Gamma Ray Spectrometric Survey Research Articles

Age and structure of the Permian Brook Street Terrane, Takitimu Mountains, New Zealand

ABSTRACT We use a recently completed airborne magnetic and gamma-ray spectrometric survey, and new U/Pb and 40Ar/39Ar age determinations, to revise and clarify several aspects of Brook Street Terrane geology in the Takitimu Mountains. Steeply dipping and homoclinal Permian Takitimu Subgroup formations defined in the central part of the range can, with moderate confidence, be traced along strike to other parts of the range where they are more complexly folded and faulted. We report intrusion ages for three Brook Street plutonic suites: pyroxene-bearing White Hill Intrusives (306-270 Ma, U/Pb zircon), amphibole-bearing Mackinnon Peak Intrusives (261 ± 1 Ma, 40Ar/39Ar amphibole), and shoshonitic Wether Hill Dikes (254 ± 1 Ma, 40Ar/39Ar plagioclase). Geological relationships between these intrusions and the host Takitimu Subgroup reinforce the Early Permian age of the latter, which is distinct from the overlying Late Permian Productus Creek Group. The Wether Hill Dikes mark the cessation of igneous activity in the Brook Street Terrane at c. 254 Ma. A large (n = 499) dataset of detrital zircon U/Pb ages from the nonmarine Jurassic Barretts Formation confirms a local Median Batholith-Tuhua Intrusives provenance and supports a post-Permian fore-arc tectonic setting along the Gondwana margin.

Aerial gamma-ray spectrometric survey data as a guide for probable hydrocarbon accumulations at Abu-Zeneima/Al-Tur area, Southwestern Sinai, Egypt

A method using surface and aerial gamma-ray spectral measurements to explore the hydrocarbon accumulations in Abu-Zeneima/Al-Tur area of Southwestern Sinai, Egypt, was selected due to both its structural setting and its location in close proximity to the Gulf of Suez, which represents one of the important sites of oil production in Egypt.Examination of the normalized potassium map (KD %) shows low concentrations above Abu-Alaqah, Thebes, and Kariem formations, while normalized equivalent uranium map (eUD %) shows a high concentration above these formations. The Deviation of Radio-Active Derivative (DRAD) map shows some of the delineated high positive DRAD anomalies, which are elongated in the NW–SE direction and related to Abu-Alaqah, Thebes, and Kariem formations.Data from every formation and rock unit as well as each flight line were extracted in XYZ format and evaluated with simple statistical applications. The DRAD arithmetic means plus three standard deviations (x + 3s) and plus two standard deviations (x + 2s) for the data set all over the study area were computed and reached the values of 2.5 and 2.1, respectively. Any single point that possesses a value greater than these two values should have a probability of 99.7% and 95%, respectively, of possible petroleum accumulations and represents a sure anomaly. The use of these criteria helped identify Abu-Alaqah, Thebes, and Kariem formations. Moreover, five zones along four flight lines correlating geologically with Abu-Alaqah, Thebes, and Kariem formations have sure anomalies. This might indicate a prospective possibility of feasible subsurface petroleum accumulations in Abu-Zeneima/Al-Tur area, Southwestern Sinai, Egypt.

El Ramsa area, Southwestern Sinai, Egypt: radioactivity, mineralogy, and geochemistry studies

Um Bogma Formation represents the main target for uranium exploration at El Ramsa area. The gamma-ray spectrometric survey shows diverse measurements of radioactivity over the surveyed area, which reflects contrasting radioelement, contents for the exposed various rock types. The highest radio-spectrometric levels are located in the northeast part and scattered parts to the southwest of the study area. They are mainly associated with Um Bogma Formation. Seven uranium anomalous localities are recorded which can be used as exploration guides to explore further uranium anomalies. The highest radiometric uranium anomalies were recorded within gibbsite, carbonaceous shale, dolomite, marl, and ferruginous sandstone of Um Bogma Formation. The chemical investigations indicate enrichment in U, Cu, Mn, Cd, Ni, Zn, and Pb elements. It also reveals high uranium contents up to 640 ppm and a strong positive relation between uranium and both iron and aluminum oxides was noticed. Furthermore, high content of rare earth elements, reaching up to 5736 ppm with an average 4204 ppm, is reported in gibbsite samples. Uranium minerals such as vanuralite, sklowdowskite, and phosphuranulite were detected. The present study reveals that the source of uranium and other elements in El Ramsa area is the hydrothermal fluids which associated with the magmatic eruption during the Paleozoic events.

Radiological environmental studies of Al Aziziah area and vicinity, Al Madinah Al Monawarah, Saudi Arabia.

The Al Aziziah area is built on volcanic and granitic rocks. The igneous rocks always contain a high amount of naturally radioactive elements such as uranium, thorium and potassium, which produce gamma rays causing environmental hazards when exceeding the permissible limit. Radon gas is a result from the decomposition of uranium/thorium leaks into enclosed areas (e.g. homes or offices). This leakage is controlled by many conditions, and one of them is the underlining rock type. To work on such an environmental study, a gamma ray spectrometer survey was used. The uranium, thorium and potassium contents, as well as their ratios and the total radiation, were determined and mapped. The radiation dose rate was calculated and mapped in mSv/y and nGy/h units. The radiation contamination of groundwater is detected from the contour map of the dose rate over the artificial drainage lines of rains and floods which move this water to the groundwater wells. The main results are as follows: granitic rocks show an average dose rate of about 2.4mSv/y, while the deposits of these rocks have an average dose rate of 1.2mSv/y. A low average dose is recorded over the basalt. The average radiation dose recorded in the study area is 1.08mSv/y, while its range is from 0.001 to 4.41mSv/y. The estimated effective doses within the Al Aziziah area and vicinity area were higher than 1mSv/y, which is the public exposure limit, and lower than the occupational exposure limit of 20mSv/y. We recommend ventilating homes and offices in these places on an ongoing basis and constant radon measuring in closed places.

Black sand deposits; their spatial distribution and hazards along the northern coast of Sinai Peninsula, Egypt

Airborne Gamma Ray Spectrometric (AGRS) surveys and image processing techniques are utilized to define the occurrence of black sand deposits along Sinai's northern coastal plain. High contents of radioactive minerals are detected in these deposits; zones of high concentrations of uranium 238U, thorium 232Th, and potassium 40K could be outlined. Remote sensing and GIS techniques are integrated to study the pattern of coastline changes and its relationship to the distribution of black sand deposits during the period between 2000 and 2020. The results reveal high 232Th anomalies along El-Arish Beach due to its high monazite content; containing 7.92% ThO2. In addition, high uranium anomalies on the eastern sides of El-Bardawil Lake result from the abundance of zircon in the sediments surrounding the lake, which contain 5.29% U3O8. Areas of high radiation levels, which exceed the allowed limits for human exposure, are outlined by calculating adsorbed and annual effective dose rates. Unfortunately, many of these areas are open and easily accessible to the public, presenting a direct threat to the health of local inhabitants. These anomalous areas ought to be excluded from the ongoing national housing and land reclamation projects, where long-term exposure to high gamma radiation increases the cancer risk factor in humans.

Mineralogy and ground gamma-ray spectrometric investigation for phosphates of Gabal Abu Had area, Central Eastern Desert, Egypt

ABSTRACT The present study deals with geologic and mineralogic studies as well as gamma-ray spectrometric survey for uranium potential phosphates of Duwi Formation and environmental assessment at Gabal Abu Had environ. These phosphate deposits are considered as an important potential resource for uranium and rare earth elements as by-products. The study area lies to the NE of Qena town and dissected by Qena – Safaga asphaltic road. The Duwi Formation in the study area conformably overlies Qusseir Formation and underlies Dakhla Formation; this succession is capped with Esna and Thebes Formations and eroded along wadis which are filled with Quaternary deposits. Phosphate deposits (Duwi Formation) of Abu Had area are enriched with uranium, which may be extracted as a by-product of making fertilisers. Petrographic studies indicate that phosphate beds are composed of phosphatic particles which include collophane grains, bioclasts (bone and teeth fragments), as well as, non-phosphatic particles which include quartz, calcite and pyrite embedded in silica, calcite or iron oxides cement. XRD results showed that hydroxylapatite is the principal phosphate mineral, and the non-phosphate minerals include calcite, quartz, gypsum and anhydrite. Ground gamma-ray spectrometric results indicated that the study area has K values range from 0.2% to 4.4%, eTh values range from 0.5 to 18 ppm and eU values range from 0.5 to 100 ppm. The phosphate-bearing beds of Duwi Formation have the highest values of eU reach up to 100 ppm. The uranium anomalies mostly elongated in NW-SE trend that related to the NW-SE strike-slip faults of the area. The average value of annual effective dose rates of phosphates at Abu Had area equals 0.32 mSv/y which, less than the worldwide permissible level of annual effective dose rate (1 mSv/y).

SEPARATING THE ANOMALOUS ZONES OF GAMMA-RAY SPECTROMETRIC DATA USING THE MEDIAN TO FIT THE MATHEMATICAL SURFACE ON EL-MISSIKKAT EL-GIDAMI AREA, CENTRAL EASTERN DESERT, EGYPT

Traditionally, the least-squares method is applied to separate the highly radioactive zones of gamma-rayspectrometric maps in order to find the normal radioactive background of the host rocks. In the presentstudy, the regional background of gamma-ray spectrometric data was calculated by using the medianinstead of least-squares method which is based on the mean. The obtained least-squares do not properly fitdue to the strong effect of the few outlier data points that are extremely high or low. The median is lessaffected by outliers and skewed data. If we reject these anomalous zones data, the proper fitting takes place.This study deals with using the median as a more suitable measure of central tendency for data classified onan ordinal scale. The mean is not suitable when the data include exceptionally high or low values becausethese have great influence on the outcome. The median was applied to the gamma-ray spectrometric (TotalCount) survey data of El-Missikkat-Gidami area to separate the radioactive anomalous zones from thenormal radiation of the host rocks.

Geographical Features of Pollution of the Territory of Yakutia With Cesium-137

A study is made of the present-day levels of global 137Cs deposition in permafrost soils of the tundra and taiga zones of Yakutia. It is shown that the reserves of 137Cs in the soils of Yakutia vary over a significant range according to the landscape and climatic features of the territory. The largest amount of 137Cs is contained in soils of the mountain areas (Aldan Highlands and Ulakhan-Chistai Range) located in the zone with maximum average annual precipitation amount, and the smallest amount occurs in the soils of the tundra zone. It is found that the average density of soil pollution by 137Cs in the flat study areas of the territory of Yakutia has now decreased by a factor of 3 to 4 in general when compared with data of airborne gamma-ray spectrometric surveys conducted during 1968–1974 on the territory of the Yakut ASSR, due to its radioactive decay, burial, removal from the surface waters and accumulation by vegetation. It is shown that in the surveyed areas of the plains and mountains of Yakutia, the global deposition of 137Cs in soils is, on average, by a factor of 2–4 less than in the soils of Ural, Western and Southern Siberia and other territories of Russia. A correlation between the density of soil pollution by 137Cs and the atmospheric precipitation amount was revealed. The main regularities of 137Cs migration and redistribution were established in different types of soils of the areas of cryogenic landscapes associated by the runoff. In the harsh climatic conditions of Yakutia, vertical and lateral migration of 137Cs is weaker in frozen soils than in soils of the European part of Russia contaminated by radioactive cesium after the accident at the Chernobyl nuclear power plant.

Radioactive anomalies associated with the graphite-bearing metasediments, Wadi Umm Gheig area, Central Eastern Desert, Egypt

The study area is located in the central part of the Eastern Desert of Egypt and is mainly covered by different varieties of Precambrian basement rocks represented mainly by younger and older granites, metadiorite, metavolcanics, and metasediments. The analysis and interpretation of airborne gamma-ray spectrometric survey data are essentially based on the computation of the three radioelements (U, Th, and K) favorability indices, estimation of uranium migration rate percentage, variation of eU with eTh and eU/eTh ratio, and the construction of the contour map of the (eU-eTh/3.5) in the different rock units. The highest percent of uranium migration- out or leaching rate is connected with the red and pink granites of Gebel Kadabora El-hamra, metadiorite, and red and pink granites of G. Umm Rakham (− 20.8%, − 18.57%, and − 8.45% respectively), which indicates that they could represent a major U-source bodies in the area. It was observed that the metasediments and associated graphite-bearing schists west and northwest of G. Kadabora El-hamra reflect more precipitation than the other locations around the pluton (the uranium migration rates varies between 2.59 and 30%) which mean that the graphite may have acted as a reducing agent for uranium carried in oxidizing fluids (surface meteoric water) and resulted in its precipitation. In the light of the availability of uranium source, its mobility, and graphite-bearing metasediments, the area has a good potential for the possible occurrence of uranium mineralization.

Mapping upland peat depth using airborne radiometric and lidar survey data

A method to estimate peat depth and extent is vital for accurate estimation of carbon stocks and to facilitate appropriate peatland management. Current methods for direct measurement (e.g. ground penetrating radar, probing) are labour intensive making them unfeasible for capturing spatial information at landscape extents. Attempts to model peat depths using remotely sensed data such as elevation and slope have shown promise but assume a functional relationship between current conditions and gradually accrued peat depth. Herein we combine LiDAR-derived metrics known to influence peat accumulation (elevation, slope, topographic wetness index (TWI)) with passive gamma-ray spectrometric survey data, shown to correlate with peat occurrence, to develop a novel peat depth model for Dartmoor.Total air absorbed dose rates of Thorium, Uranium and Potassium were calculated, referred to as radiometric dose. Relationships between peat depth, radiometric dose, elevation, slope and TWI were trained using 1334 peat depth measurements, a further 445 measurements were used for testing. All variables showed significant relationships with peat depth. Linear stepwise regression of natural log-transformed variables indicated that a radiometric dose and slope model had an r2 = 0.72/0.73 and RMSE 0.31/0.31 m for training/testing respectively. This model estimated an area of 158 ±101 km2 of peaty soil >0.4 m deep across the study area. Much of this area (60 km2) is overlain by grassland and therefore may have been missed if vegetation cover was used to map peat extent. Using published bulk density and carbon content values we estimated 13.1 Mt. C (8.1–21.9 Mt. C) are stored in the peaty soils within the study area. This is an increase on previous estimates due to greater modelled peat depth. The combined use of airborne gamma-ray spectrometric survey and LiDAR data provide a novel, practical and repeatable means to estimate peat depth with no a priori knowledge, at an appropriate resolution (10 m) and extent (406 km2) to facilitate management of entire peatland complexes.

Airborn gamma-ray spectrometric data as guide for probable hydrocarbon accumulations at Al-Laqitah area, Central Eastern Desert of Egypt

An exploration method has been developed to understand the relation between the radiometric measurements and the subsurface petroleum accumulations, where subtle anomalous patterns of radiation flux are detected over subsurface hydrocarbon basins. This technique is mainly based on utilizing the aerial gamma-ray spectral data in the prospecting for petroleum in stratigraphic and structural traps. Al-Laqitah area, Central Eastern Desert, Egypt, was selected to apply this method on its recorded aerial gamma-ray spectrometric survey data. The method presented in this work may play a major role in making these measurements an effective contributor for finding oil and gas resources. Thorium normalization, as an exploration technique, was applied on the Foreland sedimentary cover of Al-Laqitah area to prospect the possible subsurface hydrocarbon accumulations. The DRAD arithmetic means, plus the three times standard deviations(X+3S) for the data set were computed. Any single DRAD value, within the boundary of rock units, greater than this quantity that possesses a probability of 99.87% represents a valid anomaly that is not caused by random variations in the background values. The application of these criteria has led to the identification of nine zones over the investigated area that are statistically valid. These might indicate a prospective possibility for feasible subsurface hydrocarbon accumulations and oil-bearing pay zones at Al-Laqitah area.

Ground gamma-ray spectrometric studies of El-Sahu area, southwestern Sinai, Egypt

Based on the previous airborne gamma-ray spectrometric study carried out in southwestern Sinai area, El Sahu area was selected for detail ground gamma-ray spectrometric survey. This area is considered as a good target for radioactive mineral exploration. The study area is exposed in a Paleozoic basin covered by different rocks (ranging from Precambrian to Quaternary). The ground gamma-ray spectrometric survey has been conducted along the study area through random survey. The resultant gamma-ray spectrometric maps show different levels of radioactivity over the studied area, which reflect contrasting radioelement contents for the exposed various rock types. The studied area possesses total count ranging from 2.6 to 326 Ur, 0.1 to 2.8% K, 1.7 to 316ppm eU and 0.9 to 47.5ppm eTh. The highest uranium concentrations are located in the northern and southern parts of El Sahu area. They are mainly associated with Um Bogma Formation occurrences.Uranium ratio maps (eU/K and eU/eTh) as well as ternary maps show sharp increase of eU content over both potassium and thorium contents associated with the ENE and NNW trends in Um Bogma Formation, indicating an increase in the U-potentiality than the surrounding rocks. This indicates that the mineralization in the study area may be structurally-controlled.

Ranking the geothermal potential of radiothermal granites in Scotland: are any others as hot as the Cairngorms?

Prior investigations concur that the granite plutons in Scotland which are most likely to prove favourable for geothermal exploration are the Ballater, Bennachie, Cairngorm and Mount Battock plutons, all of which have heat production values greater than 5 μW m −3 . This heat production arises from the significant concentrations of potassium, uranium and thorium in some granite plutons. A new field-based gamma-ray spectrometric survey targeted plutons that were poorly surveyed in the past or near areas of high heat demand. This survey identifies several other plutons (Ben Rhinnes, Cheviot, Hill of Fare, Lochnagar and Monadhliath) with heat production rates between 3 and 5 μW m −3 that could well have geothermal gradients sufficient for direct heat use rather than higher temperatures required for electricity generation. The Criffel and Cheviot plutons are examples of Scottish granites that have concentric compositional zonation and some zones have significantly higher (up to 20%) heat production rates than others in the same plutons. However, the relatively small surface areas of individual high heat-production zones mean that it is unlikely to be worthwhile specifically targeting them. Supplementary material: The full set of heat production data is available at https://doi.org/10.5525/gla.researchdata.302

Identifying soil landscape units at the district scale by numerically clustering remote and proximal sensed data

Identifying soil landscape units at a district scale is important as it allows for sustainable land-use management. However, given the large number of soil properties that need to be understood and mapped, cost-effective methods are required. In this study, we used a digital soil mapping (DSM) approach where remote and proximal sensed ancillary data collected across a farming district near Bourke, were numerical clustered (fuzzy k-means: FKM) to identify soil landscape units. The remote data was obtained from an air-borne gamma-ray (γ-ray) spectrometer survey (i.e. potassium-K, uranium-U, thorium-Th and total counts-TC). Proximal sensed data was collected using an EM38 in the horizontal (EM38h) and vertical (EM38v) mode of operation. The FKM analysis (using Mahalanobis metric) of the kriged ancillary (i.e. common 100m grid) data revealed a fuzziness exponent (ϕ) of 1.4 was suitable for further analysis and that k=4 classes was smallest for the fuzziness performance index (FPI) and normalised classification entropy (NCE). Using laboratory measured physical (i.e. clay) and chemical (i.e. CEC, ECe and pH) properties we found k=4 was minimised in terms of mean squared prediction error (i.e. σ2p,C) when considering topsoil (0–0.3m) clay (159.76), CEC (21.943), ECe (13.56) and pH (0.2296) and subsoil (0.9–1.2m) clay (80.81), CEC (31.251) and ECe (16.66). These σ2p,C were smaller than those calculated using the mapped soil landscape units identified using a traditional approach. Nevertheless, class 4A represents the Aeolian soil landscape (i.e. Nb4), while 4D, represents deep grey (CC19) self-mulching clays, and 4B and 4C yellow-grey (II1) self-mulching clays adjacent to the river and clay alluvial plain, respectively. The differences in clay and CEC reveal why 4B, 4C and 4D have been extensively developed for irrigated cotton production and also why the slightly less reactive 4B might be a source of deep drainage; evidenced by smaller topsoil (2.13dS/m) and subsoil (3.76dS/m) ECe. The research has implications for providing meaningful DSM of soil landscape units for farmers at districts scales where traditional methods were restrictive in terms of time and cost.

Application of 3D Euler deconvolution and improved tilt angle to the aeromagnetic data of In Ouzzal terrane, western Hoggar, Algeria

The study area is located in the western Hoggar Shield (southern Algeria). It includes the In Ouzzal terrane, which consists of Archaean metamorphic rocks. By contrast to other rocks of the Hoggar Shield, the In Ouzzal terrane represents an exception of being neither deformed nor metamorphosed during the Pan-African event, remaining as a rigid block since 2 Ga. Although, previous geophysical works in the area include an airborne magnetometer and gamma-ray spectrometric survey as well as ground gravity and magnetotelluric survey structurally, the study area has not been very well understood. In this paper, we present the interpretation results of the airborne magnetic data by using the 3D Euler deconvolution and the improved Tilt-angle methods. These results reveal the existing of fault systems (FS) occurring within the center of the study area and along the latitude of 22°; the results also suggested that the deepest fault system is oriented NE–SW and is represented by parallel major faults splitting the In Ouzzal terrane into two different parts: northern and southern. The northern part moved northwards, whereas the southern part moved southwards colliding with the Iforas unit. The interpretation confirms that the In Ouzzal terrane and the surrounding Pan-African structures are bound two by two sub-vertical lithospheric faults with the existence of dextral and sinistral faults in the west and east of the terrane, respectively.

Airborne gamma-ray spectrometric survey of environmental radiation background around Haiyang NPP, Shandong

Airborne gamma-ray spectrometric survey of environmental radiation background around Haiyang NPP, Shandong

Relationships between ground and airborne gamma-ray spectrometric survey data, North Ras Millan, Southern Sinai Peninsula, Egypt

In the last decades of years, there was considerable growth in the use of airborne gamma-ray spectrometry. With this growth, there was an increasing need to standardize airborne measurements, so that they can be independent of survey parameters. Acceptable procedures were developed for converting airborne to ground gamma-ray spectrometric measurements of total-count intensity as well as, potassium, equivalent uranium and equivalent thorium concentrations, due to natural sources of radiation.The present study aims mainly to establish relationships between ground and airborne gamma-ray spectrometric data, North Ras Millan, Southern Sinai Peninsula, Egypt. The relationships between airborne and ground gamma-ray spectrometric data were deduced for the original and separated rock units in the study area. Various rocks in the study area, represented by Quaternary Wadi sediments, Cambro-Ordovician sandstones, basic dykes and granites, are shown on the detailed geologic map. The structures are displayed, which located on the detailed geologic map, are compiled from the integration of previous geophysical and surface geological studies.

Estimation of Uranium from Multichannel Spectra in Airborne Gamma Ray Spectrometry using 1.12 MeV and 1.76 MeV Photopeaks of 214Bi – An Application to Cuddapah Basin

Abstract: Present study examines the utility of gamma rays of energies 1.12 MeV and 1.76 MeV of uranium in estimation of uranium in airborne gamma ray spectrometric survey (AGRS) in comparison to the conventional 1.76 MeV alone used world wide. As a case study, the AGRS data of northern part of Cuddapah Basin is considered. Multi-channel processing is applied on this dataset to reduce the spectral noise and use of combined 1.12 MeV and 1.76 MeV has reduced the Poisson’s related statistical error. Uranium is estimated using above two energies individually and in combination, using multi-channel processing followed by standard corrections procedure. Result indicates that a combination of both energies has given best estimation due to a reduction in overall noise which helped in demarcating geological entities and litho-contacts. This indicates the efficacy of this technique which improved the radio-geochemistry of study area in understanding the radio-elemental variation.

Determining uraniferous host rocks and minerals as a source of dissolved uranium in granite aquifers near the central Ogcheon metamorphic belt, Korea

Korea has suffered from high U concentrations in some groundwater, especially in Daejeon near the central Ogcheon metamorphic belt. However, clear explanation has not been yet reported for the uranium sources in groundwater. This study is focused on identifying the potential uraniferous host rocks and finding the exact U-minerals serving as uranium sources in groundwater near Daejeon, Korea. For this work, we performed an in situ gamma ray spectrometer survey and a laboratory microscopic study with electron micro-probe analysis. The measurements for radioactive element content did not show any prominent K- and Th-anomaly spots, but they did result in several observations of considerable U-anomalies in pegmatite and hydrothermally altered granite, in which uraninite, coffinite and uranophane were found by electron micro-probe analysis. The occurrences of U-minerals are the first such discovery except in the low-grade U deposits of the Ogcheon metamorphic belt in Korea. All observed U-minerals were intimately associated with hydrothermal alteration. The remarkably low Th/U ratios in the studied uraniferous rocks also suggest that the U enrichment was genetically related to a post-magmatic hydrothermal process. However, many of the uraniferous parts were controlled by a reducing environment and occurred near the border between graphite-rich mica-schist and Jurassic leucocratic granite. The findings on these uraniferous rocks can be used in elucidating the source of highly enriched U groundwater in granite aquifers as well as in understanding the occurrence of igneous U-minerals, which has not been previously reported in Korea.

Potential of natural gamma-ray spectrometry for mapping and environmental monitoring of black-sandbeach deposits on the Northern coast of Sinai, Egypt

The concentrations and distributions of naturally occurring radioactive materials were studied with the aim of detecting and mapping radioactive anomalies as well as monitoring the environment for black-sand beach deposits in Northern Sinai, Egypt. For this purpose, ground gamma-ray spectrometric surveys were conducted using a portable GS-512 spectrometer, with an NaI (Tl) detector, on an area 77.5 km(2) in surface area located between the cities of Rafah and Elareish on the Mediterranean Sea coast. The results revealed that the black-sand beach deposits could be differentiated according to their total-count (TC) radioactivity into five normally distributed interpreted radiometric lithologic (IRL) units denoted by U1, U2, U3, U4 and U5. The computed characteristic TC radiometric statistics of these five IRL units range from 4.67 to 9.96 Ur for their individual arithmetic means. The computed arithmetic means for the three radioelements K, eU and eTh reach 0.46 %, 2.25 and 6.17 ppm, respectively for the whole study area. Monitoring the environmental effects of radioelement concentrations on the study area showed that the mean natural equivalent radiation dose rate from the terrestrial gamma-radiation of the whole area attains 0.33 mSv y(-1). This average value remains on the safe side and within the maximum permissible safe radiation dose (<1.0 mSv y(-1)) without harm to the individual, except at three scattered points reaching more than these values. Some of the local inhabitants in the region sometimes use black sands as a building material. Consequently, they are not recommended for use as building materials, because the inhabitants will, then, receive a relatively high radioactive dose generated mainly by monazite and zircon minerals, two of the main constituents of black sands.