In recent years, there have been important breakthroughs in the exploration for sandstone-hosted uranium (U) deposits in the Louzhuangzi district of the southern Junggar Basin. Between 2020 and 2023, a medium-sized sandstone-hosted uranium deposit production area was identified in the region. Only a few investigations have been conducted at the Louzhuangzi U deposit, including those analyzing its geological–tectonic evolution, basic geological features, hydrogeology, and ore-controlling factors. It is generally believed that uranium mineralization at the Louzhuangzi U deposit is controlled by a redox zone. Organic matter (referred to as OM hereafter) consisting of bitumen and carbonaceous debris is very common in the uranium ores (especially in high-grade ores) at the Louzhuangzi U deposit. However, the characteristics of the OM and its contribution to uranium’s mineralization have not been studied in detail. In this study, OM-rich U-ores, altered sandstone, and barren sandstone samples were collected for petrography, mineralogical, micro-spectroscopy, carbon, and sulfur isotope studies. The results of this study show that the distribution of U minerals and metal sulfides (pyrite, sphalerite, etc.) was strictly controlled by bitumen at the Louzhuangzi U deposit. The bitumen may have been formed by hydrocarbon-rich and U-rich ore-forming fluids, which were formed after hydrocarbon generation and expulsion in the underlying Jurassic coal-bearing source rocks. The fluids contained U, Zn, Fe, and other metal elements, which migrated together and then precipitated into the oxidized Toutunhe Formation sandstone through cracking and differentiation processes. Therefore, the results indicate that migrated hydrocarbons were involved in U mineralization, in addition to oxidation–reduction processes, in the Louzhuangzi district, south of the Junggar Basin (China).

Sandstone-type uranium deposits hold significant value and promise within China’s uranium resource portfolio, with the majority of these deposits found at the junctions of basins and mountains within Mesozoic and Cenozoic basins. The Kamust uranium mining area, located in the eastern part of the Junggar Basin, represents a significant recent discovery. Prior research on this deposit has been confined to two-dimensional analyses, which pose limitations for a comprehensive understanding of the deposit’s three-dimensional characteristics. To address the issue of uranium resource reserve expansion, this study employs 3D geological modeling and visualization techniques, guided by uranium deposit models and mineral prediction methods. First, a 3D model database of the Kamust uranium deposit was constructed, comprising drill holes, uranium ore bodies, ore-controlling structures, interlayer oxidation zones, and provenance areas. This model enables a transparent and visual representation of the spatial distribution of favorable mineralization horizons, structures, stratigraphy, and other predictive elements in the mining area. Second, based on the three-dimensional geological model, a mineral prediction model was established by summarizing the regional mineralization mechanisms, ore-controlling factors, and exploration indicators. Combined with big-data technology, this approach facilitated the quantitative analysis and extraction of ore-controlling factors, providing data support for the three-dimensional quantitative prediction of deep mineralization in the Kamust uranium deposit. Finally, using three-dimensional weights of evidence and three-dimensional information-quantity methods, comprehensive information analysis and quantitative prediction of deep mineralization were conducted. One prospective area was quantitatively delineated, located east of the Kalasay monocline, which has been well-validated in geological understanding. The research indicates that the area east of the Kalasay monocline in the Kamust mining district has significant exploration potential.

In this paper,the lithology-lithofacies characteristics,sedimentary characteristics,sand body morphology and plane distribution characteristics and sedimentary evolution of Jurassic in different epoch were researched in detail by the observation of a large number of borehole core,statistics on drilling and logging data and the analysis of the tectonic-sedimentary response of the basin.It was concluded that a set of coal-bearing coarse clastic sediments of braided river-braided river delta were developed in the sedimentary stage of Badaowan Formation of Jurassic in Kamusite.Sangonghe Formation was formed in the lake expansion epoch and developed fine-grained lacustrine deposits;Xishanyao Formation was a set of lacustrine coal-bearing clastic deposits;Toutunhe Formation was developed with a set of large lacustrine regressive lithologic-facies sequence,which was the sedimentary response to the lake-basin atrophy caused by regional tectonic uplift in Middle Jurassic.Three sedimentary formations favorable for sandstone-type uranium mineralization were developed in Jurassic strata from bottom to top,namely,the grey coal-bearing sedimentary formation at the bottom of the upper part of Badaowan Formation,the dark coal-rock formation of Xishanyao Formation and the primary grey sedimentary formation in the lower part of Toutunhe Formation.The sedimentary evolution of Jurassic determined the vertical lithologic-lithofacies combination characteristics and controlled the development horizon and sand body type for sandstone-type uranium mineralization.A series of sedimentary products of low stand system tract and high stand system tract were formed in the continuous lake regression-lake transgression in space,which is easy to form large skeleton sand bodies and resulting the formation of target horizons with good lithologic-lithofacies conditions and spatial configuration for uranium mineralization in Toutunhe Formation and Baodaowan Formation and Xishanyao Formation.

本文以汤原断陷古近系宝泉岭组为主要研究目标层位,开展了沉积岩石学特征、古沉积环境特征、沉积体系特征及层间氧化带发育特征等方面的研究,探讨了宝泉岭组发育特征及其对铀成矿作用的制约.研究认为:(1)宝泉岭组砂岩类型主要为长石岩屑杂砂岩和岩屑砂岩,岩石具典型的低成分成熟度、低结构成熟度特征,具有近物源搬运的特征;(2)古近系宝泉岭组沉积时期为陆相淡水环境,古气候表现为温湿—干热气候,地球化学环境表现为还原环境,具较高的还原容量,有利于铀元素的还原沉淀;(3)宝泉岭组发育扇三角洲相,主要砂体表现为分流河道和水下分流河道两类,其中分流河道砂体应作为研究区下一步砂岩型铀矿找矿的主攻砂体类型.

沉积盖层的原生沉积环境特征是其铀成矿条件分析的关键要素之一,文章在宏观沉积特征和微观岩石学特征基础上,结合岩石样品主微量元素分析、黏土矿物分析及古生物孢粉组合测试数据,综合分析了研究区上白垩统红砾山组红杂色碎屑建造的原生沉积环境.结果表明:1)红砾山组具有"下砂上泥、下黄上红、下粗上细"的沉积特征,岩石类型以岩屑长石砂岩为主,少量为长石岩屑砂岩和长石砂岩;2)CIA、ICV指数反映红砾山组沉积时期,物源区岩石遭受了较强的化学风化作用,并指示周缘物源区开始进入了构造活动期;3)一系列微量元素组合比值对比趋势指示红砾山组沉积时为陆相淡水、循环较为顺畅的富氧-次富氧环境,并且灰-灰白色砂岩的还原能力较为有限;4)红砾山组沉积时期,黏土矿物组合类型以蒙皂石+伊利石+绿泥石型为主,孢粉以裸子植物占优势,苔藓、蕨类植物孢子居次要位置,整体反映红砾山组沉积时期古地理环境属干旱-半干旱、较炎热、贫K+、碱性、强氧化、强蒸发条件下的河流相沉积.

沉积物的地球化学特征在沉积背景分析中起着非常重要的作用.以汤原断陷古近系宝泉岭组沉积时期泥岩和粉砂岩样品中微量元素含量为依据,选用对沉积介质环境反映比较敏感的锶(Sr)、钡(Ba)、铜(Cu)、钒(V)、镍(Ni)、铀(U)等微量元素指标,详细研究了目的层段岩石样品的元素地球化学特征,分析了研究区目标层中微量元素含量及其比值与沉积介质环境之间的对应关系,探讨了汤原断陷古近纪的沉积介质环境.结果表明:泥岩样品中Sr/Ba比值较低,反映陆相淡水环境;Sr/Cu比值较高,表明处于温湿-干热气候;V/(V+Ni)比值偏高,推断处于厌氧还原环境.总体来说,汤原断陷古近系宝泉岭沉积时期沉积环境主要为偏干热气候的陆相淡水还原环境.

三江盆地是我国黑龙江省东北部重要的中—新生代盆地.本文从三江盆地铀源条件、中—新生代构造演化、构造格局、中—新生代古气候演化、主要盖层沉积建造特征及后生蚀变特征等方面进行研究,以砂岩型铀矿成矿理论为指导,对三江盆地砂岩型铀矿成矿条件进行了综合分析,在此基础上对盆地找矿方向进行了探讨.研究认为:盆地西部具有较好的铀源条件,好于盆地其他地段;盆地中生代以来存在早白垩世末—晚白垩世早期和古近纪末—新近纪早期两期构造反转,在构造反转作用的控制下形成了盆地的主要找矿目标层下白垩统猴石沟组和古近系宝泉岭组含煤碎屑岩;猴石沟组、宝泉岭组及富锦组在盆地内发育有良好的地层结构和岩性岩相条件,同时在局部地区发育有氧化带,其是砂岩型铀矿找矿的重要线索.盆地砂岩型铀成矿条件总体较好,其中西部坳陷为重点工作区,猴石沟组和宝泉岭组为重点找矿层位.

以含矿目的层中侏罗统头屯河组为主要研究层位,通过岩性特征、岩石学特征、沉积构造、沉积体系分析及单井—联井剖面对比,从沉积学的角度解释喀木斯特地区铀矿化砂体特征.研究认为:喀木斯特地区头屯河时期发育两种沉积体系组合,一种是扇三角洲-湖泊沉积,一种是辫状河三角洲-湖泊沉积,并识别出扇三角洲平原、扇三角洲前缘、辫状河三角洲平原、辫状河三角洲前缘和滨浅湖5种亚相.镜下鉴定结果表明,含矿目的层头屯河组砂岩类型主要为长石岩屑砂岩,其次为长石岩屑杂砂岩、岩屑砂岩和岩屑长石砂岩,岩石具有典型的低成分成熟度、低结构成熟度特征.喀木斯特头屯河时期沉积相展布具有"北辫南扇"、"盆大水浅、河长扇短以及坡缓"等特点.头屯河组沉积相对喀木斯特地区铀矿化具有明显控制作用,主要体现在以下几个方面:①低位体系域的粗碎屑产物可为铀成矿提供较大的容矿空间;②辫状河道砂体是控制氧化带发育及矿体富集程度的主要因素,砂体的稳定连通为流体运移和成矿提供良好的条件;③特殊的大型"泥-砂-泥(煤)"结构有利于层间氧化带砂岩型铀矿化发育.

以鹤岗盆地早白垩世样品中微量元素测试结果为基础,选用对沉积介质环境反映比较敏感的锶(Sr)、钡(Ba)、铜(Cu)、铀(U)、钒(V)、镍(Ni)等微量元素指标,探讨了Sr/Ba、Sr/Cu、V/(V+Ni)、Cu/Zn、Th/U值与沉积环境的对应关系.分析结果表明:Sr/Ba比值较小,反映陆相淡水环境;Sr/Cu比值较高,表明处于干热气候;V/(V+Ni)比值较高,推断处于厌氧环境.总体来说,鹤岗盆地早白垩世猴石沟沉积时期沉积环境主要为偏干热气候的陆相淡水还原环境.

笔者等通过对鹤岗凹陷北部露头和钻孔资料的综合利用,结合少量的样品分析及薄片鉴定工作,对研究区下白垩统猴石沟组主要岩石学特征、沉积相类型及展布特征进行了综合研究,在此基础上,以砂岩型铀矿成矿理论为指导,对猴石沟组有利成矿砂体的沉积相类型进行了初步讨论.认为①猴石沟组砂体以长石岩屑砂岩和岩屑砂岩为主,主要为陆相淡水沉积环境,具较高的还原容量;②研究区内猴石沟组主要为扇三角洲沉积环境,并划分为辫状河道、漫滩沼泽、水下分流河道、河口坝、席状砂和分流间湾等6种微相;③猴石沟组沉辫状河道砂体可作为寻找潜水氧化带型砂岩型铀矿的重点类型,而水下分流河道砂体是作为寻找层间氧化带型砂岩型铀矿的主攻类型.

三江盆地位于黑龙江省东北部,是我国东北重要的产煤盆地之一,砂岩型铀矿地质工作程度较低.通过对三江盆地中东部绥滨坳陷和前进坳陷ZKJS1、ZKY1、ZKQX1及ZKQX2等9个钻孔岩心和测井资料的精细分析,认为绥滨坳陷主要发育辫状河三角洲和湖泊相,前进坳陷主要发育冲积扇(湿地扇)和湖泊相.绥滨坳陷城子河期主要发育辫状河三角洲沉积,至穆棱期向滨浅湖-半深湖过渡;前进坳陷宝泉岭时期主要发育冲积扇(湿地扇)-河流-湖泊沉积体系,至富锦期主要向河湖相砂泥岩沉积过渡.结合砂岩型铀矿成矿理论,从地层结构及砂体发育特征的角度讨论了三江盆地中东部砂岩型铀矿有利找矿层位,指出下白垩统城子河组和新近系富锦组发育的辫状河三角洲分支河道砂体厚度大、 分布稳定、 连续性强,渗性好,富含还原介质,发育良好"泥-砂-泥"地层结构,是研究区砂岩型铀矿有利找矿层位.

准噶尔盆地是我国重要的多能源矿产产出盆地之一.本文从盆地中新生代构造演化、沉积建造及古气候演化特征等基础砂岩型铀矿成矿地质背景入手,结合已知铀矿化发育层位、类型及分布范围特征,综合分析了准噶尔盆地中新生代构造沉积演化对砂岩型铀成矿的控制作用,认为:潮湿或半潮湿古气候环境有利于砂岩型铀矿含矿建造的发育;沉积建造类型控制铀矿化发育层位及容矿空间;构造活动期次及强度控制铀矿化发育时间、期次及保存与破坏.

以南堡凹陷南部缓坡带沙河街组和东营组样品中微量元素测试结果为基础，选用对沉积环境反映比较敏感的微量元素作为指标，分析研究区内地层中的微量元素含量及其比值与沉积环境之间的关系，进而探讨整个南堡凹陷古近系的沉积环境。结果表明，南堡凹陷古近系为微咸水相的淡水环境，沙河街组沉积时期的古盐度略高于东营组沉积时期；沙河街时期为偏干热环境，到东营组沉积时期，气候越来越温暖、潮湿；垂向上水体分层中等，形成不强的厌氧环境。