共查询到20条相似文献,搜索用时 15 毫秒
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J. Sen N. Ranganath Y.V. Rathaiah D. B. Sen S. N. Kak 《Journal of the Geological Society of India》2009,74(5):639-645
During radiometric investigation at Mawlait, significant uranium mineralisation (0.024–0.22%U3O8) was located mainly within the small pegmatite (garnet bearing quartzofeldspathic rock), which are locally segregated within
migmatite at Umiang River section. Pink granite and granite gneisses are the dominant lithounits of the study area showing
fertile character and spotty radioactivity at several places. Radioactivity in these rocks is mainly contributed by discrete
uraninite grains along with some zircon and xenotime. Granites are peraluminous, low-Ca in nature and their geochemical signatures
suggest derivation from a felsic source. Discriminant diagrams using Rb, Nb and Y indicate ‘within plate’ to ‘volcanic arc’
nature of the rock. The uraniferous pegmatitic veins within migmatite appear to have formed due to localised metamorphic segregation
during late stage of anatexis. Petromineralogical and geochemical studies suggest that the uranium mineralisation in granitic-pegmatitic
rocks of the area is mainly syn-magmatic type. 相似文献
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我国航空放射性测量的进展 总被引:3,自引:0,他引:3
本文概述了我国航空放射性测量在铀矿普查中取得的地质找矿成果和今后工作设想。文中全面而简要地综述了近10年来我国航空放射性测最在仪器设备、技术方法、标定设施、资料研究和综合找矿等方面的进展情况。 相似文献
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Groundwater in contact with ore deposits may acquire a chemical composition that could be used as a guide for exploration. Eight well-water samples are collected from a known uranium-mineralized area near Abu Zenima, west central Sinai to examine the applicability of using the hydrogeochemical technique in the search for uranium mineralization in similar arid areas. The analytical chemical data of the ground water is compared with ground radiometric measurements. The obtained results indicate that groundwater affected by uranium mineralization has a specific relativity of major anions expressed essentially as SO4>Cl>HCO3 and to a lesser extent as Cl>SO4>HCO3, associated as a rule with low magnesium content. This association constitutes a signature of uranium mineralization on the composition of groundwater in west central Sinai and could be used as an important exploration guide in the search for uranium deposits in similar areas. Anomalies in Ni, Fe, Zn and Cr and other pathfinder elements in groundwater can furnish geochemical guides to uranium ores. The immobile trace element anomalies, including Zn, Ni and Fe are strongly distributed near the orebody; whereas the relatively mobile trace elements, including Co, U, V and Cr, constitute the dispersion haloes away from the orebody. A new hydrogeochemical discrimination diagram is constructed to be used as a quick and cost effective exploration tool in the search for uranium occurrences in environmentally similar arid areas. Based on the obtained results, a new site for uranium occurrence, west of W. Baba, is delineated and recommended for future detailed geological and geochemical surveying. 相似文献
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S.J. Hoffman 《Journal of Geochemical Exploration》1983,19(1-3)
The Hornby Bay sandstone basin of the Northwest Territories represents one of three areas in Canada in which the geological environment is favourable for the occurrence of unconformity-type uranium deposits. The project area lies within the zone of continuous permafrost and is associated with relatively thin and locally derived tills and abundant outcrops. Topographic relief is normally in the order of 100 m but may locally exceed 300 m/km in more rugged areas.Geochemical case histories for soil and lake-sediment surveys illustrate: identification of regional anomaly, anomaly follow-up, and detailed investigations. Success in locating uranium occurrences using geochemical surveys is high. Orientation studies trace anomalous dispersion trains 10 to 200 m downslope of recognized sources. Anomaly generation is favoured by active hydromorphic processes in geochemically homogeneous overburden containing an average background of 0.5 ppm uranium (using a 4N nitric acid leach). Anomaly contrasts are typically 2 Xto 3 X this value, and anomalous values exceeding 1.5 ppm uranium are highly reproducible.Copper and radium anomalies act as pathfinders for uranium. Lead is present in anomalous concentrations in specimens from the uranium occurrences but lead enrichment in overburden is not sufficiently great to permit its use as a pathfinder element. Preliminary work based on radon and 210Po has not led to identification of anomalies other than those recognized by more routine geochemical surveys.Association of geochemical anomalies with faults within the sandstone basin constitutes one of four conditions elevating an area to drill target status. Methods for drill testing of geochemical soil anomalies depend on the relationship between the geochemical anomaly and an identifiable fault zone. 相似文献
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Rajeev Menon P. V. Sunder Raju G. K. Reddy 《Journal of the Geological Society of India》2009,74(1):23-26
A geochemical soil sampling survey undertaken at Tumallpalle uranium mineralized zone Cuddapah district, has confirmed the
presence of uranium anomalies in soils. Bulk soil samples were collected at every 20 m along the traverse from approximately
30 cm below the surface and were assayed for uranium by x-ray fluorescence (XRF) and inductively coupled plasma mass spectrometry
(ICP-MS). The uranium anomalies detected by the insitu radiometric survey show a correlation with the helium highs. The soil
gas helium studies have aided in delineating the subsurface extension of the deposit. This study endeavors for an integration
of different techniques in a known area which could probably aid in delineating uranium zones for optimal exploitation in
the future exploration programmes. 相似文献
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中国东部中生代岩浆岩的时空分布及其与热液型铀矿的关系 总被引:4,自引:2,他引:2
中国东部中生代岩浆活动强烈,热液型铀矿分布广泛。空间上,自北而南可划分出大兴安岭、小兴安岭-长白山、冀北-辽西、大别山北缘、长江中下游、扬子陆块东南缘、武夷-云开、东南沿海8个火山-侵入岩带和沽源-红山子、青龙-兴城、庐枞-栖霞、赣杭、武夷山、桃山-诸广、郴州-钦州、湘中、雪峰山-摩天岭9个热液型铀成矿带以及满洲里-额尔古纳、扎兰屯、伊春、金寨、天目山5个铀成矿远景带;时间上,从早到晚可划分出250~230Ma、228~205Ma、195~175Ma、165~150Ma、145~130Ma、126~115Ma、110~100Ma、97~80Ma 8个不同时期的岩浆活动和早期深源高温、晚期浅源低温两个成矿系统,深源高温成矿系统可划分出11个矿床式,浅源低温成矿系统可划分出15个矿床式。勘查成果显示,热液型铀矿对岩浆岩的岩性岩相没有选择性,但与特定时期的岩浆岩有密切的关系,其中与花岗岩有关的热液型铀矿主要赋存在三叠纪花岗岩中,与火山岩有关的热液型铀矿主要赋存在早白垩世早期高钾钙碱性流纹岩-碱性粗面岩组合中,而且晚期高侵位小岩体或火山斑岩体的内、外接触带是有利的赋矿部位。 相似文献
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During the summer of 1976 waters from tributaries, rivers, springs and wells were sampled in the Walker River Basin. Snow and sediments from selected sites were also sampled. All samples were analyzed for uranium and other elements. The resulting data provide an understanding of the transport of uranium within a closed hydrologic basin as well as providing a basis for the design of geochemical reconnaissance studies for the Basin and Range Province of the Western United States.Spring and tributary data are useful in locating areas containing anomalous concentrations of uranium. However, agricultural practices obscure the presence of known uranium deposits and render impossible the detection of other known deposits.Uranium is extremely mobile in stream waters and does not appear to sorb or precipitate. Uranium has a long residence time (2500 years) in the open waters of Walker Lake; however, once it crosses the sediment-water interface, it is reduced to the U(IV) state and is lost from solution.Over the past two million years the amount of uranium transported to the terminal point of the Walker River system may have been on the order of 4 × 108kg. This suggests that closed basin termini are sites for significant uranium accumulations and are, therefore, potential sites of uranium ore deposits. 相似文献
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在华北地台北缘中新生代火山岩发育区,发现大型铀钼矿床,其外围被第四系广泛覆盖。为了进一步扩大找矿,我们采用了以遥感图象、地质图件、航磁、航放资料为基础信息的多元信息计算机综合分析技术。通过已知成矿模式的建立,对与成矿有关的地质体与基础信息源之间的相关性研究,对这些相关信息在图像处理系统中进行的组合显示分析,从而确立了各类地质体及控矿地质要素复合集聚区的多参数影像模型;查明了它们的空间分布规律;圈出了5个主体火山机构;发现了大规模蚀变带及其与铀矿化异常之间的空间相关关系。据此编制出反映该区成矿地质环境的第四系覆盖层下深部地质构造影像图及成矿远景区影像图,在某一远景区内用航空彩色红外图像及侧视雷达图像进行解译,圈定了5个隐伏次火山岩体。经钻探验证了它们的存在并发现工业铀矿化。这一切都为已知矿区的外围扩大找矿工作起了指导作用。 相似文献
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M. Th. S. Heikal B. T. El-Dosuky M. F. Ghoneim M. I. Sherif 《Arabian Journal of Geosciences》2013,6(9):3229-3239
The present study examines the natural radioactivity in basements rocks including granites and associated dikes besides stream sediments in Sharm El Sheikh area. Two main rock units are concerned; granites pertaining to Younger Granites of Precambrian age and clastic sedimentary rocks related to Miocene and Pliocene ages. This area is traversed by two shear zones that were delineated as the master fractures trending NW and NNE and controlling uranium and thorium enrichment in granites and dikes. The field and laboratory radiometric measurements revealed radiometric anomalies, in particular, along shear zones. The results of radiometric analyses including concentrations of equivalent uranium (eU), equivalent thorium (eTh), Ra, and K radionuclides as well as the calculated ratios eTh/eU and eU/Ra for representative samples belonging to all rock varieties, revealed that the felsic dikes have the highest values of the average radionuclides potential followed by the alkali feldspar granites, while the mafic dikes display the lowest radioactivity potential. On the other hand, the trends defined in the variation of uranium and thorium reflects the amount of remobilization of uranium that has occurred within the plutons. The eTh and eU/eTh ratios shows a negative correlation, suggesting that distribution of uranium and thorium was at least controlled by magmatic differentiation, while, the positive correlation between eU and eU/eTh ratios indicates enrichment of uranium through post magmatic processes. Some precautions and recommendations are proposed to avoid any possible environmental impacts from shear zone areas with high intensity of natural radiation sources. 相似文献
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Minor tin, tungsten, tantalum and beryllium mineralization occurs near Mount Isa in pegmatites along the eastern rim of the Queen Elizabeth pluton, a multi-phase pluton in the Proterozoic Sybella Granite batholith of northwest Queensland. The Queen Elizabeth pluton and adjacent metamorphic rocks were explored by Mount Isa Mines Limited during 1980–1983 to assess the tin potential of the area.An orientation study was carried out over an existing tin deposit, using stream-sediment, soil and rock-chip sampling, magnetometer and scintillometer surveys and percussion drilling. This defined the geophysical and geochemical features of the deposit, and indicated that monazite and cassiterite had related distributions and could be used as heavy-mineral tracers. Broader exploration used stream-sediment and rock-chip sampling, and airborne magnetic and gamma-ray spectrometry surveys.The eastern rim of the Queen Elizabeth pluton was found to be enriched in thorium and tin, and an area of approximately 2000 × 400 m with anomalously high tin values in bedrock was delineated in a part of the pluton not previously known to be mineralized. An economic assessment led to relinquishment of the area at that stage. Although no new areas of economic mineralization were found, the study indicated that in this region the thorium gamma-ray response can be used in regional airborne surveys to define areas of prime interest for tin exploration, and that monazite in stream sediments can be used as a heavy-mineral tracer for pegmatitic tin mineralization. 相似文献
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国家铀资源评价(NURE)计划实现了覆盖美国本土和阿拉斯加的1∶250000 NTMS图幅航空γ能谱测量和航磁测量,通过简要回顾该计划历程,重点针对NURE中航空地球物理勘查(航空γ能谱和航磁测量),讨论了航空地球物理勘查中测量技术、数据处理及解释方法等。NURE航空测量在铀矿勘查和辐射环境评价、洲际航空地球物理编图等领域发挥了巨大作用,产生了意义深远的影响。在总结NURE航空测量经验和做法的基础上,针对我国航空γ能谱测量勘查现状,建议从国家层面进行顶层设计,尽快实施我国陆域范围内的航空γ能谱和航磁框架性测量,实现对我国陆域航空γ能谱测量全覆盖,建设具有中国特色的航空γ能谱测量与监测体系。 相似文献
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我国铀矿床主要划分为四大类型,包括花岗岩型铀矿床、火山岩型铀矿床、砂岩型铀矿床和碳硅泥岩型铀矿床。花岗岩型铀矿约占我国已探明铀矿总资源储量的三分之一以上,是我国重要的铀矿化类型。地球化学勘探方法对花岗岩型铀矿床勘查具有良好的效果。根据全国铀矿资源潜力评价项目研究成果,在大量研究中国花岗岩型铀矿化水系沉积物地球化学异常特征基础上,总结了一套对花岗岩型铀矿化勘查稳定的、行之有效的指示元素及其组合,确定了花岗岩型铀矿化地球化学异常模式,并以实例说明典型花岗岩型铀矿化异常模式。水柰沉积物地球化学异常是进行铀矿产预测评价的有效手段,对铀矿资源的潜力评价发挥了重要作用。 相似文献
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In the absence of historic geochemical baseline data for the Grants uranium region, environmental changes resulting from uranium
mine-mill activities can be determined only by indirect methods. A methodology for determining the age of recent sediments
in streams draining the region has been established based on combined geomorphic, stratigraphic, and radiometric dating techniques.
Because clayrich sediments retain possible radionuclides and heavy metals derived from mineralization and mined sources, sample
sites which contain fine-grained deposits that both predate and postdate mine-mill activity were located in abandoned-channel
segments (oxbows) of major streams draining the eastern Grants uranium region. Aerial photographs (and derivative maps) taken
between 1935 and 1971 provided the historical and geomorphic documentation of approximate dates of oxbow formation and ages
of alluvial fills in the abandoned-channel segments. Pits were dug at these oxbow sites to determine stratigraphy and composition
of the deposits. Samples collected from pit walls and auger holes below the pits were subjected to radiometric analysis by
gamma ray spectrometry for the artificial radionuclide Cs-137 and the natural radionuclide Pb-210 as well as other U-238 and
Th-232 daughters. Because of the dynamic nature of the system, absolute dating with Cs-137 was not possible but samples could
be dated as either pre-or post-1950. The 1950 date is important because it marked the beginning of the uranium exploitation
in the region. The Pb-210 dating was not possible because background Pb-210 was very high relative to fallout Pb-210. 相似文献
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A reconnaissance exploration survey over 14 000 km2 of Precambrian terrain in South Greenland using stream-sediment and stream-water samples delineated a central uranium district of 2000 km2 with enhanced uranium levels and smaller anomalous zones in the south of the field area.The area is underlain by Archean and Proterozoic gneisses, granites and metasediments all of which have been intruded by late Proterozoic alkaline intrusions (Gardar Province). The terrain is mountainous and the streams are either steep torrents or impeded drainages typical of glaciated terrains with boggy organic rich sediments.The central uranium district was defined by a high uranium background in both stream sediments (5–20 ppm) and stream waters (0.5–1.0 ppb) and a markedly higher frequency of very anomalous values in the order of 50–100's ppm in the stream sediments and 1–10 ppb in the stream waters. An areal correlation of uranium, in this district, with high pH and conductivity in the stream water in addition to a higher organic content noted in the stream sediment raised the question of a possible enhancement of uranium values due to secondary environmental effects. On the other hand, an areal correlation of uranium with niobium and other trace elements characteristically associated with alkaline rocks, and the geographic proximity of this uraniferous district to the alkaline intrusions suggested a genetic relationship between uranium mineralization and the alkaline igneous activity.Limited follow-up work located 8 pitchblende occurrences in this extensive district. The pitchblende is in veins which contain quartz, calcite, iron oxide, fluorite and minor sulphides. The isotopic (U-Pb) age of the pitchblende, which ranges from 1180-1090 Ma, corresponds to the late stages of Gardar alkaline igneous activity. It is concluded, therefore, that the reconnaissance geochemistry reflects a district-wide hydrothermal event related to the late volatile differentiates derived from the highly fractionated alkaline magma. A combination of primary and secondary features have complemented each other in enhancing the geochemical reconnaissance data and emphasized its importance but has not materially altered the interpretation.The south of the field area also has a relatively high uranium background in both the sample media with some discrete anomalous zones, usually with a slightly lower order of magnitude than the central area, but still with a distinct contrast of 5–10 times. Fine-grained uraninite has been found in the area occurring as disseminated grains in pegmatitic elements as in the central district. Isotopic ratios (U-Pb) suggest an age of 1728 ± 30 Ma which probably reflects the long cooling of the granite.It is concluded that the geochemical reconnaissance data delineated two uranium metallogenic districts characterized by distinctly different types of uranium mineralization. It is suggested that South Greenland may be part of a much wider uranium geochemical province which includes parts of Labrador. To the present plate-tectonic models, which suggest such a connection (Le Pichon et al., 1977), must be added the comparable reconnaissance geochemical results (G.S.C. Open Files nos. 748 and 749), and the similar 1730 Ma age of the Kitts uranium mineral occurrence in Labrador (Gandhi, S.S , 1978) to that of the uraninite found in the south of the field area in Greenland. 相似文献
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一种有用的解释参数——航空伽玛能谱变异系数 总被引:1,自引:1,他引:1
本文讨论了航空伽玛能谱变异系数(包括总计数率及钾、铀、钍含量变异系数, 简称伽玛能谱变异系数)的计算、变异系数图的编制方法以及它们的地质应用。伽玛能谱变异系数是一种反映放射性元素空间分布特点及其地球化学活动程度的参数。变异系数图具有信息丰富、用途较广泛的特点。结合其它物化探资料, 可用来进行地质填图和找矿远景评价等。研究表明, 伽玛能谱变异系数可做为航空伽玛能谱资料解释一种很有用的参数。 相似文献