确定层间氧化带型砂岩铀矿床后生分带的水文地球化学研究方法

本文从水文地球化学角度,归纳了确定层间氧化砂岩铀矿床后生分带的水文地球化学标志,在此基础上,系统论述了确定层间氧化带型砂岩铀矿床后生分带的水文地球化学研究方法：水文地球化学标志选择,水文地球化学取样,水文地球化学样品分析测试和后生分带的确定。     

我国砂岩型铀矿分带特征研究现状及存在问题

作为一种重要的国家战略资源,砂岩型铀矿床是当今世界上最重要的铀矿床类型之一。本文详细地介绍了砂岩型铀矿在国内外的分布特征及占比情况,并对外生地质作用矿床类型中表生流体作用形成的层间渗透砂岩型和潜水渗透砂岩型铀矿床进行了讨论,发现层间渗透砂岩型铀矿床在外表颜色、矿物组合以及地球化学等方面均具有明显的氧化-还原分带现象,此外,矿床内部还具有细菌分带现象。颜色分带在氧化带、氧化-还原过渡带以及还原带之间具有明显不同的特征;矿物组合在不同分带之间各不相同;地球化学分带表现为U、TOC含量以及Fe~(2+)/Fe~(3+)、Th/U比值在各分带之间差异较大。此外,硫酸盐还原菌、硫杆菌、铁细菌及硝化菌等细菌在不同分带之间的数量相差悬殊,而且硫酸盐还原菌数量与TOC呈明显正相关性。通过矿化带内的碳、硫同位素分析,发现硫酸盐还原菌参与了成矿过程,推测其可能是导致碳、硫同位素分馏的主要因素。总体来看,颜色分带、矿物分带、地球化学分带以及细菌分带均与氧化-还原分带呈耦合关系。本文通过总结层间渗透砂岩型和潜水渗透砂岩型铀矿床的成矿模式和当前分带研究中存在的问题,提出了由细菌、地球化学反应参与的砂岩型铀矿床成矿机理,以及未来亟需解决的若干关键科学问题。典型砂岩型铀矿床的分带现象在物、化、探、遥等领域的异常响应对寻找砂岩型铀矿床具有重要的指导意义。     

地下水排泄区——水成铀矿床形成中的聚矿构造

地下水在成矿过程中的特殊作用与携带一系列成矿物质的大量层状水、裂隙水和潜水的高容矿性和活动性有关。形成水成铀矿床的外生后成过程,也是地下水地质作用的结果。已有文献详细讨论过反映铀矿石后生成矿实质的放射性水文地球化学分带性。形成层状氧化带的含氧水中的铀,停留在氧化还原界面上,并形成铀的矿化带。矿化带向下顺着水流方向渐     

吐哈盆地水文地球化学分带与铀矿化关系浅析

确立了吐哈盆地水中铀的存在形式，分析了铀在水中的迁移规律和沉淀条件。并运用层间氧化带的成矿机理，阐述了各地球化学分带的水文地球化学特征，引用“饱和指数”把铀在水中的饱和程度给予量化，从而确定了盆地水中铀的沉淀区间。利用γNa＋／γCl─和γCa＋＋／γCl─划分出水文地球化学分带及综合岩石地球化学分带，为寻找层间氧化带型铀矿提供了水文地球化学依据。指出艾丁湖自流水斜地为形成层间氧化带型铀矿的有利地段。     

污染物质影响地下水化学成分变化的地球化学和生态学后果

被污染地下水的地球化学分类表明，污染物质进入地下水后，导致其中形成一套严格限定的，可用Eh-pH指标表达的地球化学条件，并导致出现新的、前所未知的水文地球化学现象。后者表现为：新的地球化学类型水的形成，酸性和碱性水分布面积的增大，水的氧化－还原电位的降低和逆向分带，以及水化学元素迁移形式的改变。从水中已发现的一系列污染物质（首先是氮的化合物和有机物）看，水文地球化学体系已变为始终不平衡的体系，这就决定了水文地球化学体系的不确定性和未来水文地球化学现象的不可预知性。     

赛汉高毕-巴彦乌拉地区铀矿化远景区预测探讨

在研究赛汉高毕-巴彦乌拉地区区域地质背景及水文地质特征的基础上.对该地区铀成矿水文地球化学特征进行了探讨.结果表明,该地区具有相对独立、完整的地下水补给、径流、排泄系统,从盆地边缘到盆地中心具有明显从氧化环境到还原环境的水文地球化学分带特征,水中铀经历了由溶滤迁移到还原沉淀的矿化过程.在二连盐池、赛汉高毕-塔木敌地区和巴彦乌拉-白音塔拉地区有十分有利的铀成矿条件和良好的铀成矿远景.     

潮水盆地铀成矿水文地球化学研究

在分析潮水盆地自然地理、地质背景及水文地质特征的基础上，对盆地铀成矿水文地球化学特征进行了探讨。结果表明：潮水盆地为-渗入型自流水盆地，其深层地下水中铀存在形式为UO2(CO3)n^2-2n。；从盆地边缘到盆地中心具有明显从氧化环境到还原环境的水文地球化学分带特征，水中铀经历了由溶滤迁移到还原沉淀的矿化过程；在盆地北缘的照壁山-白芨芨、阿右旗-陶家井地区，西南部的平易-平山湖地区具备十分有利的铀成矿条件和良好的铀成矿远景。     

层间氧化带砂岩型铀矿床微生物地球化学特征及与铀成矿的关系研究——以吐鲁番-哈密盆地十红滩铀矿床为例

通过样品采集、细菌培养和鉴定等，首次在中国大型的十红滩层间氧化带砂岩型铀矿床容矿层中发现不同种群的细菌。氧化带主要分布铁细菌、硫杆菌、硝化菌等好氧菌，矿石带主要分布厌氧的硫酸盐还原菌，其种类和数量上具明显的生物地球化学分带性，并与岩石的地球化学分带性一致。首次利用容矿层的硫酸盐还原菌在室内进行了硫酸盐还原试验。根据细菌的代谢特征，结合硫酸盐还原菌还原试验，分析了细菌在层间氧化带形成、铀氧化迁移和还原成矿过程中的作用。     

岩溶关键带水文地球化学研究进展

岩溶关键带处于岩石、水、土壤、大气、生物五圈交汇地带。正确认识岩溶关键带的结构、特点及其水文地球化学过程是当前地球关键带与岩溶水科学研究的重点问题。本文基于对国内外相关研究成果的归纳整理,剖析了岩溶关键带水文地球化学内涵、岩溶关键带水动力垂向分带、岩溶关键带框架下的水文地球化学过程与机制, 探寻变化环境下岩溶关键带水文地球化学过程演变的规律与驱动机制。指出了当前研究中存在的薄弱环节:目前工作仅停留在传统岩溶地下水科学工作范畴,未从岩溶关键带框架体系的角度考虑植物冠层至岩溶含水层之间水文地球化学过程及其耦合关系,未考虑新污染物持续输入、地球大数据科学工程深入实施、全球碳排放路径逐渐改变等时代因素对岩溶水文地球化学研究的潜在影响。进一步的研究可以从以下方面开展:基于岩溶关键带框架体系的新污染物水文地球化学研究,基于大数据框架体系的岩溶水文地球化学研究,“双碳战略”下的岩溶水文地球化学研究,岩溶关键带水文地球化学驱动的物质转化与能量迁移过程及其耦合以及高分辨率监测、评估与模拟手段的综合应用。     

准噶尔盆地东部将军庙地区砂岩型铀矿层间氧化带地球化学特征初步研究

通过对目的层层间氧化分带岩石学、地球化学指标、常量元素及其变化规律的分析,初步研究了准噶尔盆地东部将军庙地区砂岩型铀矿的地质地球化学特征。研究认为:(1)将军庙地区的层间氧化带可分为强氧化亚带、弱氧化亚带、过渡带和原生还原带;(2)研究区氧化作用存在长时期间断,造成过渡带铀富集较弱,矿带范围较局限;(3)SiO_2、MgO和TiO_2与铀元素的富集具一定相关性。     

Compositional zonation in garnets in peridotite xenoliths

Garnets in 42 peridotite xenoliths, most from southern Africa, have been analyzed by electron probe to seek correlations between compositional zonation and rock history. Xenoliths have been placed into the following 6 groups, based primarily upon zonation in garnet: I (12 rocks)-zonation dominated by enrichment of Ti and other incompatible elements in garnet rims; II (10 rocks)-garnet nearly homogeneous; III (8 rocks)-rims depleted in Cr, with little or no related zonation of Ti; IV (3 rocks)-slight Ti zonation sympathetic to that of Cr; V (3 rocks)-garnet rims depleted or enriched in Cr, and chromite included in garnet; VI (6 rocks)-garnets with other characteristics. Element partitioning between olivine, pyroxene, and garnet rims generally is consistent with the assumption of equilibrium before eruption. Although one analyzed rock contains olivine and pyroxene that may have non-equilibrated oxygen isotopes, no corresponding departures from chemical equilibrium were noted. Causes of zoning include melt infiltration and changes in temperature and pressure. Zonation was caused or heavily influenced by melt infiltration in garnets of Group I. In Groups III, IV, and V, most compositional gradients in garnets are attributed to changes in temperature, pressure, or both, and gradients of Cr are characteristic. There are no simple relationships among wt% Cr₂O₃ in garnet, calculated temperature, and the presence of compositional gradients. Rather, garnets nearly homogeneous in Cr are present in rocks with calculated equilibration temperatures that span the range 800–1500 °C. Although the most prominent Cr gradients are found in relatively Cr-rich garnets of rocks for which calculated temperatures are below 1050 °C, gradients are well-defined in a Group IV rock with T1300 °C. The variety of Cr gradients in garnets erupted from a range of temperatures indicates that the zonations record diverse histories. Petrologic histories have been investigated by simulated cooling of model rock compositions in the system CaO–MgO–Al₂O₃–SiO₂–Cr₂O₃. Proportions and compositions of pyroxene and garnet were calculated as functions of P and T. The most common pattern of zonation in Groups III and IV, a decrease of less than 1 wt% Cr₂O₃ core-to-rim, can be simulated by cooling of less than 200 °C or pressure decreases of less than 1 GPa. The preservation of growth zonation in garnets with calculated temperatures near 1300 °C implies that these garnets grew within a geologically short time before eruption, probably in response to fast cooling after crystallization of a small intrusion nearby. Progress in interpreting garnet zonations in part will depend upon determinations of diffusion rates for Cr. Zonation formed by diffusion within garnet cannot always be distinguished from that formed by growth, but Ca–Cr correlations unlike those typical of peridotite suite garnets may document diffusion.     

冀西北姚家庄超镁铁岩-正长岩杂岩体中辉石的环带特征及意义

冀西北姚家庄存在一套晚三叠世的超镁铁岩-正长岩杂岩体,岩体内发育具有环带特征的单斜辉石。辉石的环带有两种:简单环带和复杂环带。简单环带一般为正环带,辉石核部的MgO和Cr2O3含量高,Si O2、Fe O和Na2O含量低;边部的主要氧化物含量与核部刚好相反。简单正环带可以分为两类,其中核边接触带平滑、由核到边化学成分具有渐变特征的正环带辉石可能是岩浆在分离结晶或地壳混染过程中形成。而核边接触带有熔蚀结构、由核到边化学成分突变的正环带辉石可能是早期结晶的辉石颗粒受到晚期低镁岩浆的溶蚀改造而成的。复杂环带具有核-幔-边结构,其中,核部低镁高铁、幔部高镁低铁、边部与核部相似,但其Mg#更低,这些特征暗示了岩浆混合作用的存在,形成辉石核部的母岩浆可能来自富集的岩石圈地幔,幔部高Mg#的特征指示了软流圈地幔物质的贡献,其边部低Mg#的特征则指示了地壳物质的加入。具有韵律环带的复杂辉石是在岩浆多期侵入的过程中形成的。辉石环带的组成特征表明,姚家庄杂岩体是由岩浆多期侵位形成的,后期侵入的岩浆与前期就位的岩浆不断反应,形成了具有多种不同环带特征的辉石,并最终形成了空间上由外到内依次为辉石岩、辉石正长岩和正长岩的环状杂岩体。结合前人的研究成果,推测形成姚家庄岩体的岩浆主要来源于富集的岩石圈地幔,并由少量地壳组分和软流圈物质的贡献。     

深圳沿海表层海水与地表水关系的地球化学分析

依据深圳沿海所取31件表层海水样品的水化学数据,对主要离子Ca2+、Mg2+、Na+、K+、SO42-和HCO3-与C l-以及B r-与C l-的关系作散点图分析。西海岸表层海水Ca2+、K+、SO42-和HCO3-与C l-的比偏离海水稀释线,源于其位于珠江河道影响范围,与珠江水有不同程度的混合;东海岸表层海水Ca2+、K+和HCO3-与C l-的比主要围绕海水稀释线波动,表明沿海表层海水流动缓慢,受表层海水蒸发和当地沿岸污染河水排泄的长期累积影响;靠近深圳湾的5件西海岸海水样品成分与东海岸表层海水相似。     

Multivariate statistical analysis and 3D-coupled Markov chain modeling approach for the prediction of subsurface heterogeneity of contaminated soil management in abandoned Guryong Mine Tailings, Korea

Various geological materials on the ground surface can be natural or artificial sources of pollutions. The spatial distribution of tailings is required to investigate the geological material pollutions. The objectives of this study were to determine the main factors influencing tailing zonations using a factor analysis, to determine the zonation of tailings with a cluster analysis, and to simulate zonations with three-dimensional coupled Markov chain (3D-CMC) modeling. The database was composed of 12 excavated exploratory holes in the Guryong mine tailings, for which there were analytical data covering the physical, chemical, and mineralogical aspects. The principal component analysis indicated that the tailing composition was mainly affected by three factors out of 21 variables: pH, cation exchange capacity, and mineral composition. Based on these main factors, the tailings were classified into five groups using a cluster analysis. Group I was approximately 50 cm deep from surface and had secondary gypsum (CaSO₄·2H₂O) and jarosite (KFe₃(SO₄)₂(OH)₆). Group II had low pH values caused by strong pyrite oxidation and the greatest amounts of the secondary minerals. In group III and IV, the quantity of the secondary minerals decreased. Group V was characterized by primary calcite (CaCO₃) composition. These results were applied to the CMC modeling, and the quantitative 3D distribution of tailing was verified. For the cost-saving prediction of subsurface heterogeneity, 3D-CMC modeling was executed using the selected eight holes data among twelve holes. The unknown four holes, GS3, GS6, GS8 and GS11, are identified as 89.7, 88.6, 80.7 and 81.1 %, respectively. They are recognized as 85.0 % of the total zonation. The zonation method of tailings executed in this study can be utilized in predicting the 3D distribution of the pollution factor. This may be a useful and economical method to identify the environmentally hazardous materials in underground systems.     

基于GIS技术的玉林-铁山港公路沿线崩塌、滑坡灾害危险性区划

文章以MAPGIS6.7、MORPAS3.0和Geodas 4.0软件为平台,综合应用信息量法、证据权法和模糊证据权法,采用两级混合的预测方法对玉林—铁山港公路沿线崩塌、滑坡地质灾害进行了危险性区划,共划分为高度危险性区、中高度危险性区、中度危险性区和轻度危险性区4级。预测结果显示:研究区崩塌、滑坡灾害危险性级主要为轻度危险等级。中高度—高度危险区范围较小,且主要分布于研究区中北部AK51、AK60~AK65和AK95~AK105路段;上述区段水系发育,沟谷较多,山坡陡峻,岩土体结构多具中厚层状坚硬、较坚硬砂岩、粉砂岩、砂砾岩夹软质泥岩、页岩岩组特征,断裂构造发育,地表残坡积层厚度大,结构松散,夏季暴雨频发,崩塌、滑坡灾害条件基本具备,易于形成和诱发;因此,应重点加强上述区段的灾害监测和防治工作。     

Microbiota and stratigraphy of lower Paleogene deposits of the Urma Plateau,Central Dagestan

The study of nannofossils, dinocysts, and foraminifera from Paleogene deposits of the Urma Plateau of Central Dagestan revealed the Paleocene-Eocene age of the Gray Formation, to apply zonations based on of all three groups of microplankton, and to correlate the regional dinocyst and planktonic foraminifer zonations to the standard nannofossil scale. Nannofossil zonation of O. Varol’s (1989) is shown to be successfully applied for subdivision of Danian deposits. The large foraminifer assemblage found in the lower Eocene deposits is correlated to the NP12-NP13 zones of the nannofossil scale.     

Metamorphic re-equilibration and metasomatism of highly chromian,garnet-rich peridotitic xenoliths from South African kimberlites

A history of decompression and metasomatism is preserved in a suite of highly chromian, garnet-rich peridotitic xenoliths from the diamondiferous Newlands and Bobbejaan kimberlites, South Africa. A high proportion of the garnets and chromites in these rocks plot in the diamond-facies fields on Cr₂O₃–CaO and Cr₂O₃–MgO wt% plots, and Cr-rich compositions are found in both the harzburgitic and lherzolitic fields. Petrographic evidence suggests that the earliest known mineralogies were those of olivine-bearing, garnet-rich rocks. These were modified by a decompression event that caused recrystallization of garnets and led to orientated spinel and pyroxene inclusions in garnet. Chemical zonation within garnet is divided into (1) external re-equilibration between garnet and matrix; (2) internal re-equilibration between garnet and its inclusions; and (3) metasomatically induced zoning between garnet core and a metasomatic rim. The compositional trajectories associated with zonations (1) and (2) in Ca–Cr plots may be closely modelled by means of sliding, garnet–spinel transition reactions whose slopes vary with bulk Ca composition; at intermediate Ca compositions, the trajectories closely match the slope of the lherzolite line or harzburgite/lherzolite boundary. The decreasing Cr/(Cr + Al) of the garnet in these zonations is in agreement with the evidence for decompression given by the petrographic recrystallization features, and overall decompression of probably 10–20 kb is indicated. We speculate on the age of these events, and consider the possibility of their association with major orogenic events documented by South African crustal rocks at 2.9–2.7 Ga, and events evidenced by peridotite-xenolith Re–Os model ages at 2.8–2.7 Ga.     

On macroseismic attenuation parameters in the comparison of theoretical seismic hazard maps for Southern Calabria and Eastern Sicily (Southern Italy)

For two different zonations of the Calabro-Sicilian region the macroseismic intensity attenuation parameters are computed using the Grandori model.Some modifications to this relation are proposed here in order to allow its applicability also to those cases in which the data set available for each source zone does not present three successive epicentral intensity levels (I ₀) as required for its application.Maps of theoretical distribution of maximum expected intensities were plotted for both zonations adopted, in order to test the reliability, also using other attenuation models.The results of the analysis show how the proposed modifications to the Grandori relation allow the macroseismic intensity attenuation modelling even in cases in which only one intensity level is available.Finally, the comparison of theoretical maximum expected intensity distribution maps, computed for different attenuation models and seismogenic zonations, shows that the maps plotted using the Grandori model and the zonation adopted by G.N.D.T. (Gruppo Nazionale Difesa dai Terremoti - C.N.R. Italy) are more reliable.     

二连盆地巴音都兰凹陷早白垩世构造岩相带特征及含油性

在系统观察岩心的基础上，从单井相分析入手，结合地震相和测井相模式，以及大量岩矿、粒度等分析化验资料，对巴音都兰凹陷下白垩统巴彦花群的物源方向、沉积体系、构造岩相带及含油性进行了研究。认为区内具有东、西两大物源区、五大水系控制着十一个砂体的平面展布，最终，划分了扇三角洲等五种沉积体系，总结出具平台型陡坡扇三角洲等六种构造岩相带，并着重对有别于典型单断箕状凹陷的三种构造岩相带的含油性进行了初步探讨。     

Geochemical characterization and heavy metal contamination of groundwater in Satluj River Basin

Groundwater, a renewable and finite natural resource, vital for man’s life, social and economic development and a valuable component of the ecosystem, is vulnerable to natural and human impacts. The aim of present study is to evaluate hydrogeochemical parameters and heavy metals in groundwater and to study their spatial distribution in the Rupnagar District of Punjab. The spatial distribution of physico-chemical parameters were studied using Arc GIS 9.2. It was observed that the concentration of parameters, such as NO₃, Cd, Cr, Mn and Pb was above permissible limit (World Health Organization, WHO) in southern part of the study area. The heavy metal pollution index (HPI) was calculated for all sampling locations and it was found much above the critical limit of pollution. Geochemical reaction models of selected water groups were constructed using Phreeqc. Geochemical modeling suggests that sodium has source other than halite-albite and calcium has alternate source other than gypsum-carbonate or silicates. It also suggests that evaporites, ion exchange, dissolution along with anthropogenic activities are controlling the hydro-geochemistry of groundwater in the region. Various indices, such as heavy metal pollution index, permeability index, sodium adsorption ratio, were studied to verify suitability of groundwater for drinking and irrigation.