Damietta University Faculty of Science Geology Department New Damietta Egypt
h.aboelkhair@du.edu.eg
Dr. Hatem Aboelkhair was a senior Geophysicists in Uranium exploration at Nuclear Materials Authority of Egypt from 1994-1999. He is now senior lecturer in Geophysics at Mansoura University where he teaches Geophysics and Remote Sensing. Recently he worked at Geological Survey of Japan (GSJ) for one year in Remote sensing research group from 2008-2009.
Abstract: Airborne geophysical surveying is a remote sensing technique that is used for measuring the variation of different physical or geochemical parameters of the earth such as distribution of magnetic minerals, electric conductivity and radioactive element concentration.
Bahariya Oases area is located in the northern part of the Western Desert of Egypt It is situated almost 160 km to the west of the Nile Valley. The Bahariya Oases area displays a special importance in recent years due to the discovery of economic iron ore deposits in El-Gedida and Nasser areas as well as the discovery of petroleum in economic quantities in a nearby area. The present book aims essentially to the analysis and interpretation of the aerial gamma-ray spectrometric and magnetic survey data recorded over the Bahariya Oases area. These analyses and interpretations are mainly employed to produce radioelement mapping, define mineral and petroleum exploration potentiality as well as environmental monitoring.
Abstract: 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 km2 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 yâ1. This average value remains on the safe side and within the maximum permissible safe radiation dose (<1.0 mSv yâ1) 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.
Abstract: The present study deals with the analysis of data from a ground magnetic survey that was conducted in the Abu-Rodaym area of the Southwestern Sinai Peninsula, Egypt. This survey was carried out to delineate the subsurface structural framework, and to identify the thickness of the sedimentary basin of the study area. Locating these structures, and determining the localities of maximum sedimentary thicknesses that consist mainly of sandstone, serves as a preliminary process in exploring the confined aquifer beneath the surface of the Abu-Rodaym area. This will greatly benefit Bedouins who suffer greatly from a lack of water in the driest region in the country. The processing, analysis, and interpretation, of the total intensity magnetic data shows that there are three sets of faults striking mainly in the N-S, NW-SE, and NE-SW, directions. The depth to the basement surface was found to fluctuate from about 45 m, to more than 100 m, beneath the ground surface. It was also found that the variations in magnetic observations were produced by the striking structures that are mainly responsible for the variations in thicknesses of the sedimentary rocks in the area.
Abstract: The shallow subsurface structures of the offshore Nile Delta particularly in the southeastern Mediterranean were dealt through the interpretation of 40 two-dimensional seismic reflection lines. The interpretations of seismic reflection data indicated that the principle sedimentary processes affecting the study area include three main structural groups according to their origin and development. The first group of structures comprises of gravity-driven structures, which include slides, slumps, turbidities, and debris flow. Slides are present in three different forms on seismic sections: slide sheets, slides with scar, and wedges of slide materials. Slumps have many geometrical shapes: lenses, spoon-shaped slumps, and slumped blocks bound by growth faults. Debris flows are present as transparent unit (due to the dispersion of seismic waves at debris boundaries), whereas turbidities appear on the seismic profiles, which are formed of closely spaced parallel thin reflectors analogous to their thin stratified bedded layers. The second group of structures is syn-depositional structures, which include growth faults, and tilted and rotated fault blocks. Growth faults are listric in shape and usually dip seaward; displacements along the fault plane increase with depth. Some of these faults are incipient, and some are complicated and intersected by secondary antithetic faults. Most of the growth faults soles out basin wards and in the evaporites layer. Fault blocks are formed due to the Messinian evaporite movement vertically and horizontally due to its mobility as a consequence to the pressure resulted from the overloading of Pliocene sediment. The third group of structures comprises evaporite flow structures such as diapiric structures and graben collapse structures. The surface of the Messinian evaporites was folded during its flow as a consequence to the lateral compression acted on the mobile strata of the Messinian evaporites to form diapiric triangular structures and creates a stress zone faulting and fractures system. These conditions led to the formation of collapse structures or graben collapse structures.
Abstract: In this paper, an attempt was tried to study the relation between radiogenic heat production rate (RHPR) that derived from gamma-ray spectrometric data and the kinetic surface temperature KST, which was calculated from the thermal emission and reflection radiometer-thermal infrared (ASTER-TIR) imagery applied on Elmissikat-Eleridiya district. This area is considered one of the most important uranium localities in the Central Eastern Desert of Egypt. The gamma-ray spectrometric data including both airborne data and in situ measurements concurrent with the collection of 20 rock samples were used to determine the rock density. The ground gamma-ray spectrometry has been conducted using GS-256 spectrometer at the same locations of rock samples. The gamma-ray spectrometric data (airborne and ground) beside rock density data were used for calculating RHPR. Alongside, pairs of daytime and nighttime ASTER-TIR images were collected and surface kinetic temperature for both day (daytime kinetic surface temperature (DKST)) and night (nighttime kinetic surface temperature (NKST)) were derived by using reference channel emissivity technique. The study showed a relative higher RHPR within syenogranite (4.2 up to 6 μW/m3) than other rock units. Besides, the KST of syenogranite ranged from 33 to 48 °C in daytime and between 7 and 17 °C at night. Comparing all results, no clear relation between RHPR and KST is evident. This is due to the very weak RHPR that is not sufficient to affect the surface heat temperature, which can be remotely sensed by ASTER satellite TIR data. This factor in addition to other factors such as: structural elements, topography, geographic locations, shading and scattering, rock moisture and density, can strongly affect the surface temperature. In conclusion, these results could be improved in areas of very high radioelement concentrations, especially 235U and through the use of the enhanced spatial resolution of future satellite TIR imaging instruments.
Abstract: High-resolution gamma ray spectrometry was exploited to locate the potential radioactive targets at Kab Amiri granite pluton, Central Eastern Desert, Egypt. The Kab Amiri pluton forms a concentric granitic body of monzogranite to syenogranite composition intruded into mafic-ultramific rocks. To identify and detect anomalous concentrations of natural radioactive elements in the study area, contour maps of equivalent uranium (eUâppm), equivalent thorium (eThâppm), potassium (K%) and their geochemical ratios (eU/Th, eTh/K and eU-eTh/3.5) as well as standard deviation map of uranium were constructed and interpreted. Qualitative and quantitative interpretations of the spectrometric survey data revealed the presence of seven radioactive anomalies in the south of the studied area. These anomalies could be related to the prevailing faulting directions NE and ENE fault trends. The southernmost anomalous zone is related to high episyenitization and uranium concentrations. It exhibits a sharp increase in the eU concentrations reaching 370âppm resulting in a high eU/eTh ratio reaching 4.5 and characterized by oval shape trending in the NE direction. Constructing the contour map of the (eU-eTh/3.5) was helpful in defining the trends of uranium migration and enabling the delineation of the limit between the negative contours (leaching) and positive contours (deposition).
Abstract: 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 yâ1) recommended by the International Commission of Radiological Protection.
Abstract: In situ gamma spectrometric measurements have been performed to characterise the natural radiation that emitted from the stream sediment feldspars in Wadi El Missikat and Wadi Homret El Gergab, Eastern Desert, Egypt. The measurements of potassium (K, %), equivalent uranium (eU, ppm) and equivalent thorium (eTh, ppm) were converted into specific activities and equivalent dose rate. The average specific activities were 1402 Bq kgâ1 for K, 113 Bq kgâ1 for eU and 108 Bq kgâ1 for eTh in Wadi El Missikat, while they were 1240, 104 and 185 Bq kgâ1 in Wadi Homret El Gergab. The calculated outdoor average effective dose rates was 1.1 mSv yâ1 in wadi El Missikat and 1.3 mSv yâ1 in Wadi Homret El Gergab. The terrestrial-specific activities and effective dose rate levels of the natural radioactivity in the two areas lie within the international recommended limits for occupational feldspar quarry workers. On the other hand, these results indicated that irradiation is higher than the allowable level for members of the public. Therefore, quarrying the feldspar sediments from these locations as ceramic raw materials may yield an undesired impact on the environment, especially through the indoor applications.
Abstract: Two significant airborne gamma ray spectrometic (AGRS) statistical parameters, i.e., the arithmetic mean and the standard deviation, were computed for all lithologic units and formations of the Bahariya Oases area, Northern Western Desert, Egypt. The results ascertain that the maximum AGRS values are associated with sabkha sediments, Bahariya Formation, basalt flows and sand dunes. The intermediate values are correlated with El-Heiz, El-Hefhuf, Qazzun and Naqb formations. The minimum values are connected with Khoman Chalk and El-Hamra formations. The AGRS records were found to vary from one type of rock to another and to some extent between units of the same rock type too. On the aerial total-count (TC) radiometric maps, the records change from 6.2 to 69.36 μR/h. On the potassium map, the values range from 0.05% to 4.35%. On the equivalent uranium (eU) and equivalent thorium (eTh) maps, the records oscillate from 0.12 to 7.4 ppm and from 0.28 to 8.4 ppm, respectively. Concerning the Bahariya Oases area, the calculated arithmetic mean natural dose rate values originating from the terrestrial gamma radiation were found to range from 0.14 to 0.26 mSv/year and where the maximum value attains 0.62 mSv/year. These values remain on the safe side and within the maximum permissible safe radiation dose without harm to individuals, with continuous external irradiation of the whole body.
Abstract: ASTER level 1B (radiance at the sensor) TIR-bands and level 2B04 (surface emissivity) data were analyzed to detect four of 14 rare-metal-enriched albite granite, which are classified as I-type magnetite-series (G3 type) granites in the Central Eastern Desert of Egypt. Analysis of the shapes of laboratory emissivity spectrum
of albite granite samples measured by portable emission spectrometer and albite mineral spectra from ASTER spectral library at the website of JPL of NASA showed that, albite granite samples has a higher emissivity in bands 12, 13 and 14 than in bands 10 and 11. To identify and map this type of granite, Quartz Index, as well as band ratios, band ratio combination and band combinations were used, based
on the shapes of the analyzed emissivity spectrum of albite granite samples and albite mineral. The Quartz Index (QI) was high for quartz-rich/feldspar poor rocks and was low for K-feldspar or gypsum-rich rocks. Albite rich granites were detected as dark pixels in the QI image. The proposed band ratio b12/b11 clearly identified the albite granite bodies as dark regions. False color images of band combination of
14:12:10 and 12:13:11 in R:G:B clearly mapped the albite granite bodies as light brownish yellow and light greenish regions respectively. A new ASTER colored composite band ratio combination b12/b13:b11/b12:b14/b13 as R:G:B is applied successfully for mapping albite granite in the study area. This new combination clearly separated albite granite as pinkish magenta color. An ASTER scene covering the study area acquired on a different date was used to determine the effect of atmospheric and surface temperature conditions on the ratio and the mathematical band operation. The results indicated no significance differences.
Abstract: A new exploration method was developed by Saunders et al. (1993) which uses surface and aerial gamma-ray spectral measurements in prospecting for hydrocarbon accumulations in stratigraphic and structural traps. This method was applied on the recorded aerial gamma-ray spectrometric survey data of the Bahariya Oasis area, Northern Western Desert, Egypt. The study area displays a special importance in recent years, due to the discovery of economic iron ore deposits in Algedida and Nasser areas as well as petroleum in economic quantities in a near-by area. The application of this method on the survey data led to the identification of nine zones along nine profiles over the study area, which show valid anomalies. These zones may define possible subsurface hydrocarbon deposits within the area under consideration.
