内蒙古二连裂谷盆地“同盆多类型"铀矿床组合与找矿方向

自20世纪90年代开始,核工业部门在二连盆地中开展了广泛的铀矿找矿工作,在乌兰察布和马尼特2个坳陷中发现了多个不同类型的铀矿床。文章从裂谷盆地的发展演化入手,分析了二连盆地构造演化阶段和各阶段中沉积充填类型特征。根据构造-沉积-含铀含氧流体在时空上的耦合作用及其结果,初步建立了早白垩世早期腾格尔组中含煤(砂)泥岩型道尔苏矿床、侧向氧化和垂向氧化形成的赛汉组中古河道砂岩型巴彦乌拉和赛汉高毕矿床、以及晚白垩世二连组中由蒸发沉积-成岩-热流体改造形成的努和廷矿床等"同盆多类型"铀矿成矿模型。同时,依据铀矿床成矿地质作用和地质特征,以及不同类型铀矿化发育的空间部位特点,指出了"同盆多类型"铀矿在盆地凹陷中发育的有利空间位置,总结了裂谷盆地不同阶段的"同盆多类型"铀矿床组合规律,为在东北亚地区类似盆地中找寻相似的铀矿床组合指明了方向。     

沉积、成岩与铀成矿:中国砂岩型铀矿研究的创新发现与认知挑战

21世纪,中国在砂岩型铀矿勘查领域获得了前所未有的辉煌成就.砂岩型铀矿产出于沉积盆地,铀矿的形成必须经历由沉积埋藏到抬升成矿两个重要的演化阶段.其中,在抬升成矿阶段,大气降水和氧化-还原作用的参与和约束是最显著的成矿特征.显然,这是一种典型的表生成岩作用的产物,是铀储层复杂成岩序列中的重要一环,隶属于“外生成矿”的范畴.虽然,砂岩型铀矿的成矿作用遵循氧化还原与铀变价的普遍机理,但是特殊的沉积背景却导致了铀成矿作用的多样性和地区的专属性.一些由沉积作用、沉积环境和古气候造就的关键控矿要素,能够从“基因”上直接影响表生成岩阶段的铀成矿作用,由沉积、成岩到铀成矿是一个具有成因联系的地质过程,而盆山耦合机制始终是其最根本的原始驱动力.随着对铀成矿作用细节行为研究的深入,一些创新发现不断地冲击着以往固有的认识,诸如碳质碎屑与铀成矿的相互作用、黄铁矿复杂而有序的演化习性、碳酸盐胶结物与铀成矿的共生叠置、敏感矿物的流体示踪、铀储层非均质性制约下的铀成矿机理、双重还原介质制矿模型、铀成矿的复合地球化学障等.还有一些研究对传统地质学理论提出了认知挑战,诸如,铀储层开放成岩环境中碳质碎屑的“碳化作用机理”、黄铁矿溶蚀或者生长界面上的铀沉淀化学动力机制、干旱沉积背景的铀成矿机理等.同时,铀成矿机理和普遍规律的研究,也为砂岩型铀矿的衰变地质效应研究和盆地铀资源的系统探索奠定了良好的地质基础.相信,针对沉积盆地整装的系统的成矿机理与成因联系研究,必将释放巨大的盆地铀资源潜力和矿床产能,在进一步丰富铀成矿理论的同时助力实现“双碳目标”.      

二连盆地砂岩型铀矿找矿方向探讨

文章通过岩性和铀含量分析,进一步确定了二连盆地主要找矿目的层为赛汉组上段(K1s2),重要找矿层位为赛汉组下段(K1s1),探索找矿层位为腾格尔组上段(K1t2),兼顾找矿层位为二连组(K2e)。从铀源-构造-建造-改造全要素进行了铀成矿条件整体分析,认为赛汉组上段主要沿各凹陷长轴方向发育古河谷,形成古河谷型铀矿化,受古河谷、凹陷中央低洼构造、后生蚀变控制;赛汉组下段和腾格尔组上段主要沿盆缘斜坡带发育扇三角洲沉积体系,形成潜水-层间氧化带型铀矿化,受铀源、三角洲沉积体系、后生蚀变控制;二连组主要在额仁淖尔凹陷中部发育湖泊沉积体系,形成沉积成岩型铀矿化,受铀源、二连期最大湖泛面控制;二连盆地发育大规模铀成矿作用,大致可划分为三期:99~78 Ma为沉积成岩期,67~37 Ma为后生作用主成矿期,25~8 Ma为后生叠加改造期。在此基础上,分层位按类型指明了找矿方向,总体认为二连盆地找矿工作应以乌兰察布和马尼特坳陷为重点,辐射川井、腾格尔和乌尼特三大坳陷,统筹兼顾、合理部署,具有很大找矿潜力。     

二连盆地努和廷铀矿床成矿作用及成矿模式

通过研究努和廷铀矿床地质特征、成矿作用及地球化学特征,认为努和廷矿床为同生沉积后生改造型铀矿床。晚白垩世二连期湖泊发育区控制了矿床定位。矿床成矿作用经历了同生沉积成矿、后生改造和表生作用3个阶段,成矿年龄为85Ma、（41±5）Ma和6～13Ma。在总结矿床成矿地质特征、成矿作用及地球化学特征基础上,建立了努和廷铀矿床成矿模式。     

微生物、有机质、油气与砂岩型铀矿①

统计表明,世界上已知重要的砂岩型铀矿床的含矿主岩不同程度地含有机质、微生物或油气。对十红滩矿床、努和廷矿床及512矿床进行有机岩石学、有机地球化学、铀与有机碳相关关系分析等研究结果表明,微生物、有机质或油气在砂岩型铀矿成矿的过程中起了重要的作用。     

巴音戈壁盆地塔木素铀矿床含矿砂岩成岩作用类型、演化序列及其对铀成矿的约束

勘查和研究发现部分砂岩型铀矿床中不仅有表生氧化流体作用还存在深部流体的参与,这类砂岩型铀矿床蚀变类型多样且成因复杂.塔木素砂岩型铀矿表生流体和深部流体活动都很明显,砂岩普遍固结且后生蚀变类型独特,因此,恢复成岩成矿事件及其演化过程,对揭示铀沉淀富集机理至关重要.本文通过镜下鉴定、电子探针、扫描电镜分析等,系统研究了塔木素矿床含矿砂岩成岩作用特征与后生蚀变矿物生成序列,重塑了成岩成矿事件的演化过程.研究结果显示,塔木素矿床砂岩中压实作用较弱而胶结作用很强,重结晶作用普遍,是造成目的层致密的主要原因,赤铁矿、褐铁矿化、碳酸盐化、石膏化是该地区主要的胶结类型.将该地区的成岩演化划分为沉积-早成岩阶段、早期氧化流体作用阶段、热流体改造阶段和晚期氧化流体弱改造阶段.成岩环境由弱碱性向酸性环境转变的过程中的氧化还原过渡部位是造成铀沉淀的关键,大规模的氧化作用是矿床形成的基础,后期热流体活动对早期形成的低品位铀矿石进行叠加改造,是成矿的关键环节.     

微生物、有机质、油气与砂岩型铀矿

统计表明，世界上已知重要的砂岩型铀矿床的含矿主岩不同程度地含有机质、微生物或油气。对十红滩矿床、努和廷矿床及512矿床进行有机岩石学、有机地球化学、铀与有机碳相关关系分析等研究结果表明，微生物、有机质或油气在砂岩型铀矿成矿的过程中起了重要的作用。     

内蒙古二连盆地哈达图砂岩铀矿渗出铀成矿作用

[研究目的]哈达图铀矿床是产于二连盆地下白垩统赛汉组上段的一个特大型砂岩型铀矿床，其与传统砂岩铀矿特点不同，矿体呈多层板状，控矿灰色砂体具“两黄夹一灰”特征，传统的渗入（潜水氧化、层间氧化）砂岩型铀成矿理论难以解释，阐明其成因和控矿要素对创新砂岩铀成矿理论与红杂色砂岩中铀矿找矿均具有重大意义。[研究方法]采用野外和室内、宏观和微观相结合，主要包括野外观察、区域地质、构造学、沉积学、岩石学、矿物学、地球化学（元素、有机、同位素）、地震解释和铀矿床学等方法。[研究成果]阐明了矿床矿体、控矿灰色砂体和矿化特征，指出研究区红杂色建造赛汉组上段、二连组和伊尔丁曼哈组为原生氧化建造成因，主含矿层赛汉组上段控矿灰色砂体是深部还原性流体对其再还原的结果，主要受连通深部的断裂构造及相关河道或不整合面控制，属后生改造成因，从成矿铀源、深部渗出流体的形成、铀的迁移和沉淀阐述了砂岩渗出铀成矿作用机制，提出哈达图砂岩铀矿床主要是渗出铀成矿作用形成，建立了相应的渗出铀成矿模式。[结论]发现揭示了红杂色砂岩形成砂岩铀矿一种新的铀成矿作用——渗出铀成矿作用，并由此提出了在红杂色沉积建造中寻找砂岩铀矿“上红下黑、上下连通、红中找灰、灰中找矿”预测评价的新思路，指出针对红杂色沉积建造砂岩铀矿找矿新层位，在找矿空间上可由盆缘拓展到盆中、由浅部拓展到深部。创新点：阐明控矿灰色砂体是深部还原性流体再还原的结果，属后生改造成因；提出了红杂色砂岩形成砂岩铀矿新的渗出铀成矿作用，建立了哈达图砂岩铀矿渗出铀成矿模式；提出了在红杂色沉积建造中寻找砂岩铀矿预测评价的新思路。     

Multistage Enrichment of the Sawafuqi Uranium Deposit: New Insights into Sandstone-hosted Uranium Deposits in the Intramontane Basins of Tian Shan, China

Meso-Cenozoic intracontinental orogenic processes in the Tian Shan orogenic belt have significant effect on the sandstone-hosted uranium deposits in the intramontane basins and those adjacent to the orogen. The Sawafuqi uranium deposit, which is located in the South Tian Shan orogenic belt, is investigated to reveal the relationships between uranium mineralization and orogenies. Recent exploration results show that the Sawafuqi uranium deposit has tabular, stratiform, quasi-stratiform, and lens-like orebodies and various geological characteristics different from typical interlayer oxidation zone sandstone-hosted uranium deposits. Systematic studies of ore samples from the Sawafuqi uranium deposit using a variety of techniques, including thin section observation, α-track radiograph, electron microprobe and scanning electron microscope, suggest that uranium mineralization is closely related to pyrite and organic matter. Mineralization-related alterations in the host rocks are mainly silicification and argillation including kaolinite, illite(and illite-smectite mixed layer) and chlorite. Tree stages of mineralization were identified in the Sawafuqi uranium deposit:(i) uranium-bearing detritus and synsedimentary initial pre-enrichment;(ii) interlayer oxidization zone uranium mineralization; and(iii) vein-type uranium mineralization. The synsedimentary uranium pre-enrichment represents an early uranium enrichment in the Sawafuqi uranium deposit, and interlayer oxidation zone uranium mineralization formed the main orebodies, which are superimposed by the vein-type uranium mineralization. Combining the results of this study with previous studies on the Meso-Cenozoic orogenies of South Tian Shan, it is proposed that the synsedimentary uranium pre-enrichment of the Sawafuqi uranium deposit was caused by Triassic Tian Shan uplift, and the interlayer oxidation zone uranium mineralization occurred during the Eocence-Oligocene period, when tectonism was relatively quiet, whereas the vein-type uranium mineralization took place in relation to the strong orogeny of South Tian Shan since Miocene.     

Sedimentology,stratigraphy and palynological occurrences of the late Cretaceous Erlian Formation,Erlian Basin,Inner Mongolia,People's Republic of China

The Erlian Basin is one of the non-marine Cretaceous basins of north-east China that developed during the late Mesozoic continental extension in eastern Asia. This basin experienced two major tectonic events: (i) a syn-rift stage that was dominated by a fluvial–lacustrine depositional environment and (ii) a post-rift stage that was dominated by a fluvial environment. A new sedimentological study performed on Erlian Formation drill cores has led to the determination of an architectural model and to the subsequent characterisation of the stratigraphic evolution of this sedimentary unit during the late Cretaceous. The palynological occurrences that were identified in samples provided a possible stratigraphical age for the Erlian Formation.Sediments of the Erlian Formation occur at the top of the Cretaceous stratigraphic column of the Erlian Basin and were deposited during the post-rift stage. Facies architecture and the ideal succession of facies that were identified for this formation exhibit two different members, both dominated by a fluvial depositional environment: (i) the lower member, which is dominated by channels of a braided river system and (ii) the upper member, which is dominated by overbank deposits. The lower member expresses a tectonically induced uplift as indicated by channels clustering under negative accommodation, whereas a period of stratigraphic base-level rise that is associated with an increase of accommodation is identified in the upper member. Therefore the Erlian Formation highlights an alternation of short uplifts that were dominated by braided fluvial channel deposits with periods of stratigraphic base-level rise that were dominated by overbank deposits. This sedimentological architecture has significant metallogenic implications for the origin of confined permeable sandstone layers, which represent adequate host-rocks for roll front-type uranium deposits.The palynological assemblage Exesipollenites, Ulmipollenites/Ulmoideipites, Buttinia and Momipites that were recognised in two samples of the Erlian Formation has revealed a post-late Campanian age therefore more likely indicating a late Cretaceous age of deposition for the sediments of the Erlian Formation.     

鄂尔多斯盆地东北部塔然高勒地区还原介质对砂岩型铀矿的控制

为明确鄂尔多斯盆地塔然高勒地区直罗组、延安组地层中煤、黄铁矿等还原介质与砂岩型铀矿的共存关系,选取直罗组含矿砂体及其中的黄铁矿、炭屑以及延安组煤层等为研究对象,综合利用钻孔编录、显微镜和电子探针分析等手段开展研究。结果表明,研究区铀矿体与延安组煤层、直罗组炭屑具有空间和成因上的关联,延安组煤层为铀的沉淀提供了大量的还原剂,而直罗组炭屑里的腐植酸对铀酰离子起到吸附和络合的作用;铀石是该区最主要的铀矿物类型,其与莓球状黄铁矿、蚀变黄铁矿、胶状黄铁矿、钛铁矿、白钛石伴生关系明显;有机质、黄铁矿等还原介质的含量及空间分布可以作为铀成矿的指示标志。     

松辽盆地南部钱家店铀矿床后生蚀变作用及其对铀成矿的约束

目前对松辽盆地南部钱家店铀矿床成因的认识存在明显争议.本文利用偏光显微镜、扫描电镜、XRD等分析测试方法对该矿床后生蚀变作用进行了系统的研究,发现该矿床不同类型砂岩中矿物蚀变作用类型有:赤铁矿化、褐铁矿化、黄铁矿化、粘土化、碳酸盐化和铀矿化,其中黄铁矿化包括胶状黄铁矿化、草莓状黄铁矿化和粒状黄铁矿化,粘土化主要包括水云母化、高岭石化和伊利石化,碳酸盐化包括方解石化、铁白云石化和菱铁矿化.红色砂岩和黄色砂岩以赤铁矿化、褐铁矿化、水云母化、高岭石化、伊利石化和方解石化为主,但黄色砂岩中赤铁矿化、褐铁矿化及水云母化程度略低;灰色不含矿砂岩以微弱赤铁矿化、黄铁矿化、高岭石化、伊利石化、铁白云石化和菱铁矿化为主;灰色含矿砂岩中以黄铁矿化、高岭石化、伊利石化、铁白云石化、铀矿化和菱铁矿化为主;原生灰色砂岩以黄铁矿化和菱铁矿化为主.钱家店铀矿床演化历史和矿物之间的穿插关系分析显示,成岩期矿物蚀变以菱铁矿为代表,形成于中性-弱碱性环境;成矿早期矿物蚀变以赤铁矿、针铁矿、黄铁矿、水云母和高岭石等为代表,形成于酸性环境;成矿晚期矿物蚀变以伊利石和铁白云石为代表,形成于弱碱-碱性环境;成矿期后矿物蚀变以方解石为代表,形成于碱-强碱性环境.因此,钱家店铀矿床经历了成岩期中性-弱碱性环境→成矿早期酸性环境→成矿晚期弱碱-碱性环境→成矿期后碱-强碱性环境的转变.      

A survey of pyritised animal,plant, and trace fossils and concretionary pyrites,Germav Formation,southeastern Turkey

The sulphide-bearing rocks of the Upper Cretaceous Germav Formation in southeastern Turkey (Bozova–Urfa) and the morphologically varied sulphide occurrences they contain have been investigated. Pyrite and marcasite are the main sulphide minerals; lesser bravoite and millerite also occur. Pyritised branches and leaves, trace fossils, and animal microfossils and macrofossils are abundant. Most of the concretionary and authigenic concretionary pyrite occurrences are probably related to burrows. The concretionary pyrites have low Co and high Ni contents and low Co:Ni ratios. The pyrite-rich lithostratigraphic sequences were deposited in a deep-sea environment, and pyrite mineralization developed in syn-sedimentary, early diagenetic and epigenetic stages under anoxic conditions. To cite this article: C. Bölücek, B. Ilhan, C. R. Geoscience 338 (2006).     

基于近红外岩心光谱扫描技术研究鄂尔多斯盆地彭阳铀矿床矿物分布特征

砂岩型铀矿作为一种以表生流体作用为主的后生矿床,发育较多低温矿物。甘肃省彭阳铀矿是近年来新发现的一处深部砂岩型铀矿床,具有砂体规模大、铀矿化面积广、厚度大、等特点。在含矿层及周边发育方解石、石膏、黄铁矿、黏土矿物等低温成因矿物,研究矿物的空间分布特征及其与铀矿物的关系,对判别成矿流体的主要来源、性质以及对铀成矿的控制作用具有重要意义。近红外岩心光谱扫描技术可无损、快速、批量地识别出岩心中的层状硅酸盐矿物(如高岭石、蒙脱石、绢云母等),硫酸盐矿物(如石膏、明矾石等),碳酸盐矿物(如方解石、白云石等)等矿物信息,本文基于该技术对彭阳铀矿床的矿物类型及其组合进行研究。结果表明：洛河组发育高岭石、蒙脱石、伊利石(伊/蒙混层)、绿泥石、碳酸盐、石膏、铁氧化物等矿物,铀矿段的矿物组合为“伊利石(伊/蒙混层)+石膏+碳酸盐”,局部可见高岭石。根据矿物组合特征反演流体作用,洛河组含铀矿段矿在沉积期主要是一套碱性环境,成矿期存在还原性酸性流体的注入。     

柴北缘冷湖砂岩型铀矿铀矿物赋存特征及成因机制

冷湖铀矿床是近年来在柴达木盆地北部新发现的具有工业价值的砂岩型铀矿床,为了研究该地区铀矿物的类型、成分特征、赋存形式及铀成矿作用,本文在野外地质调查的基础上,对下侏罗统小煤沟组相关蚀变矿物进行了矿相学、电子探针、背散射电子成像分析.研究发现,冷湖小煤沟组矿石主要包括杂砂岩型及碳质砂岩型两种,整体发育后生蚀变.铀矿物主要...     

柴北缘冷湖地区砂岩型铀矿床地质特征及成矿条件分析

冷湖地区砂岩型铀矿是近年柴北缘新发现的具有工业价值的铀矿床,为了进一步研究该地区砂岩型铀成矿岩石学及矿物学特征、铀成矿条件等问题,本文在野外地质调查的基础上,利用偏光显微镜结合电子探针分析手段,对该区内大煤沟组中含矿岩石进行了系统研究.结果表明:研究区中侏罗统大煤沟组含矿岩石类型主要为(粉)砂质泥岩、薄层煤及细粒石英杂...     

松辽盆地钱家店砂岩型铀矿床含矿岩系组成特征与铀成矿作用*

松辽盆地钱家店砂岩型铀矿床自勘查以来不断获得重大发现,已成为超大型铀矿床。该区矿床地质特征、成矿特点有过不少报道,但就其含矿建造的详细岩石学特征(蚀源区母岩)及有利的成矿条件等还需要随着研究程度的加深不断完善。铀矿的成矿作用包括导致铀元素集中形成铀矿的各种地质作用,其中,铀含量高且容易析出铀的源岩是铀成矿的物质基础,后期的氧化—还原、矿化蚀变是铀矿形成的关键。作者主要利用微观实验分析的方法,通过对钱家店砂岩型铀矿床赋矿岩石岩石学特征的详细分析,提出了矿层岩性主要为中—细粒长石岩屑砂岩、细粒长石岩屑砂岩和含泥砾砂岩和砂砾岩等,并且石英和长石总量与岩屑含量相近,岩屑主要以流纹岩、流纹质凝灰岩为主,次为粗面岩、正长细晶岩、花岗岩、花岗斑岩、安山岩、硅质岩和泥岩等。后生蚀变碳酸盐化、高岭石化较为普遍,局部强烈,其次黄铁矿化、氧化铁化,偶见重晶石化。常见深部油气渗入在赋矿层中出现油渍、油斑、溢散晕圈,共生黄铁矿莓球群及微细粒黄铁矿聚晶。铀的存在形式为铀矿物(沥青油矿、铀石)和吸附状态。分析了多成因—多阶段成矿模式,即沉积预富集阶段—层间渗入成矿阶段—油气改造富集成矿阶段—油气还原护矿阶段。     

Characteristics and uranium mineralization of ore-bearing rock series in Qianjiadian sandstone-type uranium deposits,Songliao Basin

The Qianjiadian sandstone-type uranium deposit in Songliao Basin has become an ultra-large uranium deposit since its exploration and continuous development. The geological and metallogenic characteristics of this area have been studied widely since its discovery,but the detailed petrological features of its ore-bearing construction and favorable metallogenic conditions still require much detailed research. The mineralization of urnium deposit includes various geological processes resulting in the accumulation of uranium element. The source rock with high uranium concentration and much easier for the leaching of uranium is the basis of uranium mineralization. The later oxidation-reduction,mineral alteration are the key for the uranium deposits. In this paper,the petrological characteristic of lithology sandstone-type uranium deposit is studied by using the micro experimental analysis. It is found that the host rocks are primarily composed of medium-fine grained feldspar lithic sandstone,fine grained feldspar lithic sandstone,boulder-clay-bearing sandstone and glutenin. The amount of quartz and feldspar are close to the rock debris. The debris are mainly composed of rhyolite,rhyolitic tuff,and some trochyte,ayenite-aplite,granite,granite porphyry,andesite,silicalite and mudstone etc. the epigenetic alteration includes the carbonatization and kaolinization is general and intense at the local region,followed by the secondary epigenetic alteration includes pyritization,ferrugination and little baratization. Deep oil and gas infiltrate into the oil-bearing strata causing the oil stains,spots and spillage. The symbiosis of pyrite berry globule and micritic pyrite are common. The uranium element exists in the uranium-bearing minerals(e.g.,asphalt and coffinite)as well as the adsorbed state. The multi-genesis and multi-stages of the metallogenic model is established,i.e.,sedimentary preconcentration stage-interlayer infiltration stage-the oil and gas transformation stage-the oil and gas reduction stage.     

Syngenetic origin for the sediment-hosted disseminated gold deposits in NW Sichuan,China: ore fabric evidence

Sediment-hosted disseminated gold deposits in NW Sichuan China have many features in common with the well-known Carlin-type deposits in the western United States. They are hosted by Middle–Upper Triassic turbidites composed of 1300–4300 m of rhythmically interbedded, slightly metamorphosed calcareous sandstone, siltstone, and slate. The ore bodies are typically layer- or lens-like in shape and generally extend parallel to the stratification of the host sedimentary rocks, with a strike length of tens to several hundreds of meters. The immediate host rocks consist mainly of calcareous slate and siltstone characterized by high contents of organic matter and diagenetic pyrite. The main primary ore minerals associated with gold mineralization include pyrite, arsenopyrite, realgar, and stibnite. Gangue minerals comprise mostly quartz, calcite and dolomite. Gold is extremely fine-grained, usually less than 1 μm, and cannot be seen with an electron microscope.Two types of ore mineralization have been recognized in the deposits. The stratiform ores are composed of rhythmical interbeds of sulfides (e.g., pyrite, arsenopyrite, realgar, stibnite) interpreted to be authigenic and detrital quartz, quartzite, sericite, and graphite of allogenic origin. They were folded and deformed concordantly with host rocks, and grade both vertically and laterally into normal country rocks. Another type of ore forms a network of numerous gold-bearing veins and veinlets of quartz–calcite–sulfides of millimeter-, centimeter-, decimeter-, and even meter-scale in width. The network ore randomly fills fissures, microfissures, and cleavages, but still is stratabound in character. Detailed studies on ore fabrics show abundant evidence for synsedimentary origins, although subsequent diagenesis, metamorphism, tectonic deformation, and epigenetic hydrothermal activity have significantly remolded the primary fabrics. Primary fabrics are shown either by rhythmical interbeds of different mineral components parallel to the bedding, or by the change of grain size of the same minerals such as pyrite, realgar, and stibnite. The layer inhomogeneity of the stratiform ore is clarified by parallel overprints of later schistosity planes, resulting in distinct grain orientation and elongation, aggregate polarization, and undulating extinction of ore minerals, especially of mechanically and chemically extremely mobile ones, such as realgar and stibnite.It is proposed that the stratiform ores in these Chinese deposits were most probably formed concurrently with their host Middle–Upper Triassic turbidites in submarine, hot spring environments, while the network mineralization was formed as a result of complicated processes such as diagenesis, weak metamorphism, tectonic deformation, and epigenetic hydrothermal activity, responsible for the remobilization or reworking of the pre-existing stratiform ores. Geochemical data also support this genetic model.     

新疆萨瓦莆齐铀矿床沥青还原沥青铀矿的直接证据

许多含油气盆地均有铀矿床分布,油气在铀矿化中的作用及其与铀矿化的关系是广大铀矿工作者关注的问题。通过对新疆萨瓦莆齐铀矿床中铀矿石的偏光、荧光反射显微镜研究和电子探针分析测试,首次在矿石中发现沥青-沥青铀矿-黄铁矿脉,对脉体中沥青、沥青铀矿、黄铁矿的空间关系研究表明,沥青铀矿和黄铁矿均受沥青脉的控制,是脉体中还原能力较强的轻烃类物质与周围环境相互作用的产物,矿物中的铀和铁元素主要来自周围环境而非脉体本身。矿床可能存在多期油气活动,沥青铀矿可能主要形成于早期油气活动,晚期油气衍生的沥青质沿早期生成的沥青铀矿微裂隙充填改造。