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1.
利用矿物或岩石中铀、钍裂变的碎片径迹来测定铀、钍含量及矿物年令的方法,是裂变径迹法在地质上的应用途径之一。早在1939年就发现铀在受到热中子轰击下,会产生裂变,但一直到1962年普赖斯(Price)等人用蚀刻法把裂变径迹扩大到可用普通光学显微镜进行观察研究之后,裂变径迹法才开始应用到地质研究上来。我国是在最近几年才开始开展这项工作的。1978年我们初次尝试使用诱发裂变径迹法(同时配合其他方法,如重砂分析、中子活化分析和电子探针分析等)确定岩石矿物的铀含量和了解铀在岩石矿物中的配分状况,初步获得了一些有益的结果。 相似文献
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孙嘉彦 《华东地质学院学报》1982,(1)
近年来,随着野外地质普查,地球化学找矿和地质科研工作的需要,对微量铀的测定要求愈来愈多,微量铀(<10PPm)的测定已成为生产和科研中十分重要的分析项目。地质样品(矿样,天然水)中分析微量铀的可用方法较多,有分光光度法、荧光分析法、中子活化法、缓发中子计数法,裂变径迹法和极谱法等等。本文对其应用及近况予以概述与讨论。 相似文献
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裂变径迹定年法中国际标样的年龄测定 总被引：1，自引：0，他引：1
第６届国际裂变径迹测定地质年代学术讨论会上推荐标准化刻度裂变径迹定年法，并推荐了几种定年标样。本文通过标准铀玻璃刻度系数定出值，利用外探测器法测定了国际标样中的３种桔石和两种磷灰石的年龄（ＦＣＴ２７．７±０．８Ｍａ，ＢＭ１６．１±０．５Ｍａ，ＴＲ６０．０±３．ＯＭａ，Ｄｕｒａｎｇｏ３０．８±１．９Ｍａ），在误差范围内与参考年龄一致。 相似文献
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460矿床是火山岩型铀矿床。玻璃包裹体中裂变径迹研究表明:成矿岩体次流纹斑岩的原始铀含量为13.0ppm;裂变径迹测年龄法在强烈蚀变地区可以作为一种测年龄的有效辅助手段。 相似文献
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裂变径迹法在金矿研究中的应用 总被引：9，自引：2，他引：9
用裂变径迹法对湖南平江、浏阳一带含金石英脉人工重砂中的石英进行了年龄测定，以石英的化学蚀刻技术进行了改进，选用６５％ＮａＯＨ蚀刻剂效果较好，石英裂变径迹年龄为１００－１６０Ｍａ，同时还分析了新疆某含金石英脉的铀含量及铀的显微分布。 相似文献
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铀矿γ测井是一种“间接测铀”方法,铀裂变瞬发中子测井是“直接测铀”方法,中子测井技术有其独特的优势,有望替代γ测井技术。经过多年的生产应用,γ测井已经有比较成熟的数据解释软件系统,但是铀裂变瞬发中子测井没有能够投入生产的应用软件。文章根据测井软件系统CIFLog的特点和结构组成,将铀矿测井的五点式反褶积分层解释法通过模块实现,集成于CIFLog系统中,再利用CIFLog测井解释模块,对解释数据进行可视化呈现,生成专业的成果展示,为铀裂变瞬发中子测井的应用提供可靠的应用软件系统。 相似文献
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李小明 《矿物岩石地球化学通报》2001,20(2):136-139
本文对裂变径迹Zeta法定年及应用现状作了简单的介绍。采用国产的铀标准玻璃UB2标定了磷灰石的Zeta常数 ,并对Zeta法的过渡性进行了分析探讨。最后对Zeta法过渡到绝对法提出了粗浅的看法。 相似文献
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B. Masschaele M. Dierick L. Van Hoorebeke V. Cnudde P. Jacobs 《Environmental Geology》2004,46(3-4):486-492
In the paper we present our results for element sensitive high-energy X-ray tomography and high-speed thermal neutron tomography applied to geological samples. The tuneable monochromatic X-ray beam was used for element sensitive tomography of geological samples containing heavy elements using the K-edge dichromatic scanning technique. This type of NDT (non-destructive testing) allowed us to reveal the quantity and location of uranium, lead and mercury in Oklo samples (natural nuclear reactor) and Cinnabar stones. Fast 3-D thermal neutron imaging of dynamical processes was successfully tested at the high flux neutron tomography station of the ILL. The qualitative investigation of water repellents and consolidants applied on sandstones of Bray and limestones of Maastricht were the first samples to be studied with the new imaging technique. 相似文献
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Philippe Lach Julien Mercadier Jean Dubessy Marie‐Christine Boiron Michel Cuney 《Geostandards and Geoanalytical Research》2013,37(3):277-296
Advances in the quantification of rare earth elements (REE) at the micrometric scale in uranium oxides by laser ablation‐inductively coupled plasma‐mass spectrometry are described. The determination of the best analytical conditions was tested using a uranium oxide (Mistamisk) the concentrations of REE in which were previously estimated by other techniques. Comparison between the use of U or Pb as an internal standard clearly showed a diameter‐dependent fractionation effect related to Pb at small crater diameters (16 and 24 μm), which was not found for U. The quantification of REE contents in uranium oxide samples using both matrix‐matched (uranium oxide) and non‐matrix‐matched (NIST SRM 610 certified glass) external calibrators displayed no significant difference, demonstrating a limited matrix effect for REE determination by LA‐ICP‐MS. Moreover, no major interferences on REEs were detected. The proposed methodology (NIST SRM 610 as external calibrator and U as internal standard) was applied to samples from uranium deposits from around the world. The results showed that LA‐ICP‐MS is a suitable analytical technique to determine REE down to the μg g?1 level in uranium oxides at the micrometre scale and that this technique can provide significant insights into uranium metallogeny. 相似文献
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凹凸棒石粘土吸附铀的性能研究及应用 总被引：34，自引：2，他引：32
本文研究了凹凸棒石粘土吸铀的酸度,吸附速率、肿附反应热焓吸附容量等性能,确定了吸附铀的最佳条件,并采用动态法片处理了含铀废水,效果良好,钱的去除率在９９．９５％以上,排放液中的铀的残余浓度达到国家规定的０．０５ｍｇ／Ｌ排放标准。 相似文献
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华东某铀矿区稻米中Cd含量及空间分布特征研究 总被引：2，自引：0，他引：2
利用等离子体质谱仪测定了某铀矿区周边稻米与对照区稻米中重金属元素Cd的含量,重点对铀矿区稻米中的Cd元素含量及其空间分布特征进行了研究。结果表明:(1)铀矿区内10.53%的稻米样品Cd含量超过国家标准,89.47%稻米样品中Cd的含量未超过国家标准(GB 2762-2005),而对照区稻米样品中Cd含量均远低于国家标准(GB 2762-2005);(2)铀矿区稻米中Cd含量远高于对照区稻米中Cd含量,尾矿堆积区、水冶厂和矿床开采区下游及周边区域内稻米中Cd元素含量明显高于上游地区或远离上述区域的其他地区。(3)矿床开采产生的废水与废渣、水冶厂的废液渗漏、尾矿露天堆积以及矿石运输过程中的矿渣洒落等原因可能是导致Cd元素随地表径流发生迁移进入稻田,从而使矿区稻米中Cd的含量较高的重要因素。 相似文献
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六溴环十二烷(HBCDs)是一种全球生产的添加型溴化阻燃剂,被广泛应用于隔热建筑材料阻燃剂、室内装潢、纺织品和电子产品中,不仅对生态环境造成污染,而且还会通过食物链的传递危害人类健康。研究生态系统中HBCDs异构体及对映体的环境行为与生物放大作用是进行环境风险评估和有效控制污染的生态学基础。基于此,本文从HBCDs的基本特性出发,阐述了HBCDs异构体及对映体在食物链中的选择性生物富集放大及转化行为,分析了发生选择性富集及转化的影响因素,这些因素包括生物体的生活环境、饮食习惯、所处食物链中营养级水平以及HBCDs选择性吸收、代谢和异构化等。已有的研究报道显示HBCDs异构体及对映体在生态系统中的富集、转化及生物放大行为不是单一的过程,是生物体和环境多因素综合的结果。今后应对HBCDs异构体及对映体在各种食物链(如淡水食物链和陆生食物链)中的选择性环境行为以及在食物链传递中发生选择性的主控因素等方面进行深入系统的研究,为全面评价其生态风险提供科学依据。 相似文献
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Tuffaceous sediments as source rocks for uranium: A case study of the White River Formation, Wyoming
Robert A. Zielinski 《Journal of Geochemical Exploration》1983,18(3):285-306
Fine-grained tuffaceous sediments of the White River Formation (Oligocene) are evaluated as a possible source of uranium for the sedimentary uranium deposits of Wyoming. The evaluation is based upon a model in which volcanic glass is considered to be a major host of uranium and thorium and in which uranium and silica are released during alteration of glass to montmorillonite. The evaluation scheme is applicable to other tuffaceous sediments in similar geologic settings. The average uranium and thorium contents of glass separates and glassy air-fall ashes of the White River Formation are 8 ppm and 22.4 ppm respectively, and these values approximate the average composition of glass deposited in Wyoming basins in Oligocene time. Comparison of these values with the uranium and thorium concentrations in montmorillonite separates indicates little change in thorium concentrations but reductions in uranium concentrations which average 3.3 ppm. In spite of the apparent major removal of uranium during alteration of glass to montmorillonite, whole-rock samples of tuffaceous siltstones show an average uranium loss of only 0.4 ± 0.4 ppm, because of generally small amounts of clay alteration. This conclusion is generated by comparisons between glassy ash and partially altered vitric siltstones, the latter corrected for dilution of glass and clay-altered glass with uranium- and thorium-poor primary and detrital materials. The original volume of the White River Formation is adequate to generate economically significant quantities of mobile uranium, even with such modest losses. Uranium and silica which are mobilized during glass alteration can coprecipitate as uraniferous secondary silica in areas where solutions become silica saturated. These precipitates indicate pathways of ancient, uranium-rich solutions in tuffaceous rocks. Exploration efforts in the White River Formation and underlying units should concentrate on areas where such pathways intercept reducing environments. Intercepts of this type are present at some uranium deposits in the study area and this lends support to a tuffaceous source rock model. 相似文献
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E.I. Hamilton 《Chemical Geology》1975,16(3):221-231
The abundance and distribution of uranium in various continental and oceanic ultramafic inclusions and host basalts are reported. Uranium was determined by neutron activation (fission products, fission tracks and delayed-neutron methods) and alpha-particle autoradiography; data is also reported for the uranium content of various USGS standard rock powders. The concentration of uranium in both oceanic and continental samples is similar, levels are controlled by mineral compositions, and their relative abundance in different rock types. Highest levels are found in feldspathic and lowest in olivine rich inclusions. Uranium is enriched in mylonitised samples and along some inter-crystal boundaries. With the exception of some apatites, highest levels of uranium are in clinopyroxenes (chrome) and lowest in olivines; no enrichment of uranium in orthopyroxenes was observed. Attention is drawn to the problem of obtaining representative samples from the sea floor which have not been altered by saline solutions and the identification of uranium and daughter products present along inter-crystal boundaries. Differences in observed heat flow between continental and oceanic areas may reflect inadequate sampling of representative rock types present below the sea floor and lack of information for the true abundance and distribution of uranium in such rocks. 相似文献
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介绍了地—空界面天然中子流的来源和轻便型天然中子流测量仪器。论述了地—空界面天然中子辐射场的扰动。理论与长期观测表明,在地—空界面上天然中子流注量率随高程的增加而呈指数规律增加,而在近地表(20m内)却随距地面高度的增加而呈指数规律减少;天然中子流注量率与大气压力呈负相关关系,气压系数为(-0.060～-0.064)中子计数/30min/kPa;地—空界面天然中子流的纬度效应与高空中更显著;天然中子流注量率异常与气象的变化密切相关;地表介质的含水率增高,则地—空界面上升快中子流明显降低。通过对地一空界面天然中子流测量,可以揭示气象的瞬态变化、确定地表介质的含水率的关系,以及在地震预报与环境电离辐射评价方面具有重要的科学意义与实用价值。 相似文献
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Humberto Terrazas Salas Hermínio Arias Nalini Jr. Júlio César Mendes 《Environmental Geology》2006,49(4):520-526
One hundred samples of granitic rock were collected from granite traders in Belo Horizonte. Autoradiography, optical microscopy,
diffractometry, and chemical analysis (X-ray spectrometry, X-ray fluorescence, neutron activation, gravimetry, and electron
probe microanalysis) were used to determine the mineral assemblages and lithotypes. Autoradiographic results for several samples
showed the presence of monazite, allanite, and zircon. Chemical analysis revealed uranium concentrations ≤30 ppm and thorium
≤130 ppm. Higher concentrations generally correlated with high concentrations of light rare earths in silica-rich rocks of
granitic composition. Calculations were made of radioactive doses for samples, of floor tiles in a standard room, with total
concentration of uranium and thorium greater than 60 ppm. On the basis of calculations of 232 Th, 40 K, and 226 Ra from analysis of Th, K, and U, the doses calculated were between 0.11 and 0.34 mSv/year, which are much lower than the
acceptable international exposure standard of 1.0 mSv/year. 相似文献