Lithostratigraphic and sedimentary evolution of the Kom Ombo (Garara) sub-basin, southern Egypt
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ORIGINAL PAPER
Lithostratigraphic and sedimentary evolution of the Kom Ombo (Garara) sub-basin, southern Egypt B. Issawi 1 & E. Sallam 2 & S. R. Zaki 1
Received: 19 October 2015 / Accepted: 15 March 2016 # Saudi Society for Geosciences 2016
Abstract Southern Egypt is mostly covered by clastic sediments belonging to the Paleozoic and the Mesozoic. The Precambrian basement rocks bound the Etbai area to the east and Gabgaba area to the west. The basement extends further west forming dissected small and major exposures in southern Egypt, south of latitude 23° 30′ N but are covered by Cretaceous-Lower Tertiary sediments further north, the Western Limestone Plateau. The clastic sediments in southeast Egypt, on the western side of the basement rocks in-between latitudes 22° N and 24° 35′ N, built two sub-basins, Kom Ombo (Garara) sub-basin in the north and south Nile Valley sub-basin in the south. These are separated by a dissected basement wall. The two sub-basins have different lithostratigraphic successions, Paleozoic (Early to Late) in the south Nile Valley sub-basin whereas Late PaleozoicMesozoic-Tertairy in the Kom Ombo sub-basin. The platform clastic sediments within both sub-basins were possibly supplied from an easterly located Paleotethys extending to North Gondwana. The Oxfordian opening of the Indian Ocean associated with rise in sea level supplied more waters to the north and sediments by passed the filled southern Nile Valley subbasin and reached the adjacent Kom Ombo sub-basin defining a depositional shift. On the other hand, during the Jurassic, Northern Egypt received Neotethys waters that filled deeper sub-basins (e.g., the Maghara sub-basin), hence the difference in lithology between Jurassic northern and southern
* E. Sallam [email protected]
1
Geological Survey of Egypt, Cairo, Egypt
2
Department of Geology, Faculty of Science, Benha University, Banha, Egypt
sediments. Since the Jurassic, most of Egypt received Tethys waters. In the drilled wells studied, the younger top sediments surrounding the well sites are related to the Tethys geostratigraphy. The sub-basins in southern Egypt are controlled by N-S faults defining constant subsiding basins. The E-W Guinea–Nubia Lineament bounds the northern side of the Kom Ombo sub-basin, where it is closed by a northern basement arch. Keywords Lithostratigraphy . Correlation . Basin evolution . Kom Ombo-3 well . Nugra-1 well . Kharit-1 well . Southern Egypt
Introduction Historical review The clastic section in southern Egypt (south of latitude 25°N) has been a matter of great debates, for nearly a century. In the southwest of Egypt, the Gilf Kebir Plateau and its surroundings were inaccessible and immapped for a long period of time. It is only since before World War II that British interest in the area became obvious for military reasons; the Italians occupied Libya since 1911. Their interest in southeast Libya increased in the 30s of the last century. The pioneering works of Ball in Kharga Oasis (1900), in Gebel Garra and the Oasis of Kurkur (1902),
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