, silty sandstone interbedded mudstone, sandyconglomerate. And the sandy conglomerate is the main composition. Braided irverfilling-combination and channel edge-combination is the main sedimentary microfacies ofthe ore-bearing strata, and it has a distinguished feature of well log.2，the uranium deposits are controlled mainly by the phreatic-interlayer oxidation zonedeveloped in sandstone-bodies of ancient Valley. The oxidation zone has an obviouszonation in the plane. The orebodies lie in grey sandstone near the forward line of oxidationzone. And the distirbution of the orebody is consistent with the direction of the front line ofoxidation zone in plane.3, in profile, the shapes of the orebodies are tabular and rolling，which controlled byfront line of phreatic-interlayer oxidation zone. And the spatial distirbution of ore-bodies iscontrolled by the development of palaeo valley section. Two main types of uranium ore havebeen determined by the appraisal result of ore in microscope: sandstone-type-ores andconglomerate-type-ores. Composition of ore, which contains more pyrite, organic carbon,clay etc.，is similar to that of wall rock. The content of the major trace-elements, such asSiOa, FeO, Fe2〇3，AI2O3，K2O, Na20，T1O2is high in the ore，and the content of the harmfulcomponent, such as CaO, MgO, CO2is low. Relatively，the trace elements, such as Ba，Rb，Ba is enrichment, however, Sr is loss.4，the metallogenic age of Bayanwula uranium deposits is44土5Ma (Paleocene Eocene(E2))，which has been determined by whole rock U-Pb isochron method, and the uraniumcontent of ore sample has been corrected by the uranium-radium equilibrium coeiffcient. Theexisting forms of the uranium in the ore are: adsorbed, minerals, and beairng, which havebeen found by the methods of radiograph, electron probe and scanning electron microscope.Adsorbed uranium is the main form, and the proportion of six-valence uranium is higher.5，associated elements in the ore-body and surrounding rock, such as selenium, rhenium,molybdenum, vanadium, scandium, etc., are enrichment, and rhenium, selenium, scandiumcan be utilized comprehensively. Rhenium and uranium are symbiotic relationship, andselenium deposited close to the oxidation side, and scandium enriched close to the reductionside.6，the mentallogic model of sandstone type uranium deposits in Bayanwula area hasbeen established based on study of ore controlling factors, such as oxidation zone, ancienthydrodynamics: The uranium deposits lie in ancient valley of the late of the EarlyCretaceous; the epigenesist metallogenic process consisted of3stages, enrichment,mineralization and ore-conservation, ran through the whole process of the generics,development and change of the valley; oxygen-uranium-beairng water coming from rechargearea seeped through the valley from lateral side，and moved along permeablesandstone-bodies caught in mudstone aquicludes, and then, uranium was precipitated andenriched by the reaction on reduction material in sandstone. This process is controlled by hydrodynamics conditions of the ancient Valley, reducing power and orogenic activity.The conclusion and understanding of the study have not only significant guiding on theexploration and development of sandstone type uranium deposits in Erlian Basin, but alsogreat significance to perfect metallogenic theory of the sandstone type uranium deposits.更多还原