鄂尔多斯盆地北东部纳岭沟铀矿床红色蚀变矿石成因及其地质意义

鄂尔多斯盆地北东部纳岭沟铀矿床是近年来发现的大型砂岩型铀矿床。与国内外典型层间氧化带型铀矿床明显不同,纳岭沟铀矿床不仅矿体呈板状、似层状产出,受单层灰绿色古氧化砂体与下伏灰色砂体的交界面控制,且远离顶底板,部分含矿岩石在宏观上表现为红色含炭屑矿石,微观上出现铀石-赤铁矿(针铁矿)-黄铁矿等特殊矿物共生组合。在综合岩矿鉴定、电子探针分析、酸解烃分析等成果认识的基础上,结合前人流体障铀成矿理论的实验和数学模拟结果认为,纳岭沟铀矿床是含氧含铀水与深部还原性流体相互作用的产物,且矿体形成过程中含氧含铀水和深部还原性流体的界面变化是红色蚀变矿石形成的关键原因,而持续强的含氧含铀水和较弱的深部还原性流体作用是形成板状矿体的主要因素。     

松辽盆地钱家店铀矿床层间氧化带结构定量表征及制约因素

层间氧化带精细结构的量化表征对揭示砂岩型铀成矿规律至关重要.利用系列沉积学和地球化学编图对松辽盆地钱家店铀矿床层间氧化带结构进行了量化表征,发现该矿床层间氧化带主要由红色砂岩、浅黄色砂岩、灰白色砂岩、灰色含矿砂岩和原生灰色砂岩构成,分别对应于强氧化亚带、弱氧化亚带、微弱氧化亚带、过渡带和还原带.铀矿化与层间氧化带内部结构关系密切:工业铀矿体主要发育在过渡带,微弱氧化亚带矿体连续性相对较差,弱氧化亚带发育零星铀矿化,还原带靠近过渡带一侧发育低品位的零星铀矿化.铀储层内部结构和沉积相对层间氧化带发育具有重要制约作用:辫状河砂体及辫状分流河道砂体是氧化带发育区域;辫状分流河道边部及分流间湾中决口扇砂体是过渡带发育区域.      

Supergene processes and uranium ore formation in the Ronneburg ore field,Germany

The Ordovician-Lower Carboniferous sequence of slightly metamorphosed gray carbonate-terrigenous rocks contains the Silurian black cherty shales enriched in carbon (6–9%), pyrite (6–7%), and uranium (∼30 ppm). The uranium ore is localized at the pinch-out of areal and linear zones of the Early Permian supergene (exogenic) oxidation of rocks expressed in reddening (hematitization). U, As, Sb, Cu, Ni, Mo, and Ag have been removed from the oxidized black shales and concentrated in the cementation zone in form of pitchblende and sulfides in wall-rock disseminations and veinlets largely hosted in carbonate-bearing rocks. In the Late Permian, during deposition of the upper Rotliegende and Zechstein, the fractures in the basement were filled with carbonates and sulfates; uranium was partly redeposited along with enrichment in Pb and Zn. Mesozoic and Cenozoic supergene processes altered uranium ore insignificantly.     

广东大亚湾西北部新发现铀矿点及找矿远景讨论

2003年在广东大亚湾西北部新发现了一处火山岩型铀矿点,经刻槽取样分析,铀矿石品位高达0.459%。该处铀矿物成份主要是沥青铀矿和次生铀矿物,前者 UO_2最高为94%,Al_2O_3<1%,P_2O_5含量变化大,按照 P_2O_5含量可分两组,其一变化于2.23%～2.57%,另一组变化于17.96%～19.95%;次生铀矿物含 UO_3大约为60%左右,Al_2O_3在1.6%～3.0%之间,P_2O_5变化于10%～15%。对含矿岩石及围岩进行了岩石学和地球化学研究,结果表明,出露的岩石主要为流纹质岩石,与著名的相山矿田的岩石类型相似。岩石具有高的 LREE/HREE 值,Eu 负异常并不普遍。从主、微量元素及稀土元素特征来看,含矿岩石及围岩差别不大,总特征与一般的钙碱性火山岩相似。新发现的铀矿化带范围虽然不大,但含矿岩石铀品位高,所处构造环境与相山铀矿田的某些矿床有一定的相似性,是值得注意和进一步工作的地区。     

相山铀矿田成矿流体特征:来自微量、稀土元素地球化学证据

相山铀矿田的成矿流体性质和来源存在争议,为进一步探讨相山铀矿田成矿流体的性质和来源,本文对相山铀矿田西部的居隆庵铀矿床和北部的沙洲铀矿床中的新鲜围岩、蚀变围岩及矿石的微量、稀土元素含量及其变化进行了研究。结果显示:在含较多热液成因萤石的居隆庵铀矿床中,从新鲜围岩到蚀变围岩到矿石,Zr、Hf含量先降低再升高;而在含少量热液萤石的沙洲铀矿床中,新鲜围岩、蚀变围岩和矿石的Zr、Hf含量基本一致。鉴于富F流体易汲取岩石中的Zr、Hf,因此,这两个矿床中不同类型样品Zr、Hf含量的不同变化趋势,可能与居隆庵铀矿床的成矿流体富F、而沙洲铀矿床的成矿流体相对贫F有关。这两个铀矿床中矿石的稀土配分曲线与其各自的新鲜及蚀变围岩的稀土配分曲线形态相似但又存在差异,说明每个矿床的新鲜围岩、蚀变围岩和矿石之间的稀土元素既具有继承性、又受到不同性质的流体的影响。居隆庵铀矿床中矿石显示Eu负异常,可能主要是继承了围岩的Eu负异常;沙洲铀矿床中矿石Eu显示弱负异常至弱正异常的特征,可能与围岩中斜长石因热液蚀变作用而释放出的Eu的进入流体有关。基于新鲜围岩、蚀变围岩及矿石的U和REE研究,推断居隆庵铀矿床成矿流体中U和REE均以F的络合物形式迁移;但沙洲铀矿床中铀矿石品位较低,可能是与流体中相对贫F有关。     

萨瓦甫齐铀矿床层间氧化带地球化学特征

萨瓦甫齐铀矿床不同地段层间氧化带的氧化还原程度是不同的。利用诸如w（Fe3＋）/w（Fe2＋）、w（Ra）/w（U）和有机炭等地球化学参数探讨了萨瓦甫齐铀矿床层间氧化带的地球化学特征,即矿床西南部层间氧化带氧化程度较弱,表现为全硫（∑S）、总铁（TFe）和矿石的铀质量分数低;而矿床中部及东北部层间氧化带氧化程度较强,尤其以东北部突出,它们的全硫、总铁和矿石的铀质量分数均高。铀矿化强弱明显与层间氧化带的氧化还原程度有关,层间氧化带的氧化程度越强,铀矿化则愈强;反之,则弱。     

Behavior of uranium under conditions of interaction of rocks and ores with subsurface water

The behavior of uranium during interaction of subsurface water with crystalline rocks and uranium ores is considered in connection with the problem of safe underground insulation of spent nuclear fuel (SNF). Since subsurface water interacts with crystalline rocks formed at a high temperature, the mineral composition of these rocks and uranium species therein are thermodynamically unstable. Therefore, reactions directed toward the establishment of equilibrium proceed in the water-rock system. At great depths that are characterized by hindered water exchange, where subsurface water acquires near-neutral and reducing properties, the interaction is extremely sluggish and is expressed in the formation of micro- and nanoparticles of secondary minerals. Under such conditions, the slow diffusion redistribution of uranium with enrichment in absorbed forms relative to all other uranium species is realized as well. The products of secondary alteration of Fe- and Ti-bearing minerals serve as the main sorbents of uranium. The rate of alteration of minerals and conversion of uranium species into absorbed forms is slow, and the results of these processes are insignificant, so that the rocks and uranium species therein may be regarded as unaltered. Under reducing conditions, subsurface water is always saturated with uranium. Whether water interacts with rock or uranium ore, the equilibrium uranium concentration in water is only ≤10^?8 mol/l. Uraninite ore under such conditions always remains stable irrespective of its age. The stability conditions of uranium ore are quite suitable for safe insulation of SNF, which consists of 95% uraninite (UO₂) and is a confinement matrix for all other radionuclides. The disposal of SNF in massifs of crystalline rocks at depths below 500 m, where reducing conditions are predominant, is a reliable guarantee of high SNF stability. Under oxidizing conditions of the upper hydrodynamic zone, the rate of interaction of rocks with subsurface water increases by orders of magnitude and subsurface water is commonly undersaturated with uranium. Uranium absorbed by secondary minerals, particularly by iron hydroxides and leucoxene, is its single stable species under oxidizing conditions. The impact of oxygen-bearing water leads to destruction of uranium ore. This process is realized simultaneously at different hypsometric levels even if the permeability of the medium is variable in both the lateral and vertical directions. As a result, intervals containing uranyl minerals and relics of primary uranium ore are combined in ore-bearing zones with intervals of completely dissolved uranium minerals. A wide halo of elevated uranium contents caused by sorption is always retained at the location of uranium ore entirely destroyed by weathering. Uranium ore commonly finds itself in the aeration zone due to technogenic subsidence of the groundwater table caused by open-pit mining or pumping out of water from underground mines. The capillary and film waters that interact with rocks and ores in this zone are supplemented by free water filtering along fractures when rain falls or snow is thawing. The interaction of uranium ore with capillary water results in oxidation of uraninite, accompanied by loosening of the mineral surface, formation of microfractures, and an increase in solubility with enrichment of capillary water in uranium up to 10^?4 mol/l. Secondary U(VI) minerals, first of all, uranyl hydroxides and silicates, replace uraninite, and uranium undergoes local diffusion redistribution with its sorption by secondary minerals of host rocks. The influx of free water facilitates the complete dissolution of primary and secondary uranium minerals, the removal of uranium at the sites of groundwater discharge, and its redeposition under reducing conditions at a greater depth. It is evident that the conditions of the upper hydrodynamic zone and the aeration zone are unfit for long-term insulation of SNF and high-level wastes because, after the failure of containers, the leakage of radionuclides into the environment becomes inevitable.     

对松辽盆地钱家店凹陷铀成矿作用的重新认识

钱家店凹陷中的含矿层位主要为上白垩统姚家组,前人认为其中的红色砂岩为原生成因,但大量的证据证实砂岩原生应以灰色为主,红色砂岩为后生氧化蚀变造成,并控制着钱家店铀矿床铀矿化的产出。在此基础上建立该矿床的后生蚀变分带,依次为红色蚀变带、黄色蚀变带、灰白色蚀变带、过渡带、原生带,红色蚀变带为主要的氧化带,铀矿化主要集中在过渡带。平面上铀矿化主要分布于层间氧化带前锋线附近的位置,并在氧化舌状体的前端和两个氧化舌状体之间存在铀的富集。文章最后还建立了该矿床的成矿模式,并对区域上层间氧化带的展布进行了讨论。     

北秦岭丹凤地区产铀花岗岩稀土元素地球化学特征

针对北秦岭丹凤地区产铀花岗岩的区域地层、赋矿围岩、蚀变岩和铀矿石进行稀土元素地球化学研究,结果表明:各类样品具有大体类似的LREE富集及Eu负异常的稀土配分模式,表明它们之间稀土元素特征具有继承性;赋矿黑云母二长花岗岩与区域地层(丹凤岩群变质基性火山岩)稀土元素特征指示,二者均形成于岛弧环境;蚀变花岗岩和铀矿石主要继承了赋矿花岗岩的特征。各类样品Y/Ho值变化范围狭窄,为25.09~33.46,显示它们具有共同的源区。铀矿石具有最高的w_B(∑HREE),且与铀矿石的品位存在正相关关系,暗示HREE与铀的迁移具有同步性。     

伊犁盆地层间氧化带砂岩型铀矿成矿模式

本文通过对５１２、５１１矿床及其它矿点的铀源、地质构造、含矿主岩岩性、古气候、层间氧化带发育条件、成矿水文地质条件等方面的研究，提出了伊犁盆地层间氧化带砂岩型铀矿的成矿模式。     

十红滩地浸砂岩铀矿层间氧化带蚀变矿物群

十红滩砂岩型铀矿床是我国大型层间氧化带型砂岩铀矿床之一。层间氧化带型砂岩铀矿含矿砂层在含氧含铀水的渗入径流过程中,由于水介质性状的变化,在与砂体发生水岩作用时形成了完全氧化带、不完全氧化带、还原带和原生带等不同地球化学亚带及其相对应的蚀变矿物群,即完全氧化带为褐铁矿(针铁矿、水针铁矿)、伊利石、蒙脱石、少量黄钾铁矾的蚀变矿物群;不完全氧化带为褐铁矿(针铁矿、水针铁矿)、黄钾铁矾、蒙脱石、伊利石、少量绿泥石、高岭石的蚀变矿物群;还原带为沥青铀矿、黄铁矿、高岭石、绿泥石、少量蒙脱石、伊蒙混层粘土、伊利石和碳酸盐等新生蚀变矿物群;原生带的新生蚀变矿物群以黄铁矿、绿泥石、高岭石为主,有时出现少量碳酸盐、蒙脱石和伊利石等。     

Elemental Geochemistry of the Interlayer Oxidation Zonein the Shihongtan Sandstone Type Uranium Deposit, Xinjiang

1 Geological Setting making the southern margin of Turpan-Hami basin one of the important uranium-productive regions of interlayer The Turpan-Hami basin is one of the three greatest basins oxidation type sandstone-hosted uranium deposits inin the Xinjiang Uygur Autonomous Region. It is located in China. Up to now, the large-scale Shihongtan uraniumthe Junggar-Turpan microplate at the southeastern end of deposit and some uranium ore occurrences have beenthe Kazakhstan-Junggar plate. The b…     

吐哈盆地十红滩铀矿床地质特征及控矿因素分析

叙述了吐哈盆地地质概况；十红滩铀矿区找矿目的层地质和砂体特征；重点对层间氧化带的纵横展布规律、地球化学分带性及前锋与铀矿化的关系作了阐述；对十红滩铀矿床南、北矿带的空间分布、形态、规模、物质成分、铀存在形式及南、北矿带差异做了研究。通过分析，最后得出十红滩铀矿床控矿因素是层间氧化带、鼻状隆起（南矿带）和北西向断裂构造（北矿带）、同时说明了局部铀矿化产出的决定因素。     

商丹三角地区花岗伟晶岩型铀矿成矿环境研究及远景评价

花岗伟晶岩型铀矿是目前发现的一种新类型铀矿。这种矿床的晶质铀矿是从花岗岩浆分异出来的富铀岩浆中结晶而成的。下元古界秦岭群是成矿有利环境,韧性剪切带是控岩控矿的主要构造。这种类型铀矿在商丹三角地区的远景是可观的。     

地幔流体与铀成矿作用

文中探讨了地幔流体铀成矿作用的可能性 ,并以相山世界级铀矿田为例 ,阐明了地幔流体铀成矿作用的主要特征。岩石圈之下存在一个富含放射性生热元素的富集圈 ,在造山带崩塌阶段 (岩石圈拆沉或减薄 )以及弧后拉张环境下 ,富集圈中的U、Th将随地幔流体一起上升迁移至地壳中直接成矿。相山铀矿床就是在弧后拉张环境下由当地富集地幔流体上升迁移至早先火山杂岩裂隙带中沉淀成矿而形成的。弧后拉张环境有利于地幔流体上升 ,早先的火山通道和火山杂岩中非常发育的裂隙为成矿流体提供了迁移和赋矿空间 ,成矿与幔源岩浆活动 (煌斑岩 )相伴随 ,成矿流体和成矿物质具有幔源特征 ,地幔中放射性生热元素富集圈为其提供了强大的物质基础 ,从而形成了相山超大型铀矿田。     

松辽盆地钱家店铀矿床层间氧化与铀成矿作用

通过系统的岩心观察、剖面对比和分析,笔者认为松辽盆地钱家店铀矿床的控矿层间氧化带主要由红色氧化砂岩与局部分布的黄色砂岩和灰白色砂岩组成。红色砂岩中含炭屑、黄铁矿、钛铁矿、菱铁矿,并遭强烈氧化,推断其原生色应主要为灰色,由后生氧化作用将其改造而呈现红色。层间氧化带的形态和展布特征主要受沉积相控制,后者也同时控制着铀矿化的产出。铀矿化在剖面上主要定位于红色氧化带减薄或尖灭部位,平面上主要分布于红色氧化带前锋线附近。     

伊犁盆地库捷尔太铀矿床层间氧化带与铀矿化特征研究

库捷尔太铀矿床(又名512铀矿床)是中国第一个典型的层间氧化带可地浸砂岩型铀矿床.矿床形态、规模、品位和分布都受控于层间氧化带.而层间氧化带在空间上具有多层性、叠加性和分带性.本文通过对库捷尔太铀矿床层间氧化带展布、分带性、岩石特征和矿体分布,铀矿物和价态铀的分布组合特点的分析,来进一步认识层间氧化带可地浸砂岩型铀矿床成矿规律,丰富水成铀矿床理论,以便对今后在寻找这类矿床时具有一定的指导意义.     

松辽盆地南部砂岩型铀矿储层结构与铀成矿作用

以松辽盆地南部DL地区砂岩型铀矿为目标,在沉积学背景研究的基础上,开展铀储层结构与铀成矿作用研究。通过钻孔数据统计及系统的取样分析并编制铀储层非均质性图件,精细地刻画了姚家组铀储层的几何形态和复杂结构,充分展示了铀储层的定量非均质性。结果显示,区内灰色砂体多为原生灰色砂体,而下氧化带在沉积期后经历了较强的表生流体改造,为后生氧化带,矿体主要分布于河道砂体分岔处,以及从无隔挡层到隔挡层突然变厚的河道砂体边缘而非河道中央,其形态受氧化还原界面控制以板状为主。综合分析认为,表生流体成矿作用经历了晚白垩世姚家组含矿主岩预富集与表生流体叠加改造成矿2个阶段。通过对比DL地区储层结构对铀成矿的控制作用,在BL地区优选出3片找矿靶区,为下一步的勘查工作提供理论依据。     

铅硐山铅锌矿床的氧化富集规律

铅硐山铅锌矿床氧化带较发育,提出用氧化率来标定矿石的氧化作用特征。从矿区的气候、地形、构造、矿体产状、矿物组成和矿化主岩等对氧化富集作用的影响,总结了铅硐山矿床矿石氧化富集规律。并运用矿石氧化富集规律指导氧化矿开采,取得了较好的经济效益。     

The outlook for the discovery of new types of economic uranium deposits in the Kodar-Udokan zone of the Transbaikal territory in Russia

On the basis of detailed fieldwork and analytical procedures (microprobe, X-ray diffraction, chemical analysis, etc.), ores and altered wall-rock rocks of the Khadatkanda and Etyrko deposits in the Kodar-Udokan mineragenic zone were studied. Economic concentrations of gold and some other accompanying metals have been established in ore of the Khadatkanda uranium deposit in the Syul’ban uranium district. REE-U lodes with brannerite-uraninite have been found at the Etyrko Fe-Ti-V deposit related to the Chinei layered pluton in the Udokan mining district. The outlook for the discovery of new types of economic uranium deposits is substantiated with respect to the known hydrothermal uranium ore objects and nontraditional setting related to the layered mafic-ultramafic intrusions.