Specific features in distribution of natural radioactivity in rocks of the Bazhenovo Formation on the western slope of the Surgut Dome,West Siberia

This paper presents an analysis of the radioactivity distribution in the Bazhenovo Formation rocks on the western slope of the Surgut Dome. The maximum uranium concentrations are confined to accumulations of organic matter and are proportional to its concentration in the rocks. The lowermost part of the section has lower radioactivity values than the upper one. The value of radioactivity varies throughout the area of the Surgut Dome. Coeval analogs of the Bazhenovo Formation show lower radioactivity values.     

Radiostratigraphic study of the deposits of the Maikop Group, Western Azerbaijan

This work presents the results of biostratigraphic study of natural outcrops of the Maikop Group, which were first carried together with detailed radiometric studies in the Ganja oil and gas-bearing region, Western Azerbaijan. The paleontological research method included determination of the genus or species (depending on the preservation) of microfaunistic remains (foraminifera, ostracods, fish remains). The radiometric research method included measurements of the integral radioactivity in the field, the sampling, as well as laboratory radionuclide (spectral) analysis. As a result of our research, the stratigraphic control of variation in the radioactivity of rocks of the Maikop Group of the Ganja oil and gas-bearing region has been established. The radioactivity of Oligocene rocks is predominantly determined by potassium content. The radioactivity of the Miocene part of the section of the Maikop Group is determined by uranium-potassium contents. Within the Ganja oil and gas-bearing region, deposits of the Kotsakhurian regional stage, which are usually referred to ??barren?? formations or anoxic ??fish facies??, contain a significant number of species of benthic foraminiferal fauna.     

我国西南地区铀矿地质实验室退役工程环境评价

我国西南地区现有7个铀矿地质实验室，历年集有大量可能对环境产生污染的样品。本文在对铀矿地质实验室现状进行调查的基础上，介绍了铀矿地质实验室的退役治理方法，并对退役治理后的环境进行了环境放射性水平评价。结果表明，所有污染及危害因素被全部清除，恢复了环境质量。     

Assessment of clay content from the analysis of K,U, and Th distribution in different grain-size fractions of the productive sediments of the Lovin Field,Western Siberia

During the calculation of the oil and gas resources of Western Siberia, especially in the sediments of the Tyumen Formation, the presence of thin nonreservoir clay intercalations must be accounted for. However, the resolution of standard geophysical methods that are used to identify productive sequences is insufficient, and the clay intercalations are included into the total thickness of reservoir rocks, which leads to considerable errors during resource assessment. The most efficient method for the estimation of clay mineral content in sedimentary rocks is the gamma method or gamma-ray well logging, which is typically used for this purpose. However, its application requires the knowledge of correlations between the abundance of clay minerals in the sediments; the contents of K, U, and Th; and total radioactivity. To solve this problem, four grain-size fractions (sand, coarse silt, fine silt, and clay) were separated from the sediments of the Tyumen Formation at the Lovin Field and were analyzed for naturally radioactive elements (NRE), total radioactivity, and mineral composition. The tendencies found in the distribution of NRE and total radioactivity in different grain-size fractions provided a methodical basis for the determination of clay mineral contents in the productive sediments of the Tyumen Formation at the Lovin Field using gamma-spectrometric data.     

Geochronology of a surface core in the northern basin of Lake Qinghai： Evidence from ^210pb and ^137Cs radionuclides

1 Introduction The radionuclides 210Pb and 137Cs are of particularimportance for estimating the dates of recentsediments. It was Goldberg (1963) who firstlysuggested that the disequilibrium between 210Pb and226Ra could serve as a geochronometer applicable…     

Paleoproterozoic quartz-pebble conglomerate type uranium mineralisation in Mankarhachua area,Angul district,Orissa

Ground Radiometric survey of Paleoproterozoic pyritiferous quartz-pebble conglomerate (QPC) occurring to the north of Pallahara area led to the discovery of a QPC type uranium mineralisation near Mankarhachua village. Significant radioactivity is recorded in three sub-parallel uraniferous QPC horizons with metamorphosed pebbly to medium grained recrystallised massive sandstones. Detrital grains of uranothorite, thorite, radioactive allanite, monazite, zircon, minute uraninite grains in carbonaceous matter and thucolite contributes to the radioactive phases present in QPC matrix. Adsorbed U on limonite and goethite, secondary uranyl minerals in matrix, along bedding planes and fractures are commonly observed. This discovery has opened up a new horizon for future exploration for QPC type uranium mineralization in the area. The paper presents observations on geology, radioactivity, petrological and geochemical nature of the uraniferous QPC horizons.     

Natural radioactivity in basement rocks and stream sediments, Sharm El Sheikh Area, South Sinai, Egypt: radiometric levels and their significant contributions

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.     

Modelling seasonal variations of natural radioactivity in soils: A case study in southern Italy

The activity of natural radionuclides in soil has become an environmental concern for local public and national authorities because of the harmful effects of radiation exposure on human health. In this context, modelling and mapping the activity of natural radionuclides in soil is an important research topic. The study was aimed to model, in a spatial sense, the soil radioactivity in an urban and peri-urban soils area in southern Italy to analyse the seasonal influence on soil radioactivity. Measures of gamma radiation naturally emitted through the decay of radioactive isotopes (potassium, uranium and thorium) were analysed using a geostatistical approach to map the spatial distribution of soil radioactivity. The activity of three radionuclides was measured at 181 locations using a high-resolution ?-ray spectrometry. To take into account the influence of season, the measurements were carried out in summer and in winter. Activity data were analysed by using a geostatistical approach and zones of relatively high or low radioactivity were delineated. Among the main processes which influence natural radioactivity such as geology, geochemical, pedological, and ecological processes, results of this study showed a prominent control of radio-emission measurements by seasonal changes. Low natural radioactivity levels were measured in December associated with winter weather and moist soil conditions (due to high rainfall and low temperature), and higher activity values in July, when the soil was dry and no precipitations occurred.     

In-ground environmental radioactivity monitoring in the Culpeper Basin,Virginia, using LiF thermoluminescence dosimeters

A new environmental in-ground radioactivity monitoring technique using LiF thermoluminescence dosimeters was tested in the Culpeper Basin, Northern Virginia. The dosimeters were buried at a depth of 0.45 m (∼ 18 in.) for approximately four months. There was a significant positive correlation (at the 99.9% confidence level) between the total accumulated radioactivity signal from the dosimeters and the on-site 100 second gamma-ray spectrometer measurements. The minimum-maximum dose rate from the buried thermoluminescence dosimeter measurements was 0.06 to 1.08 mR per day (or 2.5 to 44.5μR per hour). There are two factors which permit better background levels of radioactivity to be established by thermoluminescence dosimeters compared with other methods for environmental monitoring programs. First is the great sensitivity of thermoluminescence dosimeters in terms of minimum dose rate that can be registered (mR per month orμR per hour). Second is the fact that accumulation of radioactivity signal over a long period of time tends to eliminate short-term environmental changes that affect measurements with gamma-ray spectrometers and scintillation counters.     

Geochemical baselines for the radioelements K,U, and Th in the Campania region,Italy: a comparison of stream-sediment geochemistry and gamma-ray surveys

This paper presents new data on the baseline concentrations of U, Th and K in 2389 stream sediments over the whole Campania region. These data, based on systematic sampling and analysis, are compared with those obtained by gamma-ray spectrometry surveys.Variations in the U, Th and K concentration in the surficial environment of the Campania region appear to be related to bedrock lithology. Generally, high U, Th and K values in stream sediments correspond well with the occurrence of volcanic rocks in the central-western part of the region, whereas low values are found in areas characterized by silico-clastic and carbonate deposits, occurring mostly in the southern and eastern part of the region. Gamma-ray spectrometry maps show a similar pattern, although the distribution of the highest radioactivity levels define more restricted areas than the ones resulting from mapping stream sediment geochemistry. Particularly high ⁴⁰K radioactivity levels delimit all the known eruptive centers (Roccamonfina, Campi Flegrei and Somma–Vesuvius), including the fissural sources of Campania Ignimbrites, much better than U and Th radioactivity. One of the concerns for human health in the Campania region is the total gamma radiation and Rn potential related mostly to alkaline volcanics of the Neapolitan volcanological province. In particular, geothermal activity occurring in all the Campanian volcanic areas represents a potential hazard for Rn gas.     

Application of geochemistry and radioactivity in the hydrogeological investigation of carbonate aquifers (Sierras Blanca and Mijas,southern Spain)

The chemical characteristics, ³H contents and radioactivity of groundwaters from the Sierras Blanca and Mijas (Southern Spain) have been studied in relation to the chemical composition and radioactivity of the aquifer host rocks, and the residence time of the water. The Sierras Blanca and Mijas are made up of calcitic and dolomitic marbles of Triassic age. The groundwaters that drain the calcitic marbles (which outcrop principally in the western Sierra Blanca) have less mineralization, which descreases quickly with recharge (as does the ³H content), and the gross alpha and beta activities are below detection limit. This is due to the short residence time of water inside the aquifers which are conduit flow systems. The waters of the dolomitic marbles (eastern Sierra Blanca and Sierra Mijas) have higher and less variable mineralization and contain greater concentrations of Mg²⁺, SiO₂ and SO²⁻₄ (ions normally associated with slow flows). The ³H contents are more uniform with time (indicating an older age) and there is detectable natural radioactivity, because the waters have a longer residence time in the aquifers, which are diffuse flow systems.     

Geochemistry,petrogenesis and radioactive mineralization of two coeval Neoproterozoic post-collisional calc-alkaline and alkaline granitoid suites from Sinai,Arabian Nubian Shield

The Younger Granites of Yahmid-Um Adawi area, located in the southeastern part of Sinai Peninsula, comprise two coeval Late Neoproterozoic post-collisional alkaline (hypersolvous alkali-feldspar granites; 608–580?Ma) and calc-alkaline (transsolvous monzo- and syenogranites; 635–590?Ma) suites. The calc-alkaline suite granitoids are magnesian and peraluminous to metaluminous, whereas the alkaline ones are magnesian to ferroan alkaline to slightly metaluminous. Both granitoid suites exhibit many of the typical geochemical features of A-type granites such as enrichment in Nb (>20?ppm), Zr (>250?ppm), Zn (>100?ppm) and Ce (>100?ppm) and high 10000*Ga/Al₂O₃ ratios (>2.6) and Zr?+?Nb?+?Y?+?Ce (>350?ppm). Accessory mineral saturation thermometers demonstrated former crystallization of apatite at high temperatures prior to zircon and monazite separation from the magma for both granitoid suites. The mild zircon saturation temperatures of the studied Younger Granites (around 800?°C) imply low-temperature crustal fusion and incomplete melting of the largely refractory zircon. The two Younger Granite suites were semi-synchronously evolved during the post-collisional stage of the Arabian-Nubian Shield subsequent to the collision between the juvenile shield crust and the older pre-Neoproterozoic continental blocks of west Gondwana. Their parental magmas has been generated by melting of crustal source rocks with minor involvement from mantle, which might participated chiefly as a source of heat necessary for fusion of the crustal precursor. Extensive in-situ gamma-ray spectrometry revealed anomalously high radioactivity of some Younger Granite exposures along Wadi Um Adawi (eU; 388–746?ppm and eTh; 1857–2527?ppm) and pegmatitic pockets pertaining to the calc-alkaline suite (equivalent U and Th; 212–252?ppm and 750–1757?ppm, respectively). The radioactivity of the syngenetic pegmatites arises from the primary radioactive minerals uranothorite and thorite together with the U- and/or Th-bearing minerals zircon, columbite, samarskite and monazite. The anomalously high radioactivity of some Younger Granite exposures in Wadi Um Adawi stem from their appreciable enclosure of the epigenetic uranium minerals metatorbenite and uranophane.     

内蒙古四子王旗芒和特铀矿地质特征

在铀矿航空γ能谱测量和地面放射性普查工作的基础上,通过对铀矿异常进行地表揭露和钻探工程验证,发现了芒和特铀矿床。铀矿床类型为湖沼相砂岩型沉积矿床,含铀矿岩石为古近系粉砂岩,铀矿化具有放射性强度较弱、铀含量较高和矿化分布不均匀的特点。深入分析铀矿放射性强度弱的原因,采用放射性测量结合化学样品分析的方法,能够提高找矿效率。     

Petrology, geochemistry and uranium mineralisation of post-collisional magmatism around Goanikontes, southern Central Zone, Damaran Orogen, Namibia

The Goanikontes area lies within the southern Central Zone of the northeast trending branch of the Damara Orogen. The cover succession around Goanikontes, which comprises Etusis to Chuos Formation metasediments, is in tectonic contact with older pre-Damaran basement rocks. The area can be divided into three structural domains with basement in the east, a northeast-plunging anticline of Damaran metasediments to the west and a high strain zone up to 1 km wide that separates them and truncates the anticline. The high strain zone has provided an important focus for the emplacement of sheeted granites adjacent to the basement-cover contact. Goanikontes is also one of several significant uranium anomalies within the Damaran Orogen, and the excellent 3D exposure of the Swakop river has provided evidence for an interpretation of the tectono-metamorphic setting of magmatism and mineralisation. The granitoids have been divided into equigranular granites and sheeted leucogranites. The sequence of emplacement of the equigranular granites is from red syenogranite (534±7 Ma) to later grey monzogranite (517±7 Ma) with foliated basement-hosted granite of probable time equivalence to the syenogranites. Each type can be distinguished on major- and trace-element geochemistry. The later sheeted leucogranites, which are volumetrically the most important, intrude both basement and cover rocks. These have been divided into six distinct types based on field characteristics and structural setting backed by geochemical data and fluid extraction analyses. The earliest type A are irregular in form, boudinaged and folded by D₃, and geochemically distinct with notably low HFSE; type B's are white, weakly foliated, folded by D₃, garnetiferous and highly peraluminous; type C are tourmaline-bearing, occasionally boudinaged and exhibit the typical sheet-form within the cover rocks. Of the post-D₃ sheets, type D, which is restricted to the high strain zone is characterised by smoky quartz, high radioactivity and often by visible betafite or beta-uranophane; type E, the dominant type within the high strain zone contains prominent oxidation haloes and type F is red in colour, coarsely pegmatitic and has the highest concentration of alkalis. The uranium-mineralised type D sheets have consistently higher fluid and CO₂ content than other sheeted leucogranites. The close correlation between sheet type and uranium abundance, supported by linear trends on LIL plots suggests that the distribution of radiogenic elements is primarily magmatic with more recent meteoric re-distribution, rather than due to substantial hydrothermal modification     

松辽盆地大庆长垣四方台组可地浸砂岩铀成矿测井评价

为了研究孔隙度、渗透率、泥质等参数与砂岩型铀矿成矿的关系,本文对松辽盆地中央坳陷大庆长垣南部某区块四方台组底部砂岩进行分析。含铀矿砂岩具有高放射性,这使得测井曲线的密度值异常降低,自然伽马值异常升高。通过研究总结出利用升高的自然伽马曲线校正密度曲线的方法,以及利用其他不受放射性影响曲线重构自然伽马曲线的方法。与岩心的对比分析结果证明,校正后的密度曲线与重构后的自然伽马曲线较准确,密度曲线校正与自然伽马曲线重构解决了含铀砂岩利用测井曲线求取孔隙度、渗透率参数不准的问题。在准确求取测井参数的基础上,得到能展现砂体内部非均质性特点的物性空间展布并成图分析,进而得出本地区有利于铀成矿的物性条件：产生铀矿的砂体并不是孔渗性质最好的地方,也不是孔渗性质最差的地方,而是处于由高孔渗向低孔渗过渡的地方。     

A study of gross alpha and beta measurements for thermal springs in Central Anatolia,Turkey

A screening of natural radioactivity content has been carried out in thermal water samples collected from surrounding of Central Anatolia, Turkey. The concentration levels of gross alpha and beta of 19 different samples has been determined using the low background gas-flow proportional counter. The measured gross alpha and beta activities in waters range from 0.11 to 16 Bq/L and 0.10 to 16.9 Bq/L, respectively. The measured values of gross alpha and beta concentrations are compared to previous studies in the literature and recommend WHO guideline activity concentration. The data resulting from the measurement have been statistically analyzed.     

Radioelement Mapping and Environmental Monitoring of Surface Deposits using Ground Gamma Ray Spectrometry of the Area Adjacent to El‐Ramlah Village,Southwestern Sinai,Egypt

A ground‐based gamma‐ray survey has been performed in the area close to El‐Ramlah village, southwestern Sinai, Egypt, using a GS‐512 spectrometer. The main objective of this survey was to delineate radioactive anomalies within the surface of the study area and to identify the environmental effects of natural radioelements on the new inhabitants, Bedouins, who live in the recently built village in this region of the Sinai Peninsula. The results show that the maximum radioactivity of the total count component (T.C.) was about 15.7Ur at the northern part of the study area. The average radioelements concentration were 0.4% for potassium, 1.6 ppm for equivalent uranium and 4.5 ppm for equivalent thorium. To identify and map the environmental effects of the concentration of these radioelements on El‐Ramlah village, measurements of potassium (K%), equivalent uranium (eU) and equivalent thorium (eTh) were converted into an equivalent dose rate. The results illustrate that, the levels of effective dose rate of the natural radioactivity of the area of study remains in the safe range without any harm to living organisms, and it stays within the maximum permissible radiation dose rate (1.0 mSv y^?1) recommended by the International Commission of Radiological Protection.     

Basic Structural and Geological Features of the Stolovac Uranium Mineral Occurrence, Eastern Serbia

The uranium mineral occurrence of Stolovac is located in the middle of a Permian red sandstone formation, the westernmost east‐Serbian Carpatho‐Balkan metallogenic province, or the Ridanj–Krepoljin ore zone. It was found by geological radiometry survey at the anomaly spots indicated by aerial gamma‐ray spectrometry (AGS). The task of anomaly identification is to accurately locate the AGS‐recorded anomalies in the field, to define the source of anomalous radioactivity (natural or artificial), to understand the relationship between the anomalous radioactivity and the given structural and geological situation, and to sample the material. The geological radiometry survey at scale 1:25,000 indicated increased radioactivity in gray sandstones of the Stolova?ki stream bed in Stolovac, some 40 km NE of Para?in. The instrument used was a scintillometer SSP 2NF, and the measured radioactivity was 10‐fold higher than the local background level. Of all the customary field work, the greatest volume (trenching, drilling and accessory testing) was carried out in Stolovac; other radioactivity anomalies in the red sandstone formation remained inadequately explored and are the subject of this paper. The 3‐year exploration in uranium at Stolovac indicated sandstone‐type infiltrated uranium mineralization in sandstones in the middle of the Permian red sandstone formation: a complex called “variegated rocks”.     

An investigation about natural radioactivity,hydrochemistry, and metal pollution in groundwater from Calabrian selected areas,southern Italy

The increasing interest in radioactivity has brought about the need for an assessment of human exposure to radiation. It is, therefore, necessary to examine naturally occurring radioactivity in the environment, especially its occurrence in groundwater. The aim of this work was then to study the levels and behavior of the most significant natural radionuclides, also in order to improve the knowledge of the hydrochemical processes involved in the selected groundwater systems. Natural radioactivity in fifteen Calabrian groundwaters for human use was investigated through high-resolution gamma spectrometry (with a negative-biased Ortec HPGe detector) and liquid scintillation measurements. Particular attention was given on those radionuclides (³H, ²³⁸U, ²²⁶Ra, and ²²⁸Ra), which contribute in a significant way to the overall effective dose received by members of the public due to the intake of drinking water originating from groundwater systems. The activity concentration of ²³⁸U varied from 1 to 51 mBq/L, as a result of the geology of the investigated area and of the oxidizing conditions that favored U dissolution. ²²⁶Ra presented a broad range of activity concentrations (0.011–0.14 mBq/L), lower than uranium ones because radium occurs in groundwater under reducing conditions. Some heavy metals (Cd, Pb, Be, Hg, Ag, As, Tl, Sb, Se, and Ni) were also investigated through ICP-MS measurements and compared with the limits set by the Italian Legislation. Metals are released into the environment by both natural and anthropogenic sources; they leach into underground waters, moving along water pathways and eventually depositing in the aquifer.     

Detailed ground radiometric surveys on Gabal El Sela,Southeastern Desert,Egypt

Gabal El Sela area lies in the extreme southeastern part of the eastern desert in Egypt. It is covered by basement rocks of different compositions. The detailed work in this area covers about 4 km² and it is represented mainly by coarse younger granite as a curved shape extended in NE–SW direction and dissected by many faults in various trends; some of them are invaded by dykes especially the lamprophyre dykes in the ENE–WSW trend. Detailed geological, structural, and radiometric investigations are carried out on the area. The radiometric data are statistically analyzed and the results show that the total count radiometric map reflects six separate anomalies. The field work revealed that four anomalies are related to lamprophyre dykes, the other two anomalies are structurally controlled by NE–SW and E–W faults. These anomalies are followed by some trenches which traced and measured in detail exhibiting the possible extension of these anomalies with depth. These measurements show that lamprophyre dyke has the highest reading of radioactivity, it reaches 270 Ur in the surface and to 6,300 in the trenches. While the granite of the sela area is considered possesses high level of radioactivity, where its radioactivity ranges from 19.9 to 81 Ur with an average of about 32 Ur.