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Rep,. ifl' eel j i'O ll l: Sedimentary lIasins of the World, 3 (Series Editor: K.J. Hstil • • Edited by R.C. Selley DeparTment (~r Geology /11I/Jeria! Co f/ e~e of Scien ce . Technology and Medicine Royal Sd1001 (~f Mines London, Un ited Kin gdom • Sedimentary Basins of Egypt: An Overview of Dynamic Stratigraphy AHMED S. EL HAWAT ELSEVIER Amsterdam - Lausanne - New York - Oxford - Shannon - Tokyo 1997 Sedimentary Basins of Egypt: An Overview of Dynamic Stratigraphy AHMED S. EL HAWAT Initially, the quesliol1s lIIay be el e/llCllwl)' as 'WI/a/'?' and 'Where?' but soon the 'How,?' and 'When?' oj'proce.\",\', hislOty and geomell)' rake cellfer stage, ... one oflhe 1110.\'( rewording qiles l ion.~ thar Call be a~'ked is 'So what?' ... or 'Le i li S .w!e \Vlia! if mealls' R.N. Ginsburg ( 1982) - Seeking Answers INTRO DUCTION in thi s paper to extend sy nthesis across into these areas when possible. Strati graphic subdivisions and lnfo rm ation and literatu re on the geology of nomenclature are often confusing and names are Egypt has been gathered and publi shed by Said therefore not the objecti ve in this paper. They are ( 1962, 197 1, 1990), summarized by EI-Shazly used here as a reference to other workers in Egypt. ( 1977) and an updated annotated geological bibl i Stratigraphic sequences are treated in stead in terms ography was published by EI-B az ( 1984). The latest of time, space, events, cycles and facies. volume on the Geology of Egypt edited by Said The first part of this paper deals with an overview ( 1990) is the most comprehensive reference on the of the Proterozoic evolu tion of the Afro-Nubi an cra subject to date. ton and the development of Phanerozoic sedimentary During the last few decades, exciting new re basins. The fo ll owing sections trace basinal develop search has been done by geoscienti sts fro m Egyptian ment through the Palaeozoic, Mesozoic and Tertiary and intern ati onal academic in stitutions, oil compa times. Each of these sections is concl uded with ni es. and government departments, such as the Ge a subsection hi ghl ighting the relatio nship between ological Survey of Egypt. These publicati ons have sedimentation and signi fica nt geologic events whi ch conrri buted a great deal towards our current under have taken place during thal particul ar time. The standing of the sedimentary basins of Egypt. In my last section is a su mmary and synthesis of common view, some of the most signi ficant contributions to themes of the geologic history of the deposi ti onal the geology of Egypt were based on the appli ca basins of Egypt. tion of the concepts of plate tectonics, global sea level changes, stratigraphy and sedimentology. The solution of the Nubian Sandstone problem in North SEDIMENTA RY BASINS Afri ca and the Middle East (Klitzsch et aI. , 1979; Kli tzsch, I 990a; Klitzsch and Squyres, 1990; Van The Afro-N ubian craton Houten, 1980; Van Houten et aI. , J 984, to menti on j ust a few) is a case of a poin t. The basement complex of Egypt is exposed north Because of th e vo lume and the detailed nature and west of the Red Sea and the Gul f of Suez, in of published material on the Egyptian geology, the the areas of Sinai and the Eastern Desert. It extends present work attempts to retrace basinal development south of latitude 24° north of Jabal Uweinat and in Egypt, and concisely present it in the li ght of Aswan. Basement exposures represelll about 10% dynami c regional and global events through time. of the total area of Egypt, the rest are covered by Since Libya and Tunisia were influenced by the Phanerozoic sediments whi ch increase progressively same events as Egypt a conscious attempt is made in thickness northwards fo ll owing the regional dip Aji·icGI/ Basins. Sedimel1lary Basins of the World, 3 edited by R.C. Selley (Series Editor: KJ . Hsti). pp. 39-85. © 1997 Elsevier Science B.V., Amsterdam. All rights reserved. 40 A.S. EL HAWAT of African plate towards the Mediterranean Sea. and granodiorite plutonic bodies. These were later Irregul ar thickness distribution of the Phanerozoic partly metamorphosed into gneisses (890-876 Ma). sedimentary cover and basin development were in (3) Post-orogenic geosynclinal volcanic phase (665- flu enced by basement structures and tectonic hi story 654 Ma). (4) Development of post orogenic foreland since the Precambrian. basin s and molass sedimentation. (5) Late orogenic The basement complex of Egypt was recently re and post orogenic plutonic intru sions of granites and viewed by EI Gaby et al. ( 1990), Ri chter and Schan granodiorites (656-480 Ma). It was noted that in th e delm eier (1990) and Hassan and Hashad (1990). high mountai n areas, th e Nubian craton are formed In their study of th e structural development of the of orogenic granites and develop a 30 to 40 km thick basement complex of the northeast African plate, crust. Whereas the crust at the margin of the Red Schandelmeier et al. ( 1987) have subdivided the Sea trough is 20 km thick and consists of alkaline basement into two di stinctive parts, the pre-Pan metasomati c granites belonging to the latest plutonic African eastern Saharan craton and the Pan-African intrusions (EI-Shazly, 1977). The cru stal thickness Nubi an shield (Fig. I). of the east Saharan craton al so, exhibits similar or The eastern Saharan craton is located west of der of magnitude from Jabal Uweinat area to the the ri ver Nil e. The oldest of these pre-Pan-African Mediterranean coast. rocks are exposed in labal Uwainat which is located The Proterozoic Pan-A frican crustal accretion and southwest of Egypt and southeastern Libya. These subsequent continent to continent collision was as are dominated by granulite meramorphic rocks dated sociated with major development of transcontinental as Late Archean (2673 Ma) in age (Klerx, 1980). shear zones caused by strike-slip moti on parallel These rocks may represent a protocrust which was to the west African continental nu cleus (Morgan , developed as a result of compressive tectonics dur 1990, fi g. 7.4). Reactivation of these shear zones and in g continent to continent collision (Morgan, 1990). lineaments had a Significant influence on the devel Outwards from the Archean nucleus the craton con opment and evolution of sedimentary basins during sists of younger rocks that range from Early to Mid the Phanerozoic. dl e Proterozoic in age (Richter and Schandelmeier, In contrast to the spectacular Proterozoic events, 1990). These polymetamorphic and granitoid rocks tectoni cs and sedim entation during the Phanero are 2300 to 1800m years old and are arranged in zoic were relatively placid. During the Phanerozoic, a regional NW- SW, N-S, and E-W trending meta events were consistent with the cratonal evolutionary morphi c belt extending throughout northeast Afri ca process. Events were often initiated by uplifting of (Schandelmeier et aI., 1987). These authors rec cratonic areas due to the therma l expansion resulting ognized three stages of deformation that include: from the development of hot spot anomalies beneath ( I) initial folding (2 100 Ma), (2) development of the craton. Sedimentary basins were developed fol transcontinental shear zones and sigmoidal bend lowing crustal attenuation and fracturi ng of uplifted ing of metamorphic foliation (2000 Ma), and (3) areas and subsequent faulting and subsidence. Basi the development of l ebel Uweinat-lebel Kamil, 55' nal fillin g often produce symmetrical or asymmet dextral wrench faults, and 150' trending structural rical depositional cycles which usually startS with lineaments ( 1800 Ma). basal clastics followed by shall ow marine c lastics During Late Proterozoic, a second deformational and carbonate and, in some cases, evaporites. These event known as the Pan-African thermo-tectonic depositional cycles reflect stages of basinal subsi event took place. It resulted in thermal expansion dence and subsequent marine transgression. This is a and uplift of the basement, and in accretion of the common theme of tectonics and sedimentation in the oceanic cru st assemblage of the Nubian shield to Egyptian basins. Based on their individual tectonic the eastern margin of the Saharan craton. Extensive and depositional hi story a variation on the theme sllldies were published 0 11 the Nubian shield expo may occur. Sedimentary basins of Egypt are either sure in Sinai and the Eastern Desert east of the Nile intracratonic basins, pericratonic or ri fts bas ins. (EI Gaby et aI. , 1990; Morgan 1990). Five main evolutionary development stages rep Intracratonic basins resenting a complex hi story of crustal subduction of arc - trench system leading to accretion onto the east The Dakhla and Upper Ni le basins are broad African continental nucleus are recognized (EI Sha intracratonic depocentres which were developed in zly, 1977). These stages are : (J) Eugeosynclinal fly southern and central Egypt durin g th e Palaeozoi c sch sedimentation associated with island arc volcan and Mesozoic (Fig. 2) . They have evolved as a result ism and crustal subduction ( I 195- 856 Ma). These of structural differentiation and subsidence of the sediments and associated ophiolites were regionally rigid cratonic plate. Morgan (1990) suggested that metamorphosed and folded by later orogenic events. subsidence in Dakhla and the adjacent Kufra basin (2) Orogenic and syn-orogenic intru sion of granite in Libya was initi ated in response to cooling and SEDIMENTARY BASINS OF EGYPT: AN OVERVIEW OF DYNAMIC STRATIGRAPHY 4 1 ° hi E 01 T ERR A N E.• A:.:N:.. ___ • - I , " SEA ( - .