North Eastern Desert Research Articles

Integrated petrological and geochemical studies of the Eocene carbonates from Wadi Sannur and Wadi Arhab regions, North Eastern Desert, Egypt

Integrated petrological and geochemical studies of the Eocene carbonates from Wadi Sannur and Wadi Arhab regions, North Eastern Desert, Egypt

Spectrometric and remote sensing investigations of some granitic rocks in the Egyptian north Eastern Desert: Insights on environmental radiogenic heat production

Spectrometric and remote sensing investigations of some granitic rocks in the Egyptian north Eastern Desert: Insights on environmental radiogenic heat production

Utilizing the Gamma-Ray Spectrometric and Magnetic Methods for Determining the Radioactive Anomalies and Their Relation to the Subsurface Structures, Wadi Hammad and vicinity area, North Eastern Desert, Egypt

Utilizing the Gamma-Ray Spectrometric and Magnetic Methods for Determining the Radioactive Anomalies and Their Relation to the Subsurface Structures, Wadi Hammad and vicinity area, North Eastern Desert, Egypt

The Goods and Services Offered by Native Plants from Wadi Degla Protected Area, Northeastern Desert, Egypt, A Conservation Perspective.

The Goods and Services Offered by Native Plants from Wadi Degla Protected Area, Northeastern Desert, Egypt, A Conservation Perspective.

Assessment of environmental hazard impacts in building materials (Marble), Gabal El-Galala El-Bahariya, Northeastern Desert, Egypt

Galala limestone is widely used for construction and ornamental purposes and is known throughout the world under many commercial names, including Galala White, Galala Golden, Galala Creama and Galala Classic. Using a HPGe spectrometer, about 20 samples from the marble building industry were radiometrically analyzed and the gamma radiation emitted by the radionuclides 238U, 232Th and 40K was evaluated. The measurements performed showed that the concentrations of these radionuclides were 15 ± 13, 6 ± 4 and 1100 ± 330 Bq kg−1, respectively. It's important to note that all these recorded values do not exceed the internationally reported average levels of 33, 45 and 412 Bq kg−1for each individual element. The annual effective dose (AED) was estimated. The mean value of AED, 0.07 mSv/y, is comparable to the permissible average of 0.07 mSv/y, respectively. The relationship between radionuclides and their radiological hazard characteristics was studied using various multivariate statistical techniques such as Pearson correlation, principal component analysis (PCA), and hierarchical cluster analysis (HCA). The results indicate that the main contributors to the radiological hazard associated with marble are uranium and potassium. As a result, the use of marble in building materials may not pose a significant risk to public health.

Taxonomic review, palaeoecological, and palaeobiogeographical significances of Campanian Tethyan oysters from the North Eastern Desert, Egypt

The Late Cretaceous was a time of high eustatic sea level that enabled extensive epicontinental seaways and carbonate platforms across the Tethyan Realm, providing favorable habitats for oyster communities to flourish. This study focuses on the Campanian Tethyan oysters from the North Eastern Desert of Egypt regarding taxonomy, palaeoecology, and palaeobiogeography. Three oyster species, Nicaisolopha nicaisei (Coquand, 1862), Pycnodonte (Phygraea) vesicularis (Lamarck, 1806), and Ambigostrea bretoni (Thomas and Peron, 1891), were identified from the Campanian succession in two studied sections. The sampled specimens of the genus Nicaisolopha have undergone a systematic palaeontological revision. As a result, N. tissoti (Thomas and Peron, 1891) is considered herein a junior synonym of N. nicaisei (Coquand, 1862). Palaeobiogeographically, the likely primary migration pattern of the studied oysters suggests an east–west trend along the Southern Tethys margin. All identified oysters in this study exhibit a Tethyan affinity and are primarily abundant in two main provinces: the Southern Tethys and the Western Tethys. The macrofaunal contents are categorized into two fossil associations: the Nicaisolopha nicaisei association of the middle-late Campanian age and the Pycnodonte vesicularis association of the late Campanian age. These macrofaunal associations indicate a deepening trend during the middle-late Campanian age, suggesting a transition from shallow inner neritic to middle neritic environments. Additionally, it is observed that Pycnodonteinae tend to grow larger under eutrophic conditions, low-energy environments, and nutrient-rich waters with high carbonate contents.

Structural Lineaments Detection Using Integrating Remote Sensing and Aeromagnetic Data in Gabal Umm Tinassib and its Surrounding Area, North Eastern Desert, Egypt

Structural Lineaments Detection Using Integrating Remote Sensing and Aeromagnetic Data in Gabal Umm Tinassib and its Surrounding Area, North Eastern Desert, Egypt

Space/ground-borne techniques and petrographic microscopic dissection for geologic mapping in Gabal Ras Abda area, Northeastern Desert, Egypt

BackgroundGabal Ras Abda area as a part of the Red Sea Mountain range, is characterized by inaccessible and rugged terrains. The exposed rock units are hardly followed in the field because of the rigid topography. Thus, the present work proposes and develops an integrated approach to map the exposed rock units and extract the geologic structures using satellite imagery data followed by both field and petrographic verification, saving time, efforts and cost.ResultsTo achieve the target, both the measured spectral signature curves with Landsat-8 and Sentinel-2A data were used to develop and create the most enhanced Band Ratios and Principal Components for lithological discrimination and mapping which were (((Band7 + Band 4)/(Band 7), (Band 2)/(Band 2 + Band 5) and (Band 5) in RGB) and ((Band 9 + Band 11 + Band 12)/(Band 1), (Band 4 − Band 2) and (Band 11/Band 6) + (Band 6) in RGB)) with Principal Component Bands ((PC1, PC2 and PC3 in RGB) and (PC3, PC2 and PC1 in RGB)), respectively. Also, georeferenced Google Earth Pro, panchromatic band of Landsat-8 and ALOS PALSAR Digital Elevation Model images were used to extract the structural lineaments. Geologic, petrographic and field structural studies were emphasized the remote sensing results, indicating that the main rock types cropped out in Ras Abda area from the oldest to the youngest are older granitoids (quartz-diorites, tonalites and granodiorites), Dokhan volcanics (andesites, rhyodacites, rhyolites and their related tuffs), younger gabbros, younger granites (monzogranites, syenogranites and alkali-feldspar granites), post-granite dykes and offshoots (acidic, microgranitic and basic types) and Phanerozoic sedimentary rocks. Also, the study emphasized that the E-W trend is the main structural trend controlling the investigated area followed by WNW-ESE and NE-SW directions.ConclusionsThe results of remote sensing achieved compliance with the geologic, petrographic and structural investigation through distinctly differentiating the different rocks and extracting the lineaments, indicating the accuracy of the remote sensing results and emphasizing their importance and effective role in producing a precise and highly accurate geologic map.Graphical abstract

Mineralogy and Geochemistry of Hydrothermally Altered Rocks and Gold Mineralization, at Makhrag El-Ebl area North Eastern Desert, Egypt.

Mineralogy and Geochemistry of Hydrothermally Altered Rocks and Gold Mineralization, at Makhrag El-Ebl area North Eastern Desert, Egypt.

The first Protosiren remains preserved in ornamental limestones, Middle Eocene, North Eastern Desert, Egypt

A recent revelation has come to our attention, revealing the remarkably well-preserved post-cranial remains belonging to Protosiren. These remains include vertebrae, ribs, and fragmentary bones, and were discovered from two different horizons located in the Mokattam Formation of El-Galala Plateau, North Eastern Desert of Egypt. The first specimen, GCU0101, is identified as Protosiren sp., whereas the GCU0201 specimen is recognised as Protosiren cf. P. fraasi due to certain distinguishing features. These include vertebrae with wide keyhole-shaped neural canals, reduced tuberculum on the ribs, lack of pachyostotic ribs, and the possession of rugose articular rib head. This discovery is remarkable, as it offers a unique opportunity to study the ancient marine mammal's morphology and osteology, shedding light on its evolutionary history and ecological niche. The study documents the first occurrence of Protosiren from an ornamental limestone of the Middle Eocene (Bartonian) Observatory Formation from El-Galala Plateau, Northeastern Desert, Egypt.

Geochemical characteristics, hazards impact assessment and radiogenic heat production of the alkaline rocks.

This study primarily investigates the natural radioactivity level in alkaline rocks collected from the Wadi El-Dib ring complex (WDRC) in North Eastern Desert of Egypt, and assesses potential health risks associated with their use as decorative building materials. The work was accomplished using a high-purity germanium detector as well as ICP-MS and ICP-AES techniques. The WDRC composed essentially of trachyte, quartz syenite, granite and syenite. Geochemically, these rocks contain high SiO2 and alkalis with metaluminous to slightly peraluminous features. All rocks contain high concentrations of rare earth elements (∑REEs = 109-1075ppm), with clear enrichment in light REEs compared to heavy REEs [(La/Yb)N = 8.3-25.3. Radiometrically, the concentrations of the natural radioisotopes (238U, 232Th, and 40K) in the studied rock types surpassed the worldwide average values assigned for building materials by UNSCEAR. This elevation of the radioisotope concentration values is due to the presence of supplement minerals such as monazite, zircon, allanite, and rutile. Granites exhibit the highest mean concentrations of 238U (av. 164.24 ± 14.76Bq/kg) and 232Th (av. 214.37 ± 23.33Bq/kg), while trachytes demonstrate the highest 40K (av. 1352.56 ± 65.56Bq/kg) concentrations. In contrast, syenites exhibite the lowest mean concentrations for 238U (av. 54.51 ± 6.81Bq/kg) and 232Th (av. 56.76 ± 6.25Bq/kg), while quartz syenites display the lowest mean concentration of 40K (av. 1144.78 ± 96.19Bq/kg). The radiogenic heat production (RHP) associated with U, Th, and K range between 1.41 to 9.33μW/m3, exceeding the typical crustal mean value of 0.8 to 1.2μW/m3. The radiological parameters and indices evaluating risks of the outdoor and indoor radiation doses due to the investigated rocks were assessed. The results indicated that these rocks meet globally accepted values and safety standards (approved by UNSCEAR, ICRP, and EC) for surface building materials, as well as they underscore the importance of adhering to safety protocols to safeguard workers from radiation exposure within the WDRC area. Ultimately, the data herein provide a valuable database for assessing the compatibility of geochemical data and natural radioactivity level in WDRC rocks. Additionally, it reveals that from the radiological perspective, the investigated rocks are considered safe for use as decorative construction materials.

Macrofaunal communities and microfacies analysis of the upper Campanian-Maastrichtian Sudr Formation at the Galala Plateaus, north Eastern Desert, Egypt: paleoenvironmental and paleobiogeographical implications

Macrofaunal communities and microfacies analysis of the upper Campanian-Maastrichtian Sudr Formation at the Galala Plateaus, north Eastern Desert, Egypt: paleoenvironmental and paleobiogeographical implications

Geology, Petrography and Radioactivity of the Area between Wadi Dib and Wadi Mellaha, North Eastern Desert, Egypt

Geology, Petrography and Radioactivity of the Area between Wadi Dib and Wadi Mellaha, North Eastern Desert, Egypt

Lithological, structural and hydrothermal alteration mapping utilizing remote sensing datasets: a case study of Ras Abdah- Abu Hadedah area, Northeastern Desert, Egypt

Lithological, structural and hydrothermal alteration mapping utilizing remote sensing datasets: a case study of Ras Abdah- Abu Hadedah area, Northeastern Desert, Egypt

Facies analysis, provenance and tectono-depositional evolution of the Ediacaran Hammamat molasse sediments, Umm Tawat area, North Eastern Desert, Egypt

The Ediacaran Hammamat Sediments in the Umm Tawat basin of the Egyptian North Eastern Desert are exposed with an ENE-trend, along with the Dokhan Volcanics and various phases of intrusive rocks. Different lithofacies of molasse-type deposits exist, with a debate about their tectono-depositional setting, provenance, and diagenesis versus metamorphism. In this study, we present a new insight into the facies and evolution of Umm Tawat sediments using an integrated structural, sedimentological, and mineralogical approach. Lithofacies analysis revealed their deposition in continental suites of alluvial fans, braided fluvial channels, and lacustrine environments. The sediments were derived from proximal heterogeneous sources of intermediate and acidic igneous rocks and a subordinate sedimentary provenance conveyed from uplifted basin margin hinterlands. Petrographic, SEM-EDX, and XRD data imply that the HS were affected by diagenesis to very low-grade metamorphism and local thermal metamorphism in contact with the intrusive younger granite. Carbon smears possibly derived from organic matter in shale were observed. Two reconstructed paleostress phases derived from fault slip data with the sedimentological analysis constrain the tectono-depositional evolution of the Umm Tawat molasse basin. We propose an early development of ENE-asymmetric sedimentary depocenter associated with the N–S-directed extensional strike-slip stress regime. Syn-tectonic deposition of the Hammamat Sediments occurred during this phase in three stages with variable sediment provenance and accommodation/sediment influx ratios. This phase was accompanied by the three phases of younger granites and the Dokhan volcanics. Positive inversion with N–S-directed compressional strike-slip stress regime caused ENE-to NE-folding and reverse reactivation for the pre-existing ENE-trending dextral faults. Up on the regional correlation, the Ediacaran Umm Tawat molasse basin differs somewhat from other molasse basins in the central Eastern Desert regarding their facies and tectono-depositional model. This basin probably formed as a continental intra-arc basin located in the northern region of the Nubian Shield.

Geology, Petrography, and Geochemistry of Younger Granites and Related Radioactive Pegmatite from Gabal El Urf Area, North Eastern Desert, Egypt: Implications for the Evolution of the NYF-Type Rare-Elements Granitic Pegmatite

Gabal El Urf region is located in the northern Egyptian Eastern Desert and overlain essentially by older and younger granitoids of Late Proterozoic age. These granitoids contain numerous outcrops of pegmatites, mostly occurring as dikes and veins or huge separated masses. In the contrary, pegmatites form lens-like bodies enclosed within the younger granites along their margins. Previous radiometric surveys showed anomalous concentrations of radioactivity on pegmatite body, located to the south of the study region. The younger granites and the associated radioactive pegmatite are studied in details with the aim to describe this pegmatite, petrogenesis and its relation with the encolsing granite. The younger granites are monzogranite and syenogranite according to mineralogical and chemical classification. Petrographically, the two younger granitic phases are strikingly similar. Both consist of potash feldspar, plagioclase and biotite with some hornblende in the earlier phase. Gabal El Urf younger granites are categorized as highly fractionated I-type granites with metaluminous to mildly peraluminous characters, which emplaced at 600 ± 11 Ma in post-collisional environment. The radioactive pegmatite is located within the syenogranite and enriched with Zr, Nb, Ta, Y, Th, U and REEs; accordingly it was classified as NYF-type rare-elements pegmatite. Metal-bearing generations of minerals within the rare-elements pegmatite include zircon, uranothorite, betafite, aeschynite, fluorite, pyrite and ilmenite.

Late Paleocene–Early Eocene larger foraminifera from the Galala Plateaus, North Eastern Desert, Egypt: biostratigraphic, paleoenvironmental and paleoecological implications

Two stratigraphic sections are investigated, and a diverse larger benthic foraminiferal assemblage is recorded from the upper Paleocene–lower Eocene Southern Galala Formation at the Galala Plateaus, north Eastern Desert, Egypt. Twenty-eight larger foraminiferal species, belonging to thirteen genera, are identified and their comparative stratigraphic range with the Tethyan zonations of Hottinger (1960) and Serra-Kiel et al. (1998) is documented. Nine shallow benthic zones (SBZ3-6 and SBZ8-12) are designated in the studied interval, involving index zonal markers, e.g., Glomalveolina primaeva (Reichel), G. levis Hottinger, Nummulites atacicus (Leymerie), Alveolina vredenburgi Davies, and A. ellipsoidalis Schwager. Fifty-four thin sections are prepared and analyzed, yielding seven microfacies types in the present study, with larger benthic foraminifera as the dominant biotic components. These microfacies types indicate a deposition in restricted tidal flat inner ramp to open-marine middle ramp environments. The inner ramp environments are dominated by alveolinids, orbitolitids, and in part by miliolids and orthophragminids, reflecting euphotic to mesophotic, meso-oligotrophic, and normal to hyper salinity conditions. The middle ramp environment is characterized by nummulitids, implying meso-oligophotic, oligotrophic, and normal salinity conditions. The studied successions at the Galala Plateaus are devoid of corals in platform stages II and III, similar to the Pyrenean strata from middle latitudes at the northern Tethys, except for small coral patches in both stages in the latter due to the cooler temperature. The Early Eocene (Cuisian) Nummulites accumulations suggest a development on paleohighs in a distal inner ramp environment, and then a transportation by wave and current actions into the surrounding proximal middle ramp environment.

Late Cenomanian–early Turonian ammonite successions of north Eastern Desert, Egypt: biostratigraphy and paleobiogeographic implications

The upper Cenomanian-lower Turonian sequence of Egypt yield a remarkably diverse and plentiful ammonite fauna. Three stratigraphic sections located on Wadi Araba, north of the Southern Galal Plateau were investigated. Lithostratigraphically, the measured sections are subdivided from base to top into the Malha (pre-Cenomanian), Galala (Cenomanian) and Maghra El Hadida (Turonian) formations. Over a hundred well-preserved and nearly complete ammonite internal molds were collected. The studied ammonites are systematically classified as Vascoceratidae, Pseudotissotiidae, Acanthoceratidae and Engonoceratidae. Vascoceratidae and Pseudotissotiidae comprise 75% of the identified ammonites. Twelve ammonite species have been identified. Six late Cenomanian-early Turonian ammonite biozones are proposed herein: Neolobites vibrayeanus, Vascoceras gamai, Vascoceras cauvini, Vascoceras proprium, Choffaticeras segne, and Wrightoceras munieri. The identified ammonite biozones are correlated with NW European standard zonation and the Tethyan biostratigraphical schemes was performed. The first occurrences of Vascoceras proprium, as well as the first occurrences of the inoceramids Mytiloides kosmati and Mytiloides puebloensis define the Cenomanian-Turonian boundary. The diversity and abundance of studied fossil groups varied dramatically over the C/T transition. In the latest Cenomanian, all identified Cenomanian species had become extinct. Only three species have reached the Turonian time. The paleobiogeographic implications of the descried ammonites are thoroughly discussed. The paleogeographic distribution of the studied ammonite fauna shows that the majority of the described species are restricted to the shallow shelf of the southern Tethys.

Upper Cretaceous (Coniacian-Santonian) low diversity oyster-dominated macrofaunal association in the Eastern Desert of Egypt: Taphonomy versus ecology

In contrast to the Cenomanian-Turonian, the Coniacian-Santonian macroinvertebrates of the Middle East and North Africa are rarely investigated. Previous investigations indicated the occurrence of low diversity faunal associations, which can be attributed either to ecological (primary/biogenic) or taphonomic (secondary/sedimentologic) factors. The poorly preserved macrofauna of the Hawashia Formation (north Eastern Desert, Egypt) has been quantitively analyzed resulting in the identification of fifteen macrofaunal species including five bivalve, seven gastropod, two ammonite taxa, and one echinoid taxon. The occurrence of the ammonites Metatissotia fourneli Bayle and Texanites (T.) texanus Roemer confirm the Coniacian‒Santonian age for the Hawashia Formation. Based on litho- and biofacies, this fauna likely lived in a normal oxygen tidal-influenced shallow subtidal environment under arid conditions. Taphofacies indicates a low-energy regime with low sedimentation rate. Most shells are highly damaged (encrusted, bioeroded, and fragmented) due to their long residence time in the Taphonomic Active Zone (TAZ). Few of the benthic species have a wide geographic distribution (e.g., Oscillopha dichotoma), which generally imply low sea-level. In contrast, ammonites have been precariously recorded from Africa, Europe, and Asia in addition to South America, outlines a cosmopolitan attitude.

Au-Cu Resources in Some Mines from Antiquity in the South Gabal Um Monqul and Gabal Al Kharaza Prospects, North Eastern Desert, Egypt

Since Antiquity, sustainable resources of gold and copper have been mined at two prominent prospects in the north Eastern Desert of Egypt, namely the south Gabel Um Monqul (SGUM) and Gabal Al Kharaza (GKZ). Mineralization is hosted by Neoproterozoic shield rocks represented by dacite and monzo- to syenogranite at the SGUM prospect whereas they are diorite, granodiorite, and quartz feldspar porphyry at the GKZ prospect. These hosts have been emplaced in an island arc environment from calc-alkaline magmas with a peraluminous to metaluminous signature. They are hydrothermally altered including albitization, sericitization, silicification, epidotization, and chloritization. The Au and Cu mineralizations are confined to shear zones that lately filled with auriferous quartz veins adjacent to mineralized alteration zones. In the GKZ prospect, the old trenches trend mainly in a NW–SE direction whereas it is NE–SW and NW–SE in the SGUM prospect. Evidence of shearing ranges from megascopic conjugate fractures and shear planes in the outcrops to microscopic sheared and crumbled Au-Cu ore assemblages dominated by Fe-Cu sulfides, specularite, and barite. Microscopic investigation suggests that the formation of specularite is due to the shearing of early existing magnetite. The ore textures and paragenetic sequence indicate that pyrite in the alteration zones is oxidized, leading to the liberation of gold up to 3.3 g/t. The formulae of the analyzed electrum lie in the range Au74.5-76.8 Ag22.2-24.5. Integration of the field, geochemistry, and mineral chemistry data, combined with the gold fire assay data prove the presence of sustainable amounts of disseminated Au and Cu, not only in the mineralized quartz veins, but also in the alteration zones. Data materialized in our paper show similarities in the style of mineralization at the SGUM and the GKZ prospects with iron oxide-copper-gold (IOCG) deposits elsewhere in the Arabian-Nubian Shield (ANS) and other world examples.