Geology and geochemistry of Tertiary basalt in south Wadi Hodein area, South Eastern Desert, Egypt

Shahin, Hassan A. A.; Masoud, Masoud S.

doi:10.1007/s12517-012-0525-6

Cited by 6 publications

(2 citation statements)

References 14 publications

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“…1c due to the presence of extrusive basalt cover on top of Jebel-Qatrani (Jebel-Qatrani can be translated from Arabic as Tar Hills). This basalt occurs in several localities all over Egypt, mainly at Gabal Qtrani, Cairo-Suez District, south Quseir, Abu Zaabal, Baharyia Oasis, East Samalut, and south Wadi Hodein and is considered the youngest unit in the basement rocks in Egypt (Shahin and Masoud, 2013).…”

Section: Geologic Setting Of the Areamentioning

confidence: 99%

Detection of subsurface basaltic sheets and associated structures utilising forward modelling and inversion of 2D electrical resistivity data: A case study from Jebel-Qatrani, Fayoum, Egypt

EL HAMEEDY,

MABROUK,

DAHROUG

et al. 2023

Contrib. Geophys. Geod.

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In the north of Fayoum Governate, Egypt, numerous extrusive flows of basalt rocks exposed on the surface and affected by weathering and erosion, forming altered basalt sheets which is the case of the Jebel-Qatrani. The study objective comes in two main folds: the first, to choose the optimum parameters required for the filed survey by generating forward models using several arrays with 3% Gaussian random noise, simulating the geology of the study area deploying a finite element modelling approach; the second, to acquire the real field data and generate the electrical resistivity tomograms to ascertain the existence, extension, and characteristics of the basaltic sheets in the subsurface. Hence, four electrical resistivity profiles with a Wenner-alpha array with 48 electrodes, 5 metre electrode spacing, and a total length of 235 metres were acquired in suitable locations based on previous aeromagnetic results in the vicinity of the study area. These profiles were inverted to derive the true resistivity distribution of the subsurface. Another objective is to detect the near-surface, Oligocene normal faulting structures associated with rifting of the Red Sea. Results from two inverted resistivity tomograms show a possible normal fault cutting through the early Oligocene Qatrani Formation at the same time as red sea rifting, confirming previous geological studies in the Fayoum region based on satellite imagery, aeromagnetic data, and geological outcrops. It is concluded that near these faults, a sheet-like body of relatively high resistivity values, representing basaltic extrusions, was detected, confirming that the basaltic presence is associated with these structural zones.

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Section: Geologic Setting Of the Areamentioning

confidence: 99%

Detection of subsurface basaltic sheets and associated structures utilising forward modelling and inversion of 2D electrical resistivity data: A case study from Jebel-Qatrani, Fayoum, Egypt

EL HAMEEDY,

MABROUK,

DAHROUG

et al. 2023

Contrib. Geophys. Geod.

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“…Their alkalis and SiO 2 overlap those from west Dalaga (Abdel Aal et al, ) and are distinct compared with the other Egyptian basalts (Figure a). Based on the TiO 2 contents, these rocks can be classified as high‐Ti basalts (TiO 2 > 2.5 wt.%) comparable with CED and NE Egypt basalts (Endress, ; Farahat et al, ) but are discrete compared with south Eastern Desert (Shahin & Masoud, ). They display sodic character (Na 2 O/K 2 O = 2.47–2.93).…”

Section: Bulk‐rock Geochemistrymentioning

confidence: 99%

Origin and geotectonic evolution of Mir Tertiary basaltic andesite dykes, Western Desert, Egypt: Constraints from mineral and bulk‐rock chemistry

Farahat

Ali

2018

Geological Journal

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Compared with widespread Egyptian Tertiary basaltic rocks, Mir Tertiary basaltic dykes from the Western Desert of Egypt show distinct mineralogical and geochemical characteristics that provide insights into the nature of their mantle source and geotectonic evolution as well as melting and crystallization conditions. Their mineralogical features (i.e., presence of orthopyroxene and lack of olivine) distinguish them from the other Egyptian Tertiary basalts. They have basaltic andesite compositions (SiO2 = 53.55–55 wt.%, Na2O + K2O = 4.64–4.8 wt.%, MgO = 2.66–3.02 wt.%) with tholeiitic character. Temperature of crystallization ranges from 1,112°C to 1,140°C for plagioclase; from 1,085°C to 1,123°C for clinopyroxene; and from 1,034°C to 1,090°C for orthopyroxene. These results are in harmony with petrographic observations which suggest early crystallization of plagioclase, followed by simultaneous crystallization of plagioclase and clinopyroxene, and soon thereafter by orthopyroxene crystallization. Titanomagnetite–ilmenite intergrowths indicate oxygen fugacity (ƒO2) of −12.09 and −9.4 log units, suggesting crystallization at relatively oxidized conditions. Their temperature ranges from 959°C to 1,125°C, suggesting that the titanomagnetite joins the crystallized phases at early stages and continued until later stages. Mir basaltic andesite (MBA) has low Ni (15–27.9 ppm), Cr (19.8–48.5 ppm), and Sc (20–25 ppm) concentrations together with high FeOt/MgO ratios (3.18–3.58) relative to primitive basalts, arguing for their evolved nature. They have sub‐chondritic Nb/Ta ratios (15.5–17) similar to ocean–island basalts and higher than those of continental crust, ruling out a significant effect of crustal contamination. The high La/Nb (>1.4) with the negative Nb, Ta, and Ti anomalies on the primitive mantle‐normalized patterns most likely indicates that their primary magma was derived from partial melting of a mantle source previously metasomatized by influx of subduction‐related slab fluids/melts. Moreover, the super‐chondritic Zr/Hf ratios (39.55–55.21) and the negative K and Ti anomalies point to carbonate metasomatism of their mantle source. This inference is further supported by their high (K2O + Na2O)/TiO2 ratios (>1) which are comparable with experimentally produced carbonated peridotite melts. The high Zr/Y (average 9.75) and La/Yb ratios (8.6–10) of the MBA suggest that they were generated via low degrees of partial melting. Indeed, modelling calculations indicate generation by lower melting degrees (<10%) of a garnet‐bearing lherzolite mantle source. The melting region was at the garnet stability field suggesting a deeper origin (exceeds ~85 km) for MBA. Field and geochemical characteristics of the Egyptian Tertiary volcanism proved that it is spatially and temporally related to extension that has occurred during Red Sea rifting. Extension most likely due to the NE–SW tensional stresses which reactivated the old fractures and triggered mafic magma generation through passive upwelling of the asthenospheric mantle.

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Phanerozoic Minor Volcanics and Intrusives of the Arabian-Nubian Shield

Saleh

Kamar

Mira

2021

Regional Geology Reviews

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Geology and geochemistry of Tertiary basalt in south Wadi Hodein area, South Eastern Desert, Egypt

Cited by 6 publications

References 14 publications

Detection of subsurface basaltic sheets and associated structures utilising forward modelling and inversion of 2D electrical resistivity data: A case study from Jebel-Qatrani, Fayoum, Egypt

Detection of subsurface basaltic sheets and associated structures utilising forward modelling and inversion of 2D electrical resistivity data: A case study from Jebel-Qatrani, Fayoum, Egypt

Origin and geotectonic evolution of Mir Tertiary basaltic andesite dykes, Western Desert, Egypt: Constraints from mineral and bulk‐rock chemistry

Phanerozoic Minor Volcanics and Intrusives of the Arabian-Nubian Shield

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