Sedimentologic and tectonic evolution of the Upper Cretaceous-Lower Tertiary succession at Wadi Qena, Egypt

Soliman, Mohamed A.; Habib, Mohamed E.; Ahmed, Ezzat A.

doi:10.1016/0037-0738(86)90009-6

Cited by 35 publications

(11 citation statements)

References 6 publications

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“…Germann et al (1985) and Soliman et al (1986) placed this boundary near the top of the shaley units (approximately at the upper transgressive surface in Fig. 2) and just below the appearance of well-developed ledge-forming bioclastic limestones and phosphorites (Fig.…”

Section: Eastern Desert Sequence: the 'Duwi Formation'mentioning

confidence: 93%

“…These deposits are interpreted as upward-coarsening prodelta muds and delta front sands and silts, respectively (Soliman et al 1986;Figs 2 and 12). Assuming simple linear subsidence in the basin, these upwards shoaling sediments mark the progradation (basinward shift) of a shallow water delta complex accompanying sea-level fall.…”

Section: Eastern Desert Sequence: the 'Duwi Formation'mentioning

confidence: 99%

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Depositional sequences of the Duwi, Sibâîya and Phosphate Formations, Egypt: phosphogenesis and glauconitization in a Late Cretaceous epeiric sea

Glenn

1990

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Sedimentary facies, depositional environments and stratigraphic relationships of the Upper Cretaceous Duwi, Sib~iya and Phosphate Formations in Egypt are summarized in order to shed light on the origins and interrelationships between phosphorites and their commonly associated facies. The distribution of phosphorites, glauconitic sands, organic carbon-rich shales, cherts and porcelanites, and bioclastic and fine-grained limestones are correlated in both space and time across the central phosphorite provenance of the country. The correlations are linked by means of sequence stratigraphic analysis and are tied to global eustatic sea-level curves.Two main depositional realms are inferred from the Campanian lithofacies assemblages: (1) a deeper-water hemipelagic environment accompanying maximum transgression dominated by deposition of phosphorites, organic carbon-rich shales and biosiliceous sediments, which, after maximum flooding, shoals upwards into (2) a progradational stage accompanying sea-level fail, during which oyster banks with brackish back-reef sediments (Eastern Desert) and deltaic sediments (upper Quseir Variegated Shale, Nile Valley) dominated eastern portions of the phosphorite belt, while greensands were reworked seaward from earlier inner shelf sediments in the west (Western Desert). These depositional realms encompass (1) transgressive to lower highstand systems tracts and (2) upper highstand to lowstand progradational wedge system tracts, respectively. The reoccurrence of lower Maastrichtian phosphatic shale, marl and associated phosphorite lithofacies at the top of the sequence indicates repetition of the sedimentary cycle.Both phosphorites and glauconitic greensands appear to be the result of current winnowing and reworking of authigenic grains from previously deposited sediments. The resulting deposits range in scale from thin lag layers, to amalgamated beds, to giant sand waves up to 10 m thick. In the Egyptian setting, the common factors linking massive phosphorite and glauconite occurrences may have been the co-occurrence of humid climate, deep lateritic weathering in hinterlands, anoxic bottom waters on the inner shelf, and high fluvial discharge rates of phosphorus and iron. Superimposed on these factors were influences of cross-shelf currents necessary to concentrate authigenic precipitates, and a sea level change, which acted to markedly reduce the diluting effects of siliciclastic detritus during rapid sea level rise, as well as vertically stack 'authigenic facies' during sea level fall.

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Section: Eastern Desert Sequence: the 'Duwi Formation'mentioning

confidence: 93%

Section: Eastern Desert Sequence: the 'Duwi Formation'mentioning

confidence: 99%

Depositional sequences of the Duwi, Sibâîya and Phosphate Formations, Egypt: phosphogenesis and glauconitization in a Late Cretaceous epeiric sea

Glenn

1990

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“…Mid to Late Cretaceous lagoonal dolomites and evaporates pass transgressively into latest Cretaceous chalks (Keeley, 1994). Across central Egypt, Early to Mid Campanian restricted marginal to shallow-marine shales are overlain by Late Campanian to early Maastrichtian thin but widespread shallow-marine sediments, which are phosphate rich (Glenn and Arthur, 1990;Soliman et al, 1986). These in turn are overlain by deeper-water marine marls and chalks of Maastrichtian age, in an overall transgressive succession.…”

Section: Transgressive Systems Tractmentioning

confidence: 99%

A Sequence Stratigraphic Synthesis of the North African Mesozoic

Carr

2003

Journal of Petroleum Geology

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A synthesis of the sedimentology and sequence stratigraphy of the Mesozoic succession of North Africa is presented. Two chronostratigraphic correlation panels have been constructed at roughly right angles to each other across North Africa, in approximately E‐W and NNW‐SSE orientations. The panels illustrate the way in which sedimentology and hydrocarbon geology vary across the continent through time. The Mesozoic succession is divided into two sequences (NA 6, Early Triassic to Middle Cretaceous; and NA 7, Middle to Late Cretaceous), for both of which sequence boundaries, maximum flooding surfaces and component systems tracts are defined. The systems tracts are of tens of Ma duration and approximate to the second‐order cycles of previous publications. New palaeogeographic reconstructions for North Africa for the Triassic, Jurassic and Cretaceous are illustrated, and a new sea level curve based on the panels and palaeogeographic reconstructions is compared to other published sea level curves.

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“…Said, 1962;Klitschet al, 1979;Ward&McDonald, 1979;Hendriks et al, 1984;Van Houten, Bhattacharyya & Mansour, 1984) and underlie deeper-water marine mark and chalks of the Maastrichtian Dakhla Formation (cf. Said, 1962;Mansour & Khallaf, 1979;Mansour, Youssef & El Younsi, 1979;Hendriks et al, 1984;Soliman, Habib & Ahmed, 1986). Collectively, the Upper Cretaceous sedimentary sequence was deposited in generally shallow epicontinental seas that extended across the northern margin of the Arabo-Nubian craton and deepened towards the Tethyan seaway to the north.…”

Section: S T R a T I G R A P H I C A L Framework A N D Geological S Ementioning

confidence: 99%

Anatomy and origin of a Cretaceous phosphorite‐greensand giant, Egypt

1990

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Late Cretaceous epicontinental phosphorites, porcelanites/cherts, dark‐coloured shales, glauconitic sandstones and bioclastic and fine‐grained carbonate rocks in Egypt are examined in terms of their overall depositional and diagenetic framework and stable isotopic and organic geochemical characteristics. Two main depositional realms are interpreted and correlated through sequence stratigraphic analysis: (1) a shallow hemipelagic environment accompanying initial stages of marine transgression and conducive to the formation of organic carbon‐rich shales, biosiliceous sediments and thick phosphorites, and (2) a relatively high energy depositional regime accompanying sea‐level fall during which deltas advanced, glauconites were reworked seaward and prograding oyster banks became periodically exposed to episodes of fresh water diagenesis, thereby promoting solution‐collapse phenomena in associated cherts. Lenticular to massive phosphorites are viewed as the result of current winnowing and concentration of authigenic grains initially precipitated in associated reducing shales and biosiliceous sediments. In eastern Egypt the phosphorites form winnowed lag layers, some of which may have been redeposited down slope in structural lows. In the west, these sands were concentrated into giant phosphorite sand waves built by reworking of penecontemporaneously deposited phosphatic muds during marine transgression. Carbon isotopic results substantiate interpretations from modern deposits for limitation of phosphate mineral precipitation with depth in sediments as a result of lattice poisoning. However, direct desorption of phosphorus to pore waters from detrital iron‐oxyhydroxide phases also may have been important in the Cretaceous setting, the iron reduced in this process being available for incorporation in glauconites. The main locus for authigenic glauconite precipitation appears to be where iron fluxes from regions of lateritic weathering were highest and near the boundary between oxygenated and reduced waters. This study suggests a model for the common coexistence of glauconites and phosphorites in the geological record. Although upwelling is often advocated as the origin of nearly all giant phosphorite deposits, we suggest that some of these may have been strongly influenced by fluvially derived phosphorus borne on particulates and desorbed from these compounds upon flocculation and/or reduction in bottom waters or pore waters.

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Sedimentologic and tectonic evolution of the Upper Cretaceous-Lower Tertiary succession at Wadi Qena, Egypt

Cited by 35 publications

References 6 publications

Depositional sequences of the Duwi, Sibâîya and Phosphate Formations, Egypt: phosphogenesis and glauconitization in a Late Cretaceous epeiric sea

Depositional sequences of the Duwi, Sibâîya and Phosphate Formations, Egypt: phosphogenesis and glauconitization in a Late Cretaceous epeiric sea

A Sequence Stratigraphic Synthesis of the North African Mesozoic

Anatomy and origin of a Cretaceous phosphorite‐greensand giant, Egypt

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