Ahmed Abdelhalim

Gold mining is an important strategic sector. The search for mineral reserves is moving deeper as more accessible shallow resources are discovered. Geophysical techniques are now being employed more frequently in mineral exploration because they are quick and can provide crucial subsurface information for discovering potential metal deposits, particularly in high-relief and inaccessible places. The potential for gold in a large-scale gold mining (LSGM) locality in the South Abu Marawat area is investigated using a geological field investigation that includes rock sampling, structural measurements, detailed petrography, reconnaissance geochemistry, and thin section analysis, integrated with various transformation filters of surface magnetic data (analytic signal, normalized source strength, tilt angle), contact occurrence density maps, and tomographic modelling for the subsurface magnetic susceptibilities. The benefits of remote sensing (RS) and its technology in mapping detailed rock differentiation, and characterizing physical objects on the land surface using various spatial, and spectral resolution datasets are integrated. Both aeromagnetic and measured land magnetic profiles are used to investigate the area’s present geological conditions and possible future mining localities. Results indicate that gold mineralization in the study area is linked to the altered ultramafic zones that are associated with faulting and shearing and characterized by a low magnetic susceptibility anomaly.

Kharit basin is an interior Cretaceous rift basin hosted in a Precambrian basement complex of the Arabian-Nubian shield. Satellite images and potential geophysical data previously outlined the basin without a detailed field study. Kharit area is a remote and hyper-arid area; therefore, the application of remote sensing is essential for completing the process of its geo-structural mapping. A multi-spectral optical dataset of the Landsat-8 and high-resolution images of Google Earth was integrated with the field investigation to classify the lithological units and define structures. That integration between analyzed satellite images and field investigations led to a geological map of a minimum scale of 1:50,000 for the lithological rock units and a maximum scale of up to 1:7000 for the structural mapping. The map shows an elongated NW-oriented rift basin filled by a thick deposit of Cretaceous sequences bounded from the east, west, and south by Proterozoic igneous and metamorphic rocks. Additionally, rift-related volcanic rocks were mapped along the western border fault system of the basin. The main mapped faults were delineated in three trends, NW-SE, WNW-ENE, and N-S, while several folds of NW orientations are developed as a normal drag of the main bounding faults. The Early Cretaceous extension along inherited Precambrian lineaments propagated this fault pattern and its associated folds. These structural elements configured the studied area architecture as several grabens with thick Cretaceous sequences.

This work discusses the physical, geochemical and mineralogical characterization of some kaolin resources in Sinai which are hosted in thick sandstone sequences belonging to the Lower Cretaceous Malha Formation. The characterization of kaolin samples was done by microscopic, SEM, XRD and ICP-MS analyses. The studied kaolin resources consist of kaolinite as the chief clay mineral of all the analyzed samples. Dickite and/or halloysite are subordinate TO clay minerals, whereas illite and smectite are occasionally encountered as minor clay constituents while the identified non-clay minerals include; quartz, gypsum and hematite. Ferrugination occurs mostly at the upper boundaries of the kaolin lenses in contact with the overlying sandstone beds suggesting a possible supergene activity. The high Al2O3/SiO2 ratio of 0.53 indicates the high quality of Cretaceous kaolin deposits in Sinai. The kaolin of the lower lens in Rueikna and upper lens in Salia contains Si/Al molecular ratio of 0.9 which suggests a high grade of kaolin in these two lenses. The Cretaceous kaolin is characterized by a higher contribution of LREE (Monazite signature). In spite of the very high CIA index (97.4 and 99.2), suggesting extensive limits of chemical weathering, none of the analyzed kaolin deposits displays Ce abnormality.The Lower Cretaceous kaolin of Sinai does not satisfy the international standards for paper making industries and refractory manufacturing, but beneficiation may overcome this challenge. However, some lenses have high-grade kaolin with a low percentage of iron oxides, magnesium oxides, sodium oxides, calcium oxides and Potassium oxides and a low radioactivity, hence nominated for the local refractory industry. The high-grade kaolin of Sinai fulfills the standards required for ceramic manufacturing in the global market and all kaolin lenses of the study areas can be used in ceramic manufacturing locally.

Gold mineralisation is spatially and chronologically correlated with fault/shear zones in many of the world-class gold mines. Hence, the indirect exploration for Au mineralisation is linked with shearing and complex structures in many areas. Hence, in general, the need for a rapid, effective and new technology for gold exploration that reflects the structure set-up, shear zones, faults and related structural elements is crucial in the gold industry. In this article, we present an example of an integrated approach to gold exploration in the Fawakheir-Attala gold mining prospect in the eastern desert of Egypt. Remote sensing is used to test for rock differentiation; intensive field geological investigations were conducted along several traverses. Petrographic and geochemical analysis of selected samples confirmed Au content in some localities. Moreover, magnetic methods are used extensively (either aeromagnetic or measured land profiles) to investigate the magnetic signature of the different reported rock units and their relationship with gold occurrences and deposits. Normalised source strength transformation, magnitude magnetic transforms and subsurface modelling are used to explore the inherent relation between the surface and subsurface magnetic susceptibilities. The magnetic signature of the talc-carbonate rocks is determined. The gradational contact against the serpentinite is explained. Because three current Au mines are associated with contacts/fractures, the clear relation between the contacts/fractures and the magnetic data and the comparison with the contact occurrence density COD (heat) magnetic filtered map, the present analysis workflow can now be used to suggest new locations for Au occurrences.

Groundwater is an important factor in establishing new urban communities, especially in coastal arid and semi-arid regions. Egypt is one of the world's driest countries, with hyper-arid territory accounting for 86% of the total area and arid and semi-arid terrain accounting for the rest. The present work aims to demonstrate the powerful integration of geophysical techniques to assess groundwater potentiality and suitability in Gara Oasis (GO), which describes a good example of Egypt's strategic southern extension of its arid north-western coast. Geophysical methods, including electrical resistivity and aeromagnetics, were used to evaluate groundwater resources. The study region reduced to pole total magnetic intensity map is subjected to digital filters that include derivatives, analytic signal, and tilt angle. The possible structures controlling the shallow and deep aquifers are delineated and integrated with geoelectric results. Moreover, two magnetic tomography sections are constructed to show the subsurface distribution of magnetic susceptibilities and formation boundaries. Ten vertical electric soundings (VESs) are measured and used in this study to construct four geoelectrical cross-sections. According to the results, Gara's commonly calculated subsurface resistivity model comprises six major resistivity layers. The 5th layer, in particular, is composed of Fractured dolomitic Limestone and represents a possible promising shallow aquifer. Moreover, as evidenced by various magnetic data filters, the shallow (Miocene carbonate) and deep (Nubian sandstone) aquifers are structurally controlled and regulated by a system of faults or contacts. These contacts trends NW–SE, E–W, and NE–SW as common trends emerged from the total derivative and tilt maps. Results suggest that the central part (N–S zone) together with the western side of Gara, have the most notable aquifer possibility demanded future improvement strategies.

The goal of the present study is to investigate, delineate, and evaluate the shallow Miocene groundwater aquifer with vertical and lateral facies variations in the Gara oasis, western desert of Egypt. This oasis represents a typical arid region in North Africa. Through grid texture analysis, lineament detection, edge detection, thresholding, and identifying areas of structural complexity from the filtered residual reduced-to-pole magnetic anomaly map, it is possible to outline the fracture zones that principally control the groundwater aquifers and water flow in the area. The groundwater quality and quantity are examined hydro-geochemically through nine groundwater samples that were gathered from wells and springs distributed throughout the area around Gara Lake. Measurements of physio-chemical parameters (TDS, pH, and EC) are carried out and its spatial distribution is critically studied. The results reveal that the ion-exchange process caused by water-rock interaction is the dominant process. Furthermore, the main ions in the groundwater in the study areas were Na and Cl. This might be due to evaporation or halite dissolution with the upward flow of waters through the fractures from the deep aquifer of the Nubian sandstone to the shallow aquifer of the fractured Miocene limestone.

The current study is mainly devoted to the integration, analysis, and interpretation of the available geologic, remote sensing, and potential field data (mainly magnetic) to delineate the subsurface geologic structural elements controlling the western part of Baranes, South Eastern Desert, Egypt, and its relation to the southwestern desert structural regime. Additionally, to detect potential mineralization zones for future mining plans in the study area. The Western part of Baranes has not had enough geomorphological mapping, consequently, potential discoveries of mineralization zones are very low. So, in this paper, an attempt is initiated to better understand the evolution of the geomorphology and structural regime of the region and construct a digital geological map and structural patterns showing the possible locations of mineralization zones based on the previous knowledge from similar potential sites and focus on the future economic importance of the region. To achieve this purpose, processed Landsat-8 images successfully revealed the lithological contacts and fault zones helping in distinguishing between the different rock units; moreover, the aeromagnetic data available in the area is used and several filters are applied including reduction to the pole, Euler homogeneity equation, analytic Signal (AS), and advanced grid filtering are sequentially used aiming to detect the possible subsurface distribution of mineralization zones from the integrated interpretation of magnetic susceptibilities and available geologic and remote sensing data.

This work discusses the physical, geochemical and mineralogical characterization of some bentonite resources in South El-Hammam area which are hosted in thick sandstone sequences belonging to the Lower Miocene Moghra Formation. Bentonite samples were characterized by microscopic, SEM, XRD and ICP-MS analyses. Bentonite resources in this study consist of montmorillonite as the main clay mineral of all the analyzed samples. Kaolinite also occurs as minor clay constituents. The identified non-clay minerals include; quartz, albite and calcite. The highest grade of the studied bentonite, contains Si/Al molecular ratio of 2, suggesting absence of detrital quartz. In contrary, the lowest grade of bentonite with alumina content of 15.06%, display Si/Al molecular ratio of 4.34, where free silica dominates over bentonite. The REE content of the Lower Miocene bentonite study area is strongly imparted by LREE signature. The very high CIA index (74.85 and 91.25) suggesting intense chemical weathering of source rock, which is supported by the presence of Ce abnormality, indicating that they were deposited under pluvial conditions.

Old gold mines in the Barramiya district, Eastern Desert of Egypt, are associated with NE–SW-trending ophiolitic ultramafic belts and their alteration zones (listvenitization). This paper integrates geophysical aeromagnetic and geological studies, including remote sensing technologies, to explore the potential for planning future development of gold mining in Barramiya, Central Eastern Desert (CED), Egypt. Utilizing remote sensing techniques and processed Landsat-8 images is valuable and successful in delineating the distribution of ophiolitic ultramafic belts with their associated alteration zones. Moreover, aeromagnetic data analyses were carried out to reveal the subsurface geologic setting, the extent with depth and the possible association with gold mineralization. The total intensity map was examined numerically for remanent magnetization content using the normalized source strength transformation (NSS) for proper delineation of the mineralization with depth. The reduced-to-pole map was subjected to a variety of digital filters and tomographic inversions. The results reveal the association of three previously productive gold mines with clear low magnetic anomalies and consequently low magnetic susceptibility in the Barramiya mine area and Um Slim. However, numerous new similar anomalies were recognized and need to be explored for possible gold mineralization. The estimated depths to magnetic sources using the 3D Euler technique range between 143 and 1125 m, while 506.7 m was the estimated average depth to sources. Such results suggest other possible locations and deep gold mineralization in the areas corresponding to low magnetic susceptibilities. These results agree well with the constructed geologic map, and the spatial distributions of different rock units were classified according to distinctive mineral assemblies of serpentinites and their spectral characteristics to improve their identifications.

Geophysical and geological studies play a fundamental role in the strategic and sustainable utilization of natural resources, especially that of fossil groundwater, in arid regions. The geophysical exploration of shallow groundwater aquifers is common in arid regions. In this work, a feasibility study of future development plans in the Siwa Oasis, Egypt, was carried out. A land electric resistivity survey was conducted, and approximately 14 vertical electric soundings were measured covering the Siwa Oasis, northwestern desert, Egypt. A detailed surface geology study was also conducted to study the underground water aquifer. Digital filters were applied to the reduced to pole-available magnetic data covering the area. The normalized source strength transformation and tilt depth were calculated and applied to delineate the possible structures that may control the shallow and deep aquifers in the area. The integrated interpretation showed the presence of four main geoelectric layers forming the shallow section of the Siwa Oasis down to 220 m. These layers varied in their resistivity and rock constituents from very low (0.2 Ω m) to very high (6200 Ω m) values. The calculated hydraulic parameters showed that the uppermost central area and the eastern area were the most promising areas for the required water development. Finally, based on the integrated interpretation and the estimated shallow aquifer potentiality, a land use map for the Siwa Oasis was produced to assist future strategic development of the region.

In geosciences, field observations, and survey, remote sensing applications and data analysis still need to find out a seamless approach of integration, interlinking, and storing environment. Most applications of geomatic tools in geological studies (mainly in southern countries) focus on getting information of the real world from satellite data, but do not specify the concept of the way to represent them. However, heterogeneity exists in data form of different geological components (e.g., petrography and structure analysis), measurements, spatial analysis, and classification, which make the property and relation in the perspective of integration and management non-trivial aspect. However, this paper is an attempt to figure out a geo-data management approach by using the geo-information system (GIS). The case study is South Eastern Desert, Egypt, which built up of Neoproterozoic basement rocks and experienced successive deformations. We proposed to capture different geological data and processed digital images, together with conceptual model, to facilitate a geo-spatial framework and improve the exploration and detection of lithologies, lineaments features, and find out its interlink. Therefore, the lineament number percentage and the lineament length percentage could be used as significance of rock unit chronology, where the digital foot prints of Neoproterozoic basement rocks were created.

The Neoproterozoic basement complex of Egypt outcrops in the Eastern Desert (ED) and southern Sinai, and is regarded to represent the northwestern continuation of the Arabian–Nubian Shield (ANS). The area west of Berenice has been given little attention, although it represents the key to understanding the geologic history of the South Eastern Desert and the entire ED. The present work is an integrated study using remote sensing (Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data imagery) and field-structural data to assess their utility in lithologic mapping and in detecting alteration mineral zones with considerable accuracy. A false-color-composite image, color-ratio composite image, decorrelation stretch, mafic index (MI), and quartz index (QI) were used to discriminate and map the various rock units. Correlation of False-color images of the ASTER band combination (7, 3, 1) with previous lithological mapping studies of the study area allow preliminary discrimination of different lithologies and drawing a base map. Subsequently, ASTER band ratios tested (4/1, 3/1, 12/14) and (4/7, 4/6, 4/10) with the ground truth data were used to refine the base map and construct the digital detailed geologic map. Petrographically, the investigated rock samples show kaolinite, chlorite, and epidote in alteration zones. The spectral angle mapper (SAM)-supervised classification using reference spectra of the USGS spectral library was used for detecting alteration zones. For verification, total accuracy assessment was carried out to evaluate the band combination and band ratios used in the lithologic mapping. That reached to 85.01% for band ratio 4/1, 3/1, 12/14 in RGB.

Estimation of finite strain and microstructural analysis of deformed rocks are keys to better understanding deformational processes and related structures in a variety of scales started from microscopic fabric development to regional-scale structures. In the present work, we carried out the quantitative calculation of strain using the Rf/φ and Fry methods for quartz, feldspar and mafic grains (e.g. biotite and hornblende) from twenty two collected samples for granitic gneiss, amphibolite and hornblende schist samples from the Um Junud area situated in south Eastern Desert of Egypt. Forty four thin sections were prepared and measured by using finite strain methods. The strain data indicate high to moderate ranges of deformation of the amphibolite to granitic rocks. The axial ratios in the XZ section range from 1.74 to 4.37 and 1.50 to 4.46 for the Rf/φ and the Fry methods respectively. The finite strain direction for the long axes displays clustering along N to WNW trend, and shallow WNW plunging in the majority of the studied samples. The short axes are found to be subvertical associated with a subhorizontal foliation. It is concluded that finite strain is of the same order of magnitude for various lithologic units outcropping in the area, and that contacts were formed under semi-brittle to semi-ductile deformation conditions. Thus, the finite strain accumulated during superimposed deformation on a previously nappe structure assemblage, which pointed out that these contacts were created during the accumulation of finite strain. This result is inconsistent with the generally believed that nappe creation in orogens carried out by simple shear deformation.

The Cretaceous Nubia sandstone aquifer is the main aquifer in East El-Oweinat area along the Egyptian–Sudanese borders and in NE Africa. East El-Oweinat project has been recently considered one of the main agricultural projects in the southwest of the Egyptian Western Desert. So, the hydrogeological assessment for the Nubia aquifer in East El-Oweinat area has been done through studying and characterising the hydraulic parameters and step-drawdown test. The well and aquifer losses coefficients (C and B, respectively), the specific capacity, and the well efficiency as well as the aquifer and aquitard thickness have been estimated and traced through a total of 46 wells that have been distributed through the study area in two sectors, southern and northern. For the purpose of further exploration, the effective porosity (∅), hydraulic conductivity (K), and transmissivity (T) have been estimated for the wells in the northern sector. In addition, an aquifer assessment quality index has been introduced to assess and to rank the studied aquifer. Therefore, it is concluded that the hydraulic and the step-draw down parameters as well as the aquifer and aquitard thicknesses are prospective for further exploration to the north and the east of the northern sector in the study area. The well efficiency is mostly affected by the studied parameters, particularly the well loss coefficient, the hydraulic parameters and the well design as well. GIS approach and ArcGIS software have been applied to delineate the spatial distribution of the well performance characteristics, in order to compare between the studied groundwater wells and to integrate the different-acquired data. A set of isocontour maps have been introduced to match the lateral variation of the studied parameters and the aquifer potential to refer to the best direction for further underground water exploration.