Emad S. Sallam

Stratigraphy, facies analysis and sequence stratigraphy of the Eocene succession in the Shabrawet area (north Eastern Desert, Egypt): an example for a tectonically influenced inner ramp carbonate platform

The Eocene rocks in the Shabrawet area (north Eastern Desert, Egypt) have been subdivided into three formations that are from base to top: the Minia Formation (Late Ypresian), the Sannor Formation (Bartonian) and the Maadi Formation (Priabonian). These three formations are disconformable with each other. In addition, the whole Eocene succession is disconformably overlain by the Oligocene rocks and is underlain by the Cretaceous rocks with an angular unconformity surface. The Sannor Formation has been subdivided into three informal units: lower, middle and upper units. The overall sedimentary nature of the Eocene rocks in the study area is dominated by carbonate-siliciclastic rocks. Detailed microfacies analysis has enabled discrimination of 22 sedimentary microfacies types, which are grouped into six facies associations, equivalent to six depositional environments sited on an inner ramp setting. These depositional environments are floodplain-dominated fluvial, lacustrine/palustrine, tidal flat, restricted inner lagoon, shoal bar and outer lagoon with open circulation. A suitable depositional model of the Eocene rocks is given. In addition, four discrete benthonic foraminiferal biozones were reported in the Eocene succession, arranged from base to top: (1) Alveolina frumentiformis biozone (Late Ypresian), (2) Orthoplecta clavata biozone (Bartonian), (3) Dictyoconus aegyptiensis biozone (Bartonian) and (4) Discorbis vesicularis biozone (Priabonian). In terms of sequence stratigraphy, the studied Eocene succession exhibits three superimposed depositional sequences, each of which shows retrogradational (transgressive systems tract) and aggradational (highstand systems tract) to progradational (lowstand systems tract) packages of facies. The retrogradational package displays a predominance of outer lagoon and restricted inner lagoon facies. The aggradational package shows an increase of shoal bar and tidal flat facies, whereas the progradational package marks the occurrence of continental facies (floodplain-dominated fluvial and lacustrine deposits). In this study, it is noticed that there are lateral and vertical changes in the depositional environments of the Eocene rocks, between shallow marine and continental environments. Also, many unconformities have been recorded in between and within these rock units. Such remarks indicate that the Eocene rocks were deposited within a highly tectonically active area that was consequently influenced by the transgression and regression of the Neo-Tethys. Such tectonic activity could be related to the Syrian Arc System that was renewed and enlarged several times during the Late Cretaceous up to the Neogene in the eastern and southeastern Mediterranean domain.

Lithostratigraphic and sedimentary evolution of the Kom Ombo (Garara) sub-basin, southern Egypt

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 Paleozoic-Mesozoic-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 sub-basin 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 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.

Analysis and bioequivalency study on two tablet formulations of co–trimoxazole

This paper describes an analytical procedure for simultaneous quantification of trimethoprim (TMP) and sulphamethoxazole (SMZ) in serum. Serum samples were rendered alkaline with glycinesodium hydroxide buffer.(pH 9–1) and extracted with ethyl acetate. The reconstituted sample was analysed using reversed–phase C–18 column highperformance chromatography. The mobile phase consisted of 75% triethyl ammonium acetate buffer, 20% methanol and 5% acetonitrile. The analytes were monitored at 289 run and tetroxoprim was used as an internal standard. The maximum values for intra–day coefficients of variation (CV) for TMP and SMZ were 57 and 2, 1%, respectively. Interday CV values were 64 and 22%, respectively. The method was used to compare the bioavailability of two tablet formulations in terms of their pharmacokinetic parameters following oral administration of the tablets to 18 volunteers.

Deposition in a changing paleogulf: evidence from the Pliocene–Quaternary sedimentary succession of the Nile Delta, Egypt

Sedimentary complexes of ancient gulfs provide valuable information about paleoenvironmental dynamics. The study of several Pliocene–Pleistocene sections allowed reconstruction of the regional stratigraphical framework in the southwestern fringes of the Nile Delta. The Kafr El-Shiekh, the Gar El-Muluk, and the Kom El-Shelul formations of the Zanclean Age and the Wastani Formation of the Piacenzian Age constitute the Pliocene sedimentary succession in the study area. The establishment of 11 facies types related to 5 facies associations coupled with the results of the stratigraphical study indicate the existence of a paleogulf corresponding to the modern delta and lower valley of the Nile. This Nile Paleogulf appeared and reached its maximum spatial extent in the beginning of the Pliocene. Then, it retreated gradually and disappeared before the end of this epoch when alluvial sedimentation reestablished. There was significant flux of siliciclastic material to the study area. The Zanclean Flood in the Mediterranean Sea allowed marine incursion in the study area where the river valley incised during the precedent Messinian Salinity Crisis. Regional tectonic uplift and filling of the accommodation space with siliciclastic material from the eroded land were the main controls on the paleogulf evolution. Strengthened glaciation triggered global sea level fall, and alluvial deposition dominated the study area in the late Pliocene–Pleistocene.