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This paper discusses the geochemical constraints on genesis of dispersed mineralized quartz-fluorite veins (QFV) at south west Sinai Peninsula, Egypt. These veins range from colorless to pale to deep violet in color and extend continuously and/or discontinuously in NE-SW, E-W, N-S, and NW-SE trends. They exhibit varying thicknesses ranging from a few centimeters to approximately 0.3 m. The scanning electron microscope (SEM) analysis has revealed the existence of secondary uranium minerals, notably kasolite Pb(UO2)SiO4.(H2O), in association with other minerals such as galena (PbS), atacamite (Cu2Cl(OH)3), and fluorite (CaF2) within the quartz-fluorite veins (QFV). Furthermore, the SEM analysis indicates a significant presence of fluorine incorporated into the biotite lattice of the host granitic rocks. Geochemically, there is a reasonable difference between the host granitic rocks and QFV, especially, silica and alumina contents. Also, some trace elements experienced enrichment in QFV such as Cu, U, Pb and Ag. The chondrite normalized pattern of QFV rare earth elements (REE) shows conspicuous negative Tb anomalies while the host rocks showed negative Eu anomalies. It is noticeable that there is a closed relation between uranium and fluorine in QFV. The Th/U ratios are < 1 in QFV samples indicating that the QFV had not been derived from magmatic origin. Furthermore, the REE and the mineral assemblages of QFV imply to hydrothermal origin (meteoric water) at shallow depth and low temperature < 200 °C under oxidation condition (epithermal genesis). [ABSTRACT FROM AUTHOR]

In Egypt, the Middle Eocene time represents a prolific interval for the evolution of Nummulite carbonate platforms on the southern continental paleo-margins of the Tethys. The prevalence of Nummulites has produced a significant piles of carbonate sediments represented mainly by many different facies belts interbedded with silt-sized nummulithoclastic packstones facies. These carbonates are considered as important reservoirs of hydrocarbons in the Mediterranean area, as both in offshore Tunisia and Libya. In Egypt and especially in the target area, these carbonates have been carefully studied in the field in both central Eastern Desert and west-central Sinai. On the other side, the petrography of these facies shows an exceptional richness in nummulithoclasts facies. The nummulithoclasts are spreading vertically and horizontally within parautochthonous to allochtonous Nummulite banks with a clear decrease in grain size from the shallowest (south) to the deepest (north) areas of the carbonate platform. The studied Nummulite build-ups exhibit several physically controlled sedimentary structures and bio-fabrics that could be detected on micro- and macro-scales. These structures highlight the roll of abiotic and biotic agents as triggering mechanisms in fragmentation of Nummulite tests leading to silt-sized bioclasts (nummulithoclasts). Candidates of such triggering mechanisms are storm surges and compaction with diagenetic processes (i.e., pressure solution and bioerosion). Storm currents swept away sediments from shallow near-shore to outer-ramp deeper environment. They were accumulated in a coevally formed small half-graben basins (sediment traps). Microfacies data proved that Nummulite banks were accumulated within the back-bank/lagoonal, bank-core, and fore-bank open marine settings. The small Nummulites (A-forms) with Alveolines were occupying shallow, euphotic waters, but ovate and robust tests lived and accumulated in middle waters indicating the influence of currents with wave-winnowing processes. The fore-bank (distal assemblages), were colonized by nummulitid with orthophragminid shells in the open marine deeper portion of the photic zone. Palaeogeographic reconstruction maps during the Middle Eocene indicate that Egypt was situated in tropical, storm-dominated paleo-latitudes, which were controlled by a global warming. This global warming enhanced the sea surface temperature. Comparison between nummulithoclasts and other bio-sedimentary facies in Algeria, Morocco, North America, South Tibet, and Oman indicates clear similarities concerning the processes implied in shell fragmentation in relation with a global warming. [ABSTRACT FROM AUTHOR]

Satellite images are used, among other functions, for geologic feature extraction. Scientists have developed advanced, cutting-edge, and reliable data extraction processing procedures, such as machine learning and edge detection methods, as a result of the rapid development in the volume of remote sensing data received from various platforms. The use of the optimal edge detection techniques is crucial for mapping the lineaments because it is thought that hydrothermal alteration may be related to faults and fractures that are pathways for hydrothermal solutions. Efforts were made in this direction by evaluation and comparison of different optimal edge detector algorithms using the first principal component analyses of ASTER imagery on Gattar area in the Northern Eastern Desert of Egypt. The lineaments identified in the Gattar batholith show mainly the NNE–SSW and NE–SW and nearly E–W strikes as major directions and the NW–SE strike as a minor direction where the dominant structures controlling the mineralization are NNE–SSW and NE–SW trending faults. The (LoG) method was found the most accurate and well-matched with the field investigation in the study area. Machine learning methods are robust in processing spectral and ground truth measurements against noise and uncertainties. Four popular and recently established classification machine learning methods are applied and compared in the area for mapping the lithologic units, and their accuracy was evaluated using a confusion matrix; they are maximum likelihood classifier (MLC), Mahalanobis distance classification (MDC), neural net classification (NNC), and support vector machine (SVM). The results showed that both (MLC) and (SVM) were better at discriminating all the lithological units in the area. As a result, it was established in this study that the most appropriate methods specified for automatic lineament extraction and machine learning successfully map geological structures and lithological units in the study area and can be achieved in different geographical locations. [ABSTRACT FROM AUTHOR]

The Eastern Desert in Egypt is a significant gold-mining region, and its gold mine is one of the world's oldest. The presence of tailings and slag piles in the vicinity of historical mining sites can give rise to environmental risks for the surrounding soil, water, and air. These hazards primarily result from erosion and the interaction between these materials and runoff waters. The mining practices employed in the past involved the storage of ore underground and subsequent surface crushing. However, this approach has resulted in heavy metals and chemicals buildup within soils and sediments. The concentrations of various metals, trace elements, and toxic substances, including Fe, As, Au, Ag, Cu, Co, Ni, Mn, Pb, Cd, CN, Hg, Mo, Li, and Cr, were analyzed in samples collected from the Fawakhir and El Sid sites. The abundance of metals and toxic substances measured in these sediments exhibit a decreasing trend as follows: Fe > As > Cr > Au > Mn > Pb > Ni > Cu > Li > Co > Mo > Cd > Ag > Hg > CN. These toxic elements can persist for long periods and are widespread in natural and artificial sources, including parent rocks, water, atmosphere, and mining activities. Significant quantities of heavy metals, including arsenic (As), iron (Fe), and mercury (Hg), along with highly toxic chemicals such as cyanide (CN), were detected within the silver and gold deposits. The presence of these hazardous substances poses a significant risk to both the local ecosystem and human well-being. Soil contamination in the area can be attributed to various factors, including natural erosion processes, ancient mining activities, and the abandonment of tailing deposits. [ABSTRACT FROM AUTHOR]

New geochemical data of the Iron Oxide-Copper–Gold (IOCG) mineralization and its host rocks in the Dara area, North Eastern Desert of Egypt, are investigated for a better understanding of their petrogenesis. The host rocks are classified into metagabbro-diorite and I-type younger granitoids (monzogranite and alkali feldspar granites). The metagabbro-diorite rocks are volcanic arcs with calc-alkaline affinity and were generated by partial melting of mantle related to the subduction zone. The monzogranite and alkali feldspar granite are metaluminous to weakly peraluminous with calc-alkaline and highly fractionated I-type affinity, respectively. The monzogranite was suggested to be generated from the partial melting of the lower mafic crust, whereas the alkali feldspar granites were from the upper continental crust. IOCG mineralization at the Dara prospect is confined along contacts between the metagabbro-diorite and monzogranite rock types in the form of quartz and quartz-carbonate veins surrounded by alteration zones. The IOCG mineralization is structurally controlled where the quartz and quartz-carbonate veins follow rejuvenation NW–SE compressional Najd fault to E-W and NE-SW extensional fault systems. The hydrothermal mineralization consists of magnetite, hematite, specularite, quartz, calcite, chalcopyrite, minor pyrite, and native gold. Hydrothermal alteration is subdivided into inner sericite-rich and outer chlorite-rich zones. Chemical discrimination using CCPI (chlorite-carbonate-pyrite chemical index), AI (alteration index), and mass balance calculation suggests a redistribution of most elements during alteration without extensive elemental changes except for Eu and Ho. The field, mineralogical, and geochemical features advocated that the mineralization is akin to be related to the Iron Oxide-Cu-Au (IOCG) system that could be linked to the post-collisional tectonic setting of the Arabian-Nubian Shield (ANS). [ABSTRACT FROM AUTHOR]

This article carried out an integrated study of the mineral composition, whole-rock elemental geochemistry, and zircon U-Pb dating for the rift-related alkaline volcanoes at Wadi Natash, South Eastern Desert (SED), Egypt, to investigate their magmatic evolution and origin. The Natash volcanoes (NV) are characterized by explosive and extrusive polyphases trending in NW-SE with a diverse compositional range of basalts, trachyandesites, trachytes, and rhyolites/comendites categorized by distinct high concentration of HFSEs and REEs. Zircon U-Pb dating offers ages of 96 ± 2.5 to 86 ± 2 Ma, constraining Late Cretaceous eruption of the NV. The basalts have high HFSE, REE, and Nb/U ratios similar to Nb-rich basalts derived from OIB source. The trachyandesites/trachytes and rhyolites have high ratios of Ga/Al (8–12), HFSF (Nb = 79–283 ppm, Zr = 433–1807 ppm), and REE (671–728 ppm) and low concentrations of Sr, P, Ti, and Eu which are analogous to typical A1-type granites. The Nb enrichment in all rock types (81–283 ppm) is controlled by both magmatic and hydrothermal processes. The NV were originated from an enriched lithospheric mantle source metasomatized by asthenosphere-derived fluids and then experienced fractional crystallization (FC) with no significant input of crustal contamination. Petrographical and geochemical criteria elucidate olivine + clinopyroxene as the main fractionated phases, followed by hornblende + plagioclase + Fe-Ti oxides + apatite during the more evolved stage. In addition to FC, the phenocryst textures conform a variety of magmatic processes, such as multi-crustal storage, crystallization, volatile fluxing, and degassing and magmatic evolution in open systems with a fluctuating temperature, pressure, and water. The geothermobarometic data point to a polybaric-polythermal system with numerous magma residence regions fluctuating from lower-middle (1.4–1.25 GPa and 1154–1136 °C) to shallow crustal levels as demonstrated by plagioclase crystallization (0.75–0.26 GPa and 1048–980 °C) and Fe-Ti oxides (937–904 °C) when magmas ascend to the surface. The evolution of the NV can be linked to mantle plume magmatism and extensive Mesozoic alkaline ring complexes recorded along the Egypt/Sudan border, Northeast Africa, and Northern Arabia in an extensional setting, highlighting that the assembly of the Rodinia supercontinent might have been finalized prior to ca. 86 Ma. [ABSTRACT FROM AUTHOR]

Expansive soils exhibit significant volumetric changes as the water content varies. During the season of rainfall, they expand when they absorb water, and during the dry season, they shrink when it evaporates. Due to Egypt's lack of experience in characterising and managing problematic shrink-swell soils, several problems may be observed in some of the structures constructed as part of development projects. Consequently, it is important to measure swelling properties, such as the swelling potential, swelling pressure, swell limit, shrink limit and Shrink-Swell index. In order to enhance the properties of expansive soil, geotechnical researchers have suggested a number of solutions. The present study discusses the treating of expansive soils collected from a variety of locations in Egypt. Expansive soil samples were collected from five sites such as Fayoum, the 6th of October, Qena, El-max Elkebly (El-Wadi El-Gedid) and BeniSuif. The treatment strategy is based on mixing the expanding soil with coarse-grained soil of a specific gradation. Each soil sample set is mixed with coarse-grained soil at percentages of 0%, 20%, 40%, 60% and 80% by weight to generate five different mixtures. The results indicated that the swelling potential, swelling pressure, swell limit and shrink-swell limit of the five tested soils decreased as the percentage of coarse sand in the swelling soil increased from 0 to 80%. In addition, five preliminary correlations are established between the coarse-grained fraction of expansive soil and the percentage reduction in swelling potential, swelling pressure, swell limit, shrink limit, shrink–swell limit of expansive soil. Additionally, the experimental models were verified and simulated using the 2-D finite element software PLAXIS (2D), as well as to assess the validity of the selected computational techniques. The results demonstrated that PLAXIS (2D) is an effective tool for improving expansive soil properties. [ABSTRACT FROM AUTHOR]

To reconstruct the paleoclimate in North Africa during the Paleocene, the calcareous nannofossils were quantitatively analyzed at higher resolution from the stratigraphic succession of Gebel Nezzazat (west central Sinai, Egypt). The studied interval extends from NP4 to NP8. Zone NP4 can be subdivided into four subzones from base to top: NTp7B, NTp8A, NTp8B, and NTp8C. The base of the Selandian age is located at the base of NTp8B (Second Radiation of Fasciculithus). The Selandian/Thanetian boundary (S/T) is tentatively placed at the base of Zone NP7/8. The identified nannofossil zones were compared with that of the Tethyan region for the Danian/Selandian boundary. The calcareous nannofossil assemblages were used as indicators for medium-term climatic fluctuations. The pre-Danian (LDE) is dominated by the cool-water Zeugrhabdotus sigmoides and Neochiastozygus modestus, while the post-Danian interval is dominated by Coccolithus pelagicus and Ericsonia subpertusa. Before the onset of the Selandian-Thanetian boundary, a marked shift in the nannofossil species was observed, where Fasciculithus increased significantly, while marker Danian-Selandian genera (e.g., Lithoptychius Neochiastozygus, Chiasmolithus, and Cruciplacolithus) decreased dramatically. Non-Metric Multidimensional Scaling (nMDS) and permutational analysis of variance (PERMANOVA) in addition to the Temperature and Nutrient indices (TI and NI) indicated a marked difference between the warm eutrophic nannofossil assemblages at the Danian/Selandian (D/S) and the Selandian/Thanetian (S/T) transitions and the eutrophic cold-water assemblages during the background sedimentation. A sharp increase in sea surface temperature and decrease in nutrients was observed at D/S and represents the Latest Danian Event (LDE), while the second warming event was started prior to the Selandian and may represent the Early Late Paleocene Event "ELPE." The sea-level lowstand may have limited water circulation, where surface water fertility decreased significantly. Consequently, nannofossil diversity decreased. The rapid recovery after the LDE was attributed to the radiation of warm-water taxa. [ABSTRACT FROM AUTHOR]

Shale-rich reservoirs present a long-standing challenge for reservoir geologists because the clay minerals often induce a large-scale heterogeneity in the reservoir pore system. This work aims to understand the impact of clay distribution and mineralogy which would enhance the predictability of the best reservoir facies. We integrate seismic, well-log datasets to investigate the petrophysical characteristics of the clay-rich Cenomanian Clastics in the GPY oil field, north Western Desert of Egypt. These Clastics comprise the sandstone intervals which are the most prolific hydrocarbon reservoirs. Seismic data were used to interpret the main structural patterns as well as the different seismic facies. The well log data were utilized to interpret the lithologic variations and the type of clays in the reservoir as well as the different petrophysical parameters. Based on variations in their lithological and petrophysical characteristics, the Bahariya sandstones were sub-divided into three different rock units: Bahariya-3 (B-3), Bahariya-2 (B-2), and Bahariya-1 (B-1), separated by thick laminated clay intervals. AR/G Member is dominated by clays with relatively lower reservoir quality. Spectral gamma ray log values reveal that smectite is the dominant clay mineral in all the studied intervals. Laminated clays are dominant in B-1 and B-2 units, whereas, B-3 unit and Abu Roash G Member are enriched in structural clays. The quartzose sand content decreases from B-3 to AR/G and clay content increases from B-3 to AR/G. Therefore, the best reservoir facies and fluid flow conduits with best pore system characteristics are hosted in B-3 and the smectite clay streaks act as a good seal for hydrocarbons in the quartzose sandstone pay zone. [ABSTRACT FROM AUTHOR]

Many industrial activities dispose of their waste in the sand soil of the El-Khatatba region of Egypt. There is a need to reuse the site in building markets and shopping stores. Because it is difficult to obtain leachate from an open dumping site, we use hazardous landfill leachate (HLL) from an industrial waste landfill to identify changes in the geotechnical properties of soil. The HLL was obtained from Al-Nasreya Center, Alexandria, Egypt. This study, therefore, was directed to assess the effects of HLL on the geotechnical properties of the poor-graded sand (SP) soil. The natural sand was artificially mixed with HLL at different concentrations of 0%, 25%, 50%, 75%, and 100%. The results revealed that the permeability coefficient (k) of the natural sand decreased significantly from 1.28 × 10−2 to 0.8 × 10−2 cm/s when HLL concentration increased to 100%. Similarly, HLL contamination obviously reduced the angle of internal friction (φ) of sand. The optimum moisture content (OMC) of the natural sand decreased from 12 to 10%. In contrast, the maximum dry unit weight (MDD) of the natural sand increased slightly from 18.33 to 18.9 kN/m3 due to the increase of HLL concentrations from 0 to 100%. The change in the sand structure was interpreted by detailed analyses using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Based on these findings, HLL was found to modify the geotechnical properties of the studied sand. [ABSTRACT FROM AUTHOR]

In this research, we have compiled a catalogue of the worst tsunami earthquakes that caused destruction and losses in the northern coastal region of Egypt. Variability in seismic source parameters reflects the level of cognitive uncertainty that exists because most of these destructive tsunamis, if not all, occurred in the pre-instrumental period. We also synthesized a set of hypothetical tsunamis constrained by seismotectonic knowledge of the area of influence to embrace the uncertainty. We also collected the topo-bathymetry information available to make a simulation on the scale of the Egyptian north coast. The multiple scenarios were computed considering references and hypothetical scenarios, and results were presented in maps and tables for wave heights, inundation depth, and estimated arrivals. Comparisons were made between the results calculated in this study and those from previous studies. These were done to identify and measure the reasons for the difference and similarities. The results may contribute to developing risk reduction strategies and a national early warning system. Variability in tsunami intensity measures is prepared for the hypothetical scenarios due to the difference in the fault's magnitude, location, and geometry. Also, for the first time, temporally based scenarios the sea-level rise and delta sinking were considered in order to highlight the importance of multi-risk analysis for the region of interest. The insight on incorporating other hazards of the temporal resolution indicates a significant increase in inundated areas and wave height. Therefore, proper and detailed estimation of multi-hazard maps for the coastal region of the Nile Delta is highly required to protect the ongoing sustainable development and protect the people and their assets. [ABSTRACT FROM AUTHOR]

In this research, we have compiled a catalogue of the worst tsunami earthquakes that caused destruction and losses in the northern coastal region of Egypt. Variability in seismic source parameters reflects the level of cognitive uncertainty that exists because most of these destructive tsunamis, if not all, occurred in the pre-instrumental period. We also synthesized a set of hypothetical tsunamis constrained by seismotectonic knowledge of the area of influence to embrace the uncertainty. We also collected the topo-bathymetry information available to make a simulation on the scale of the Egyptian north coast. The multiple scenarios were computed considering references and hypothetical scenarios, and results were presented in maps and tables for wave heights, inundation depth, and estimated arrivals. Comparisons were made between the results calculated in this study and those from previous studies. These were done to identify and measure the reasons for the difference and similarities. The results may contribute to developing risk reduction strategies and a national early warning system. Variability in tsunami intensity measures is prepared for the hypothetical scenarios due to the difference in the fault's magnitude, location, and geometry. Also, for the first time, temporally based scenarios the sea-level rise and delta sinking were considered in order to highlight the importance of multi-risk analysis for the region of interest. The insight on incorporating other hazards of the temporal resolution indicates a significant increase in inundated areas and wave height. Therefore, proper and detailed estimation of multi-hazard maps for the coastal region of the Nile Delta is highly required to protect the ongoing sustainable development and protect the people and their assets. [ABSTRACT FROM AUTHOR]

In the Wadi Qena region, the digital elevation model (DEM), aeromagnetic, and magnetotelluric data are processed and examined to outline surface water flow patterns, the subsurface structures, demonstrate their effects on the groundwater flow direction, and assess the groundwater aquifer thickness and the relationship between subsurface structures and the inherited surface water flow (drainage pattern). Wadi Qena's drainage pattern and watershed basins were delineated using satellite digital elevation data in order to accomplish these objectives. The first vertical derivative transformation was used and examined to determine the prevailing northwest-southeast and northeast-southwest structural trends impacting the region. In order to handle aeromagnetic data, it is necessary first to reduce the observed magnetic data such that they correspond to the reduced magnetic pole (RTP). The two-dimensional analytical signal technique was used to discover that the depth of the basement rocks, which in the research region serve as the bedrock of the overlying groundwater aquifer, ranges from 101 to − 1165 m relative to sea level. This information was obtained by measuring the distance from the earth's surface to the bedrock. To further define the accurate subsurface geological model in the region, the conducted magnetotelluric survey in the area was interpreted using the 1-D inversion technique, and the results were coupled with the existing drill data. The base of the groundwater aquifer was discovered to be between 350 and 410 m deep. Finally, the results are reliable and closely related to earlier geological and geophysical investigations in the studied area. [ABSTRACT FROM AUTHOR]