共查询到20条相似文献，搜索用时 531 毫秒
1.
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砂岩,整体发育一系列后生蚀变。研究区北东侧安南坝山古元古界达肯达坂群及赛什腾山海西期花岗岩为区内砂岩型铀成矿提供了丰富的铀源。砂岩型铀矿中铀主要以独立铀矿物沥青铀矿的形式赋存,其次含有少量分散吸附态铀,沥青铀矿总体呈不规则粒状、星点状、"串珠状、线状"及粉末状赋存于黄铁矿边缘、裂隙部位或黄铁矿与方解石的接触部位,吸附态铀主要赋存于炭屑及煤线内;区内沥青铀矿为柴北缘地区首次揭露并发现的独立铀矿物,总体上填补了柴北缘地区无独立铀矿物出露的空白。铀成矿条件方面,含矿目的层中方解石的发育,显示了铀成矿流体富含CO_2、H_2O等挥发分和矿化剂,其次出露的众多还原性介质(油气、炭屑及黄铁矿等)为区内砂岩型铀成矿提供了氧化还原反应必需的还原剂,最终将U~(6+)还原成U~(4+)以沥青铀矿等形式沉淀成矿。 相似文献
2.
为揭示尼日尔阿泽里克铀矿床成矿物质来源,文章研究了其蚀变特征、稀土元素特征、流体包裹体特征、方解石胶结物碳和氧同位素特征、沥青铀矿氧同位素特征等。阿泽里克铀矿床发育灰绿色还原蚀变、方沸石化、酸性火山玻璃脱玻化、碳酸盐化、黄铁矿化、重晶石化等。矿化砂岩稀土元素Eu强正异常。流体包裹体气体成分为H2+N2+CO2组合。方解石胶结物的δ13CV-PDB值为-7.45‰～-6.65‰,δ18OV-SMOW值为-0.74‰～1.26‰。沥青铀矿的δ18OV-SMOW值为-1.30‰～-0.8‰。灰绿色还原蚀变岩石呈灰绿色是因为绿泥石矿物充填粒间孔隙和包裹颗粒表面。矿化砂岩的Eu强正异常揭示有来自深部的强还原性流体参与成矿。H2为强还原物质,来自深部,可为铀成矿提供还原剂。矿化砂岩方解石胶结物碳同位素显示成矿流体有深部流体的作用,可能有地幔物质的加入;氧同位素显示成矿流体有表生流体的作用。沥青铀矿氧同位素值显示成矿流体受表生大气水作用影响。酸性火山物质方沸石化和酸性火山玻璃脱玻化为铀成矿提供铀。成矿流体为表生氧化性流体与深部的还原性流体的混合。总之,地层、阿伊尔花岗岩和火山物质可能为铀成矿提供了铀。 相似文献
3.
鄂尔多斯盆地北部中侏罗统直罗组富铀砂岩成岩过程复杂,铀成矿并非典型的层间氧化带模式。通过对盆地北部杭锦旗地区矿化砂岩成岩矿物、方解石碳氧同位素、流体包裹体的综合分析,探讨了杭锦旗砂岩型铀矿的流体作用特征与铀成矿过程。结果表明:矿区砂岩遭受碱性渗入水、烃类降解酸性水、碱性热液3种类型流体作用;碱性热液为最晚期的流体活动,亮晶方解石捕获的原生流体包裹体均一温度峰值为140~160℃,盐度为8.00%~16.34%,方解石δ13C明显偏负(-7.1‰~-18.3‰),为有机来源碳参与的高盐度碱性热流体。前人证实盆地北部砂岩型铀矿具有生物成因特征,与热液活动相悖;结合铀元素迁移特征,认为热液活动与微生物还原作用并不矛盾,碱性热液改变了矿区砂岩流体的物理化学环境,稳定络合物的形成对铀元素具有萃取再富集作用;热液活动是富矿流体形成的关键事件,微生物活动在热液活动停止后直接参与铀还原成矿。 相似文献
4.
通过对特吉达地区已知矿床的铀矿找矿模型研究,为该区在矿区外围进一步开展铀矿预测工作提供依据。根据本次物探测量,结合地质、测井等资料,认为:矿体位于下白垩统阿萨乌阿组砂岩中,受区域性断裂控制,常产在古生界隆起的边缘;不同埋深矿体的地球物理场特征各异,但总体表现为车载(地面)伽马能谱测量有铀异常显示,活性炭吸附氡测量有氡浓度异常显示,土壤天然热释光测量有热释光强度异常显示,音频大地电磁(AMT)测量显示矿体位于低阻向中阻变化部位、且靠近中阻一侧。以此为基础,预测了5片铀矿找矿靶区,其中的2片经后期勘查,发现铀矿化(线索)。 相似文献
5.
蒙其古尔铀矿床为伊犁盆地南缘大型层间氧化带砂岩型铀矿床,为查明该矿床含矿层中黄铁矿成因及其形成机制,探讨微生物参与铀成矿过程。文章对含矿层砂岩中黄铁矿与铀矿物矿物学特征、黄铁矿S同位素与碳酸盐胶结物的C-O同位素开展细致研究。研究表明:①蒙其古尔铀矿床中铀主要以铀矿物与吸附铀形式存在,吸附铀主要为有机质吸附铀,铀矿物以沥青铀矿为主,多与黄铁矿、炭屑共生;②蒙其古尔铀矿床含矿层砂岩中黄铁矿主要以自形晶、草莓状和不规则状集合体产出,多与沥青铀矿、碳酸盐胶结物共生,其中黄铁矿S同位素(δ~(34)S_(V-CDT)=-68.4‰～22.1‰)与碳酸盐胶结物的C-O同位素(δ~(13)C_(V-PDB)=-10.2‰～-7.4‰,δ~(18)O_(V-PDB)=-9.6‰～-5.8‰)分析表明黄铁矿具有细菌硫酸盐还原(BSR)与有机物热解2种成因,并探讨了这2种不同成因黄铁矿的形成机制。③结合前人研究成果,认为硫酸盐还原菌(SRB)参与蒙其古尔铀矿床铀成矿过程,以间接还原方式为主,在有机质、黏土矿物与颗粒表面吸附U(Ⅵ)的基础上,通过硫酸盐还原菌(SRB)还原SO_4~(2-)产生的H_2S将U(Ⅵ)被还原成U(Ⅳ),形成铀矿物。 相似文献
6.
为了进一步深化铀矿物的富集机理.利用α径迹放射性照相、扫描电镜、电子探针等方法对鄂尔多斯盆地北部铀矿床中铀矿物的赋存状态进行了系统研究.发现该区铀矿物主要为铀石，少量沥青铀矿和含铀钛矿物.沉积-成岩期碎屑铀矿物赋存在碎屑颗粒内部，吸附在锐钛矿周围，为铀储层中预富集的铀.成矿期铀矿物大部分赋存在碎屑颗粒填隙部位，与黄铁矿、碳质碎屑相伴生，与石英颗粒及方解石胶结关系密切；部分吸附在包裹碎屑颗粒的蒙脱石薄膜上.另外发现了，沥青铀矿-赤铁矿-黄铁矿的矿物组合，以及硒铅矿（PbSe）和白硒铁矿（FeSe2）与铀矿物相伴生，并伴有REE含量明显升高.分析得出，沥青铀矿形成于成矿早期，氧化酸性流体与还原碱性流体的过渡界面，偏向于氧化酸性一侧；而铀石主要形成于成矿晚期的还原碱性环境.双重铀源供给、丰富的还原介质、多源流体的耦合，局部的热液流体叠加改造，共同造就了鄂尔多斯盆地北部大矿、富矿的形成. 相似文献
7.
彭阳铀矿位于鄂尔多斯盆地西南缘, 是全球首例在风成沉积环境中发现的大型砂岩型铀矿, 具有含矿层位深、砂体厚度大、铀矿品位高等特点。通过对彭阳铀矿地质特征、物源、铀源、铀矿物赋存状态、蚀变矿物、烃类流体参与成矿等方面进行研究, 结合前人研究成果, 系统总结了彭阳铀矿的成矿规律。综合研究表明, 研究区深大断裂发育、拥有厚大砂体及稳定的“泥-沙-泥”结构, 对铀成矿极为有利。同时, 盆地西缘岩体可提供稳定铀源, 浅层富氧含铀流体顺层流动、下渗, 深部烃类流体沿断裂上升至洛河组, 导致红色砂岩褪色蚀变, 为铀成矿提供还原剂。中新世到更新世, 构造活动引发了富氧含铀流体和深层含烃流体的耦合作用, 形成了完整的“补-径-排”流体成矿系统, 最终导致铀成矿。通过分析彭阳铀矿的成矿和控矿要素, 进而建立了成矿模式, 对鄂尔多斯盆地西南缘砂岩型铀矿找矿及其它地区相似地质条件下找矿勘查与研究具有重要指示意义。 相似文献
8.
鄂尔多斯盆地东北缘侏罗系铀矿化与有机质的某些关联 总被引：5，自引：0，他引：5
许多中—新生代盆地沉积充填中铀矿化显著,有机质丰富,铀矿与有机能源同盆共存,铀矿化与有机质内在关联备受关注。鄂尔多斯盆地东北缘东胜—准格尔旗地区侏罗系直罗组下部铀矿化砂岩平均铀含量（128.4×10-6）高出含铀泥岩2个数量级,铀富集成矿以砂岩为主岩并伴随显著的方解石化、高岭石化等低温热液蚀变;铀矿化岩层富有机质,其氯仿沥青“A”中非烃和沥青质占优势,饱和烃/芳香烃比值多大于1,Ⅱ型有机质为主。铀矿化砂岩的有机碳平均丰度（0.47%）比含铀泥岩低1个数量级,前者铀含量与有机质丰度呈负相关,有机质的氯仿沥青“A”含量0.0056%~0.0341%、A/C比值为0.79%~32.34%,处在成熟阶段;而后者铀含量与有机质丰度呈正相关,有机质的氯仿沥青“A”含量0.0049%~0.4937%、A/C比值为0.12%~17.78%,处在未成熟阶段。砂岩中铀富集成矿明显经历了伴随有机质氧化、成熟和分解的晚成岩—后生期含铀热液过程,而泥岩中的铀主要是同生—早成岩阶段粘土有机吸附沉积的。铀矿化砂岩中热液蚀变方解石的δ13CVPDB =-2.7‰～-14.0‰,δ18OVSMOW =18.4‰～20.0‰;热液蚀变高岭石的δ18OVSMOW= 12.6‰～13.8‰,δD(水)VSMOW=-116‰～-133‰,与高岭石平衡流体的δ18O(水)VSMOW =1.8‰～6.1‰,指示含铀成矿热液中CO2主要是有机质氧化脱羟基产物,水来自经过富含有机质地层循环演化了的盆地流体。研究区盆地流体中铀元素在砂岩层内流动和沉淀成矿与地层中有机质的氧化分解相伴发生。 相似文献
9.
龙虎泡铀矿化区的发现是近年来根据油田资料二次开发和钻探验证而取得的重要创新成果之一,矿化区位于松辽盆地北部龙虎泡-大安阶地北,西与泰康隆起区和西部超覆区相邻。本文在详实的野外工作基础之上,利用偏光显微镜、电子显微镜、能谱、背散射、点化学分析及元素面扫描分析等手段,对龙虎泡地区含铀砂岩中以钛铁矿及其相关蚀变矿物为代表的铁钛氧化物与砂岩型铀矿化之间的关系进行了研究探讨,结果表明:①以富铀-铁钛氧化物-钛氧化物-黄铁矿为代表的蚀变矿物共生组合记录和保留了有关砂岩型铀矿成矿流体和成矿环境的重要信息,含矿砂岩中钛铁矿及其蚀变相关的富铀-铁钛氧化物、钛氧化物、黄铁矿等矿物的不同产出类型和不同蚀变矿物共生组合关系对比分析指示,龙虎泡地区铀成矿受到了后期含铀富铁的氧化性流体与富H_2S的还原性流体混合作用影响,成矿环境偏强还原;②与铀矿化关系最为密切的铁钛氧化物是蚀变程度高且富镁的钛铁矿,富铀-铁钛氧化物即是这些强蚀变钛铁矿与后期成矿流体发生氧化还原作用形成的,钛铁矿内部溶蚀裂隙为含矿流体的蚀变和铀的沉淀富集提供了良好的容矿空间,蚀变钛铁矿和黄铁矿为铀的沉淀富集分别提供了良好的矿物尺度上的氧化障和还原障,在含矿流体与富H_2S还原性流体混合过程中,铀得以在蚀变钛铁矿与黄铁矿的氧化还原界面附近沉淀富集。 相似文献
10.
11.
S. Viswanathan K. Surya Prakash Rao B. Mahabaleswar 《Journal of the Geological Society of India》2013,82(6):621-627
Komatiites are mantle-derived ultramafic volcanic rocks. Komatiites have been discovered in several States of India, notably in Karnataka. Studies on the distribution of trace-elements in the komatiites of India are very few. This paper proposes a simple, accurate, precise, rapid, and non-destructive wavelength-dispersive x-ray fluorescence (WDXRF) spectrometric technique for determining Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in komatiites, and discusses the accuracy, precision, limits of detection, x-ray spectral-line interferences, inter-element effects, speed, advantages, and limitations of the technique. The accuracy of the technique is excellent (within 3%) for Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Zr, Nb, Ba, Pb, and Th and very good (within 4%) for Y. The precision is also excellent (within 3%) for Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th. The limits of detection are: 1 ppm for Sc and V; 2 ppm for Cr, Co, and Ni; 3 ppm for Cu, Zn, Rb, and Sr; 4 ppm for Y and Zr; 6 ppm for Nb; 10 ppm for Ba; 13 ppm for Pb; and 14 ppm for Th. The time taken for determining Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in a batch of 24 samples of komatiites, for a replication of four analyses per sample, by one operator, using a manual WDXRF spectrometer, is only 60 hours. 相似文献
12.
13.
奥地利安东帕有限公司 《岩矿测试》2009,28(3):306-306
最新的流行病学研究表明,空气中较高浓度的悬浮细颗粒可能对人类的健康有不利的影响。根据该项研究显示,由于心脏病、慢性呼吸问题和肺功能指标恶化而导致死亡率的升高与细尘粒子有关。这些研究结果已经促使欧盟于1999年4月出台了限制空气中二氧化硫、二氧化氮、氧化氮、铅和颗粒物含量的法案(1999/30/EC),对各项指标包括对可吸入PM10颗粒的浓度提出了新的限制性指标。PM10颗粒是指可以通过预分级器分离采集的气体动力学直径小于10μm的细颗粒。目前研究的兴趣重点逐步偏向PM2.5这些更细微颗粒物,PM2.5这种颗粒物对健康有明显的不利影响。在欧盟指令2008/50/EC中,对PM10和PM2.5都提 相似文献
14.
E. M. Prasolov S. A. Sergeev B. V. Belyatsky E. S. Bogomolov K. A. Gruzdov I. N. Kapitonov R. Sh. Krymsky V. O. Khalenev 《Geochemistry International》2018,56(1):46-64
This paper reports the first results of a study of 11 isotope systems (3He/4He, 40Ar/36Ar, 34S/32S, 65Cu/63Cu, 62Ni/60Ni, 87Sr/86Sr, 143Nd/144Nd, 206–208Pb/204Pb, Hf–Nd, U–Pb, and Re–Os) in the rocks and ores of the Cu–Ni–PGE deposits of the Norilsk ore district. Almost all the results were obtained at the Center of Isotopic Research of the Karpinskii All-Russia Research Institute of Geology. The use of a number of independent genetic isotopic signatures and comprehensive isotopic knowledge provided a methodic basis for the interpretation of approximately 5000 isotopic analyses of various elements. The presence of materials from two sources, crust and mantle, was detected in the composition of the rocks and ores. The contribution of the crustal source is especially significant in the paleofluids (gas–liquid microinclusions) of the ore-forming medium. Crustal solutions were probably a transport medium during ore formation. Air argon is dominant in the ores, which indicates a connection between the paleofluids and the atmosphere. This suggests intense groundwater circulation during the crystallization of ore minerals. The age of the rocks and ores of the Norilsk deposits was determined. The stage of orebody formation is restricted to a narrow age interval of 250 ± 10 Ma. An isotopic criterion was proposed for the ore-bearing potential of mafic intrusions in the Norilsk–Taimyr region. It includes several interrelated isotopic ratios of various elements: He, Ar, S, and others. 相似文献
15.
Mining induced subsidence can significantly affect mining costs where major surface facilities and natural environment need to be protected. Overburden grout injection is a technology used to control coal mine subsidence by injecting the mine waste material extracted from the coal back into the inter-burden rock during longwall mining. The flowing slurry is here categorised as a nonlinear viscous cohesive (Bingham plastic) fluid. During longwall mining the grout slurry is pumped into the separated beds of the rock mass through a central vertical borehole, which is drilled deep into the inter-burden rock strata above the coal seam. However, a blockage can occur in the injection system when the slurry velocity falls below a certain critical threshold velocity, indicating a material phase change from cohesive-viscous to cohesive-frictional. In situ field injection tests through boreholes have been simulated at a smaller scale at the CSIRO laboratory in Brisbane by pumping the slurry through a radial disk (gap = 4 mm) from its centre. Laboratory experiments indicate a general, nonlinear, cohesive, viscous, frictional model for shear behaviour of the slurry, in which the material shear parameters are functions of the disk radial distance. Complete dimensional and dimensionless analytical solutions have been developed based on an approach related to Bingham–Herschel–Bulkley fluid mechanics. The derived formulae include relations for minimum pump pressure, local pressure and pressure gradient, wall shear stress, volume rate, velocity and velocity gradient. The theoretical results match the experimental measurements. The experiments covered slurries with maximum particle sizes of 0.5 to 2 mm with about 50% being larger than 100 µm. The viscosities at the various solids concentrations were measured with a standard torsion viscometer. This study differs from the previous research in several distinct aspects, namely, consideration of the variable shear parameters rather than fixed values, inclusion of total nonlinear behaviour, and implementation of a friction function to mimic behaviour of the deposited and consolidating stiff slurry, which can cause a significant pressure rise as a result of the increased shear resistance. 相似文献
16.
17.
Alexander E. C. Broberg J. S. Kehren A. R. Graziani M. M. Turri W. L. 《Environmental Geology》1993,22(4):353-361
Bellechester, Minnesota, is a small community of approximately 155 residents located on the county line between Goodhue and Wabasha counties in southeast Minnesota's karst region. Bellechester is served by a 21-year-old wastewater treatment facility (WWTF) consisting of three waste-stabilization ponds. On 28 April 1992 six sinkholes were discovered to have drained cell 2 of the WWTF resulting in the loss of approximately 8.7×106 1 of partially treated effluent and about 600 m3 of soil into previously undetected subsurface voids of unknown dimensions. In the week following the collapse, approximately 200 water wells located within a 5-km radius of the WWTF were sampled in an after-the-fact, emergency sampling program. Twelve samples with elevated fecal coliform levels, 18 samples with nitrate-nitrogen greater than the 10 mg/1 standard, and no samples with elevated chlorides were found. However, the elevated levels could not be unambiguously attributed to the WWTF collapse. This is the third WWTF to fail by sinkhole collapse in southeast Minnesota since 1974. All three collapsed lagoons have been located in similar geomorphic and stratigraphic settings. However, at least two lagoons have collapsed in the adjacent area in northeast Iowa, and these lagoons are located at different stratigraphic positions. Twenty-two WWTFs constructed in southeast Minnesota's karst region in the last 25 years have been identified as subject to potential sinkhole collapse. An unknown but significant number of manure storage lagoons, flood control structures, etc., have also been constructed in the karst region and are at risk. Public agencies are beginning to develop plans to deal with the risk associated with existing and future waste lagoons in this environment. The critical hydrogeologic parameters that can be used to prioritize the risk of collapse at existing facilities include: (1) the lithology of the first bedrock beneath each lagoon, (2) the thickness of surficial materials between the lagoon and the bedrock surface, (3) the presence and construction of liners (seepage rate), and (4) the proximity to existing sinkholes. 相似文献
18.
滇东南锡、银、铅、锌多金属矿床主要分布在个旧、白牛厂、都龙3个矿区,而滇东南较大的3个花岗岩体又分别出露在3个矿区或附近.花岗岩体均形成于燕山晚期,岩石化学、矿物成分相似,富含锡、银、铅、锌、钨、铜等成矿元素.矿床主金属元素组合与岩体之间的距离由远而近出现由锡、钨、(铍、铌、钽)→锡、钨、(铁)、铜、铟→锡、铅、锌、银、铟、(锑)有规律的变化.花岗岩浆是成矿物质来源和成矿热源.岩浆侵入初期使上覆地层隆起产生背斜(凹陷部位成向斜);同时使地层产生一系列裂隙、压性断层或层间断裂;岩浆侵入晚期,这些断层再次活动,表现为张性,岩浆产生的含矿热液沿由其活动所造成的断裂迁移、充填、交代、沉淀而形成矿床. 相似文献
19.
Mercury,arsenic, antimony,and selenium contents of sediment from the Kuskokwim River,Bethel, Alaska,USA 总被引：1，自引：0，他引：1
The Kuskokwim River at Bethel, Alaska, drains a major mercury-antimony metallogenic province in its upper reaches and tributaries. Bethel (population 4000) is situated on the Kuskokwim floodplain and also draws its water supply from wells located in river-deposited sediment. A boring through overbank and floodplain sediment has provided material to establish a baseline datum for sediment-hosted heavy metals. Mercury (total), arsenic, antimony, and selenium contents were determined; aluminum was also determined and used as normalizing factor. The contents of the heavy metals were relatively constant with depth and do not reflect any potential enrichment from upstream contaminant sources. 相似文献
20.
岩石密度和超高压岩石折返速率 总被引：1，自引：3，他引：1
在常温常压条件下对中国大陆科学钻CCSD主孔100-3000米岩心样品进行了密度测量,建立了密度连续剖面,并界定了不同超高压岩石的密度值。通过对比高温高压物性实验资料,岩石密度随着退变程度增强而降低,榴辉岩密度变化序列为3.52g/cm3→3.49g/cm3→3.07g/cm3→2.93g/cm3。超高压长英质岩石密度变化序列为3.00g/cm→2.80g/cm3→2.65g/cm3。上述实验资料是讨论不同折返阶段岩石所受浮力的基础,为研究折返速率大小提供了基本参数。本文通过折返板块运动平衡时,上浮力与粘滞力平衡这一关系式,定量研究了大陆俯冲板块的折返速率,认为密度差产生上浮力从而引起折返,温度对板块折返速率的影响最为显著;密度差大小、折返角度、折返板块大小对折返速率也有直接的影响。定量模拟分析表明,在温度高于850℃时,板块的折返速率可以超过100mm/a;当温度降至700℃时,折返速率则低于1.5mm/a。作者认为在折返早期,温度较高,板块快速折返至60-70km榴辉岩相深度;随着传导散热,温度降低,板块以较慢的速率折返至中下地壳。折返速率的估算表明,浮力是板块折返第一阶段(从>100km深部折返至<40km的中下地壳)的主要驱动力。 相似文献