East Sinai Research Articles

Integrated study of groundwater aquifers and productive wells for sustainable development in El-Kharrouba area North East Sinai Peninsula, Egypt

Integrated study of groundwater aquifers and productive wells for sustainable development in El-Kharrouba area North East Sinai Peninsula, Egypt

Metamorphic conditions and igneous activity in the Um Zariq area, East Sinai, Egypt: Mineralogical and petrological evidences for the transformation from collisional to an extensional regime in the Arabian-Nubian shield

The authors present new petrographic and mineralogical data for the Um Zariq Formation which belongs to Arabian–Nubian Shield metamorphic exposures in the Sinai Peninsula. The formation is believed to be a metasedimentary sequence whose protolith was deposited during the Sturtian Snowball Earth Event (SEE). Our new field data indicate the occurrence of metasomatised limestones/dolostones (calc-silicates) which is distinct from those reported from The Feiran-Solaf Metamorphic Complex. We highlight the presence of a lamprophyre body close to the Kid A-type granite; the Malhaq vogesite - a variety of hornblende-phyric lamprophyre with orthoclase feldspar-. Based on mineral assemblages, field observations and petrographic study, metapelites record an early greenschist/lower amphibolite facies regional metamorphism. Intrusion of the syn-collisional deformed granites (CA1) synchronised with the regional metamorphism at ca. 660±25 Ma. Both of the metamorphic events overprinted on the metapelites and calc-silicates. The contact metamorphism formed cordierite and andalusite in the metapelites and pyroxenes in the calc-silicates. Calc-silicates, on the other hand, record anisotropic fabrics, higher T metamorphic mineral assemblages with hornfelsic texture. The Um Zariq metapelites protoliths were deposited at a deeper stratigraphic level and thus, recorded the regional and contact metamorphism contrary to the shallower carbonates. The peak metamorphic conditions were followed by retrograde metamorphism marked by chlorite and prehnite from metapelites and prehnite, epidote and chlorite in calc-silicates. The Um Zariq igneous activity (Kid A-type Granite and the Malhaq Lamprophyre) marks the transformation from collisional to extensional regime in the Arabian–Nubian Shield at ca. 600 Ma.

Integrated geophysical investigation for mapping of manganese-iron deposits at Wadi Al Sahu area, Sinai, Egypt—a case study

This study used data from an investigation into the mapping of manganese-iron (Mn-Fe) mineralization, located within the Um Bogma formation. The ore takes the form of patchy isolated bodies or lenses in the three members of the Um Bogma formation located in East Sinai, Egypt. Magnetic, resistivity, and induced polarization (IP) surveys were applied at the Wadi Al Sahu area to delineate the mineralized ore bodies in terms of depth and extension. The quantitative interpretation of magnetic data was carried out using the 2D analytical signal. The results of the magnetic interpretation indicated that the depths of such ore deposits range from − 2 to − 20 m, and the shape of the magnetized units (assumed to be manganese-iron ore) is lenticular and of small size ranging from 20 to 100 m in width. Three dipole-dipole geo-electrical traverses were carried out along the anomalous sites, the traverse locations selected from the constructed magnetic maps of the study area, and the resistivity and IP measurements along with them. The results of the resistivity and IP inversion indicate that there are conductive and chargeable bodies at a depth that indicate the shape of small Mn-Fe lenses being present and conform to the shape of the Mn-Fe ore mineralization. Integration between the magnetic and geo-electrical data is made to lessen the non-uniqueness problem in geophysical prospecting. In this case, we used electrical resistivity and induced polarization models to delineate the boundaries between different geo-electric units, and these boundaries were used as interfaces between layers with different magnetic susceptibility for magnetic modeling to perform magnetic data inversions.

Geophysical and hydrogeochemical investigations of Nubian sandstone aquifer, South East Sinai, Egypt: Evaluation of groundwater distribution and quality in arid region

The expansion in human activities, the absence of running water in South Sinai province in northeastern Egypt and the high cost of seawater desalination render groundwater the essential source for potable water in this arid region. This contribution represents the integration of geophysical and hydrochemical investigations to delineate groundwater distribution and evaluate the water quality of the Cretaceous sandstone aquifer of Wadi Barqa area, Southeastern Sinai. The locations of sites, suitable for geophysical sounding measurements, were selected using digital elevation map. Vertical electrical sounding (VES) and time-domain electromagnetic sounding (TEM) measurements were carried out to determine the depth and thickness of the unsaturated and water-saturated zones as well as the groundwater quality, which were verified by calibrating the estimated electrical resistivity values with the design and logs data of eleven drilled wells next to the sites of geophysical soundings. The VES and TEM data revealed the presence of relatively thick zoned aquifer, overlain by unsaturated zone with variable thickness (83-65 m). The upper aquifer zone (25–43 m thick) is characterized by higher resistivity values (16–163 Ohm.m), reflecting fresh water signature, whereas the lower aquifer zone (122–150 m thick) has lower resistivity values (16–24 Ohm.m), indicating saturation with semi-fresh to relatively brackish water. Water samples, collected from wells taping the Nubian Sandstone aquifer, have average total dissolved solids (TDS) value of 544 mg/l. The hydrochemical parameters of these samples are consistent with NaCl water type with the majority of samples belonging to high salinity with low sodium categories. This suggests that the groundwater of the aquifer was dominated by old meteoric origin. The compositional characteristics of the groundwater of the investigated aquifer indicate suitability for domestic and irrigation purposes. However, due to the arid nature of Southeastern Sinai province, it is recommended to use this groundwater as potable water.

Tectonic evolution of kid metamorphic complex and the recognition of Najd fault system in South East Sinai, Egypt

A low-to medium-grade metamorphic belt of a volcano-sedimentary succession occurs in the eastern side of South Sinai as a part of the northernmost extension of the Arabian–Nubian Shield in Egypt. The belt is known as the Kid metamorphic complex. It is considered as one of the major belt among the other exposed metamorphic belts in South Sinai. Here, we detect and investigate the signature of the Najd Fault system in South Sinai based on detailed structural analysis in field and digital image processing. The enhanced satellite image and the geo-spatial distributions confirm that the Kid belt is essentially composed of nine Precambrian units. Field relations and geometrical analysis of the measured structural data revealed that the study area underwent four successive deformational phases (D1–D4). D1 is an upright tight to isoclinal large-scale folds that caused few F1 small-scale folds and a steeply dipping S1 axial plane foliation. The second deformational event D2 produced dominant of sub-horizontal S2 foliation planes accompanied with recumbent isoclinal folds and NW–SE trending L2 lineations. The main sense during D2 was top-to-the-NW with local reversals to the SE. The third folding generations F3 is recorded as axial plane S3-surfaces and is characterized by open concentric folding that overprinting both F1 and F2 folds and has a flexural-slip mechanism. F3 fold hinges plunge to the west–northwest or east–southeast indicate north–northeast–south–southwest shortening during D3. The fourth deformational event D4 is characterized by NE plunging open concentric folding overprint the pre-existing fold generations and formed under flexural slip mechanism reflecting coaxial deformation and indicating change in the stress regime as a result of the change in shortening from NE–SW to NW–SE. This phase is probably accompanied with the final assembly of east and west Gondwana. The dextral NW–SE shear zone that bounded the southwestern portion of the metamorphic belt is probably related to reactivation of the Najd fault system during Oligo-Miocene in South Sinai.

Petrography and geochemistry of the siliciclastic Araba Formation (Cambrian), east Sinai, Egypt: implications for provenance, tectonic setting and source weathering

AbstractCombined petrographic and geochemical methods are utilized to investigate the provenance, tectonic setting, palaeo-weathering and climatic conditions of the Cambrian Araba clastic sediments of NE Egypt. The ~ 60 m thick Araba Formation consists predominantly of sandstone and mudstone interbedded with conglomerate. Petrographically the Araba sandstones are mostly sub-mature and classified as subarkoses with an average framework composition of Q80F14L6. The framework components are dominated by monocrystalline quartz with subordinate K-feldspar, together with volcanic and granitic rock fragments. XRD analysis demonstrated that clay minerals comprise mixed-layer illite/smectite (I/S), illite and smectite, with minor kaolinite. Diagenetic features of the sandstone include mechanical infiltration of clay, mechanical and chemical compaction, cementation, dissolution and replacement of feldspars by carbonate cements and clays. The modal composition and geochemical parameters (e.g. Cr/V, Y/Ni, Th/Co and Cr/Th ratios) of the sandstones and mudstones indicate that they were derived from felsic source rocks, probably from the crystalline basement of the northern fringe of the Arabian–Nubian Shield. The study reveals a collisional tectonic setting for the sediments of the Araba Formation. Palaeo-weathering indices such as the chemical index of alteration (CIA), chemical index of weathering (CIW) and plagioclase index of alteration (PIA) of the clastic sediments suggest that the source area was moderately chemically weathered. On the northern margin of Gondwana, early Palaeozoic weathering occurred under fluctuating climatic conditions.

Provenance and Source Area Weathering Derived from the Geochemistry of Pre-Cenomanian Sandstones, East Sinai, Egypt

Provenance and Source Area Weathering Derived from the Geochemistry of Pre-Cenomanian Sandstones, East Sinai, Egypt

Petrography and geochemistry of lower Paleozoic sandstones, East Sinai, Egypt: Implications for provenance and tectonic setting

Petrography, mineralogy and chemical analyses were combined to investigate the lower Paleozoic sandstones at Wadi El-Quseiyeb area, East Sinai. They are mainly classified texturally as silty sandstones, sandstones and clayey siltstone. Their average modal composition (QFL, 87:11:2), classifies them as quartz arenite and arkosic arenite, with high proportions of quartz, monocrystalline quartz grains, more potash feldspar than plagioclase and a low plagioclase/total feldspar ratio ( P/ F < 0.2). High SiO 2, K 2O > Na 2O, and low Fe 2O 3 + MgO values revealed by chemical analyses are consistent with the modal data. Other criteria include elevated Ba and Sr contents and depletion in the ferromagnesian elements. The petrography and geochemistry suggest a stable continental (passive) margin or intracratonic basin, analogous to that of an Atlantic-type continental shelf. Also, they reflect a stable craton interior source, devoid, to a large extent, of basic debris and ultimately derived from a low-lying granite-rich Precambrian craton. Chemical index of alteration (CIA) and the Plagioclase index of Alteration (PIA) values range from 57.2 to 93.0 and from 79.7 to 94.6, respectively. However, most samples have values more than 60, suggesting a moderate to relatively high degree of alteration (weathering) in the source area.

Gamma-ray spectrometry: a new tool for exploring archaeological sites; a case study from East Sinai, Egypt

In geophysical literature the application of gamma-ray spectrometric (GRS) methods in archaeological exploration is not known. This paper demonstrates the applicability of the GRS technique to archaeological exploration. The study was conducted in the Tell Abu Seef area, which is located ∼6 km from El-Qantara city, Egypt where some buried walls (of possible archaeological interest) were detected in 1981. The recorded K% values as well as the readings of total gamma-ray intensities were related to two different radiometric areas that match the building remains and the surrounding sediments. The highest concentrations of K% coincide with the wall remains, which consist of muddy material. Lower values of K% were found in the surrounding media, which consists of Quaternary sediments. The contrast between the building remains and the surrounding sediments is so clear that it is obvious that GRS is capable of offering solutions to important archaeological problems.

Depositional facies of the Cambrian Araba Formation in the Taba region, east Sinai, Egypt

A thick succession of Cambrian sediments is exposed in the Taba region, east Sinai, and subdivided into the Araba Formation and the overlying Naqus Formation. The vertical and lateral distribution of the Araba Formation in the Taba region provides an outstanding example of an overall retrograding sequence. Three distinctive units (I, II and III) are distinguished within this succession on the basis of depositional geometries, stratified patterns, sedimentary features and petrographic examinations. They record different depositional environments and each unit is distinguished by a particular facies association, which records processes characteristic of these environments. The lower unit (I) is dominated by five depositional facies (la-le) which belong to low sinuosity braided channels associated with floodplain fines and alluvial fans. Channel deposits are represented by tabular cross-bedded and horizontally stratified pebbly coarse-grained sandstones. The middle unit (II) reveals a relative sea level rise and is composed of fine- to coarse-grained sandstone, shale and mudstone with carbonate intercalcations. From four depositional facies (Ila-Ild), recognised facies (Ila, Ilc and Ild) are comparable to upper-lower shoreface and tidal channel environments. The fourth facies (Ilb) is carbonate-dominated with trilobite tracks, and reflects deposition in the upper-middle intertidal flat. The latter facies (llb) is subjected to intea-Cambrian karstification, which is deduced from the presence of macro- and microscopic fresh water calcite fillings, botryoidal Fe and Mn oxides and terra rossa. The uppermost unit (III) is shale-dominated from the inner shelf and is represented by two facies (Illa and Illb). Despite the general rise in sea-level in the Araba Formation, the uppermost facies (Illb) points to a progradational-upward tendency in unit (III), and this is coeval with an increase in the percentage of interbedded fine-grained sandstones.

Late Maastrichtian litho- and ecocycles from hemipelagic deposits of eastern Sinai, Egypt

A biostratigraphical and palaeoecological survey employing calcareous nannofossils and planktonic and benthonic foraminifera has been carried out in four sections of hemipelagic marls and chalks of the Late Maastrichtian Abathomphalus mayaroensis Zone of eastern Sinai, in order to evaluate the mechanisms controlling the composition of the well preserved microfauna and nannoflora. The Abathomphalus mayaroensis Zone in eastern Sinai can be easily identified by the wide occurrence of the index fossil A. mayaroensis and can be further subdivided by the first occurrences of Plummerita reicheli (ex. P. hantkeninoides) and Micula prinsii. Microfossil abundances and lithologies are characterised by pronounced repetitive distribution patterns. These include low and high frequency fluctuations of the planktonic/benthonic (P/B) foraminiferal ratio, repetitive changes in the abundance of calcareous nannofossils and benthonic foraminifera, as well as the development of chalk-marl couplets and thinning upward chalk packets. both microfossil distribution patterns and the occurrence of rhythmites are attributed to changes in primary palaeoproductivity. Semiquantitative investigations of calcareous nannofossils and a few selected benthonic foraminifera yield evidence of the presence of high (HP) and low (LP) productivity assemblages. The interpreted HP assemblage is dominated by Glaukolithus diplogrammus, Manvitella pemmatoidea, Microrhabdulus decoratus and Micula murus and the benthonic foraminifera Neoflabellina jarvisi; the LP assemblage is characterised by Lithraphidites quadratus and Bolivinoides draco. However, further quantitative studies are necessary to reconstruct the exact composition of these assemblages and to explain deviatory developments. The chalk-marl couplets, thinning-upward chalk packets and the high frequency P/B patterns are interpreted to reflect productivity changes related to orbital forcing. These hemipelagites were deposited during the latest phase of the southern Tethyan upwelling system, which was active from the Santonian to the Late Maastrichtian with a peak in the Campanian. Termination of upwelling just before the K/T boundary also provides a good explanation for the change towards a palaeobathymetric control on foraminiferal distribution, as observed for the Palaeocene of central east Sinai.

Paleostress determination in a rock by a fractographic method

A fractographic technique, hitherto used in ceramics for the evaluation of fracture stress, is adapted here to calculate fracture paleostresses in rocks. An example from a granite in East Sinai is analyzed. The results obtained for the ranges of local paleofracture stress, the severest flaw size and the initial stress intensity factor agree reasonably well with previous evaluations of fracture stresses in granite and with direct observations of the rock's grain size.

Plant Studies in Syria

IN the scientific world, Syria is gaining prominence chiefly with several, important botanical studies made by the botanists of the Hebrew University at Jerusalem, where a representative Syrian collection has been compiled in the Herbarium, and by several expeditions of naturalists in the British Army who have collected specimens of fauna and flora for the British Museum under an Army organization known as the Middle East Biological Scheme. There are four great deserts in the Middle or Near East Sinai, Negeb (Palestine), Judea and the adjacent Ghor (the 'Avrah), southern Iraq and the Syrian desert (which includes part of Transjordania) – available for investigation.