Jochen Kuss

The Middle Cretaceous carbonate ramp of the northern Sinai: sequence stratigraphy and facies distribution

Abstract The Middle Cretaceous carbonate ramp of the northern Sinai developed in two stages on a passive continental margin overlying basal rift suites. The lower delta-dominated ramp (Upper Aptian-Lower Albian) in the north evolved into the upper carbonate-dominated ramp (Middle Albian-Cenomanian) which covered the central and southeastern parts of the Sinai. The transition between the two ramp settings took place during a period of a second-order sea-level rise and a major change in climatic conditions. The sedimentary patterns are superimposed upon by higher-frequency relative sea-level changes. The influence of the third-order relative sea-level changes on the ramp deposition was reconstructed on the basis of facies patterns, sedimentary geometries, and the distribution of microfacies types. As regional tectonic movements were of subordinate importance, a sequence stratigraphic interpretation allows a fine-scale estimation of the changing ramp settings and their characteristics. The combined use of semiquantitative microfacies analysis and sequence stratigraphy allows study of the factors controlling deposition during the different systems tracts, including the respective microfacies distributions. These factors indicate that third-order sea-level fluctuations result not only in simple shifts of facies belts up and down the ramp but also in changing environmental factors such as water circulation, carbonate production and siliciclastic input.

Sedimentary response to basin inversion: Mid cretaceous-early tertiary pre- to syndeformational deposition at the Areif El Naqa anticline (Sinai, Egypt)

SummaryThe Areif El Naqa domal anticline in northeastern Sinai is part of the ‘Syrian Arc’ which represents an intraplate orogen that has been formed since the late Cretaceous by inversion of an older half-gaben system as a consequence of the collision of the African and Eurasian plates. The here studied pre- and syn-deformational Upper Albian to Lower Eocene sedimentary succession in the anticline was formed under shallow marine to hemipelagic conditions resulting in predominantly carbonate lithologies with only subordinate siliciclastic intercalations. The depositional history at Areif El Naqa has been reconstructed in terms of sequence stratigraphy on the basis of detailed sedimentological, biostratigraphical, and paleoecological investigations of ten sections including comparisons with age-equivalent successions further north and south as well as published data.Following a late Triassic-early Cretaceous extensional period, tectonically rather quiet conditions prevailed during deposition of the Albian-Turonian successions. Inversion started around the Coniacian. Three main phases of uplift have been determined for the Areif El Naqa anticline on the basis of evidence from lateral facies and thickness changes, local development of pronounced hiatuses, and in comparison to the sequence stratigraphic development in the tectonically quiet region of central east Sinai. The first major compressional phase is interpreted to have taken place in Coniacian-early Santonian times. It is characterized by pronounced facies and thickness changes which were documented in an earlier study byBartov et al. (1980). Nevertheless, inter-regional sea level changes still controlled deposition at Areif El Naqa during this period. The second pulse of tectonic uplift is indicated for the late Campanian-early Maastrichtian. This is based on siliciclastic deposits which are interpreted as having been reworked from older siliciclastic rocks uplifted in the anticlinal core. The third compressional pulse is inferred to be of middle Paleocene to early Eocene age as evidenced by a major hiatus in sections on the northern anticlinal flank. The uplift history at Areif El Naqa has been compared with the tectonic development in other parts of the Syrian Arc and in general seems to reflect major movements which occurred throughout the anticlines of the fold belt.

The sediments of Wadi Qena (Eastern Desert, Egypt)

Abstract The first deposition of near-shore sandstones on basement rock in the northern Wadi Qena area occurred during Lower Carboniferous times. Paleozoic deposits are overlain by similar sandstones of Cretaceous age with a large but inconspicuous hiatus between them representing erosion and non-deposition. A Cenomanian transgression inundated sandstones in the north as well as basement rock in the south. The Cenomanian and Turonian sea deposited marine and near-shore material in the Wadi Qena area, and only to the south of it were fluviatile beds laid down. The extant Red Sea Hills, at that time, represented a high and formed a peninsula extending in northerly direction into the shelf sea of the Tethys ocean. The sea withdrew in or after Coniacian times and the following erosion removed almost all Coniacian marine deposits. During Campanian times, the sea returned and also flooded the Red Sea Hill peninsula. Phosphoritic marls, at times of unrest, were redeposited as phosphorite sands in the south. Carbonate deposition followed, ending in Maastrichtian times. An erosional phase during the Cretaceous-Tertiary transition removed most of these chalks and limestones from the Wadi Qena area, and Paleocene and Eocene seas deposited limestone and mmarly chalk before a final regression marked the closure of the Tethys ocean.

Platform environments, microfacies and systems tracts of the upper Cenomanian-lower Santonian of Sinai, Egypt

SummaryFactors controlling grain composition and depositional environments of upper Cenomanian—Santonian limestones of Sinai are discussed. The mainly shallow-water, inner-platform setting investigated is subdivided into five major facies belts, each represented by several microfacies types (MFTs). Their lateral distribution patterns and their composition underline aclear relation between depositional environment and platform position. The facies belts include sandstones and quartzose packstones of siliciclastic shorefaces, mudstones and bioclastic wackestones of restricted lagoons, shallow-subtidal packstones with diverse benthic foraminifera and calcareous algae, bioclastic and/or oolitic grainstones of inner-platform shoals, and wackestones of deep open-marine environments.The microfacies distribution patterns of the Cenomanian-Santonian strata are evaluated with respect to local and regional large-scale environmental changes. While protected shallow-subtidal environments with only subordinate ooids and oncoids prevail during the late Cenomanian, high-energy oolithic shoals and carbonate sands occur locally during the middle and late Turonian. They were probably related to a change of the platform morphology and a reorganisation of the platform after a late Cenomanian drowning. In the Coniacian-Santonian, the lack of ooids, oncoids, and the decrease of calcareous algae versus an increase in siliciclastics indicate a shift to lower water temperature and to a more humid climate. Especially in the Turonian, the interplay between sea-level changes, accommodation, hydrodynamics, and siliciclastic input is reflected by lithofacies and biofacies interrelation-ships that are elaborated within individual systems tracts. In particular, increasing accommodation intensified circulation and wave-agitation and controlled the distribution of high-energy environments of the middle and upper Turonian trans-gressive systems tracts. During highstands protected innerplatform environments prevailed.

Maastrichtian-Early Eocene litho-biostratigraphy and palægeography of the northern Gulf of Suez region, Egypt

Abstract The Maastrichtian-Lower Eocene sediments on both sides of the northern Gulf of Suez can be subdivided into eight formal formations (including one group) and one informal formation that are described in detail. These lithostratigraphic units reflect three different environmental regimes of deposition or non-deposition. The first regime is characterised by uplift and erosion or non-deposition resulting mostly from the uplift of the Northern Galala/Wadi Araba structure, a branch of the Syrian Arc Foldbelt. The shallow water carbonate platform and slope deposits of the Late Campanian-Maastrichtian St Anthony Formation and the Paleocene-Lower Eocene Southern Galala and Garra Formations represent the second regime and are found north and south of the Northern Galala/Wadi Araba High. The third regime is represented by basinal chalks, marls and shales of the Maastrichtian Sudr Formation and of the Paleocene-Eocene Dakhla, Tarawan and Esna Formations, the Dakhla/Tarawan/Esna informal formation and the Thebes Group. The distribution and lateral interfingering of the above mentioned environmental regimes reflect different vertical movements, changing basin morphology, sea level changes and progradation of shallow water sediments and is illustrated on 11 palaeogeographic maps.

Orbital time scale, intra-platform basin correlation, carbon isotope stratigraphy and sea-level history of the Cenomanian–Turonian Eastern Levant platform, Jordan

Abstract Two Cenomanian–Turonian boundary (CTBE) sections (KB3 and GM3) of the Karak–Silla intra-platform basin of the Eastern Levant carbonate platform, Jordan, are correlated based on high-resolution calcimetry. KB3 contains black shales with over 7 wt% total organic carbon (TOC). GM3 was deposited at shallower water depth and reveals four conspicuous gypsum beds used for sea-level reconstruction. Spectral analysis of carbonate content and TOC reveals forcing, mainly by the 100 ka cycle of Earths orbit eccentricity. Whole rock stable carbon isotope data show a conspicuous positive δ13C excursion representing the Oceanic Anoxic Event 2 (OAE2). The carbon isotope records of KB3 and GM3 correspond well with the cycles in the δ13C record of the global stratotype (GSSP) at Pueblo (USA). The GSSP orbital timescale, thus, can be applied to the Jordan record. Furthermore, all stable isotope events defined in the English chalk reference record are recognized in Jordan. Our orbital model for the Jordan sequence-stratigraphical framework reveals approximately 1.2 (+0.2) Ma duration of a third-order sequence, proposed to represent one cycle of the long obliquity (1.2 Ma). This long-term period is superimposed on three fourth-order fluctuations of 400 ka length (long eccentricity; fourth-order sea-level fluctuations), each of which comprises four carbonate cycles (100 ka eccentricity; fifth-order sea-level fluctuations). Demise of the Levant platform occurred during the phase of decreasing δ13C values after OAE2 in the interval between the Cenomanian–Turonian (C–T) boundary and the end of the Early Turonian.

Timing of mid-Cretaceous carbonate platform depositional cycles, northern Sinai, Egypt

Abstract The northern Sinai Upper Aptian to Middle Cenomanian succession represents an example of a carbonate platform, where stratigraphic interpretations are mainly based on benthic foraminifera, ostracods and rudists. This paper presents a concept combining the stratigraphic study of benthic organisms with graphic correlation and sequence stratigraphy, at a scale that determines the timing of sequence boundaries and quantification of sediment-accumulation rates. Biostratigraphic analyses result in multibiostratigraphic zonations and contribute to a northern Sinai fossil range chart for benthic larger and smaller foraminifera, ostracods and rudists. The age interpretation results from the careful comparison of the ages given in the literature and the distribution patterns in the northern Sinai sections. The northern Sinai chart for many fossil ranges matches with other studies, but also indicates some exceptions. Ostracods were grouped into assemblages characterised by short local ranges, which enables the exact correlation of different sections. The use of graphic correlation techniques within this framework improves the stratigraphic resolution and results in timing of the sequence boundaries. These chronostratigraphic assignments allow comparison of the Sinai sequence boundaries with those described from other regions. Furthermore, graphic correlation measures long-term sediment-accumulation rates of the northern Sinai. Based on their variations, we calculate the relative sea-level changes, resulting in a detailed second-order sea-level curve. In the Upper Aptian to Middle Cenomanian succession, important changes in the long-term sediment-accumulation rate were measured. They reflect three second-order sea-level cycles, which subdivide a general relative sea-level rise. 18 sequences superimpose the second-order sea-level change: 3 sequences in the Upper Aptian, 11 sequences in the Albian, and 4 sequences in the Lower–Middle Cenomanian. Both sequence-stratigraphic patterns and long-term sea-level changes were compared with those from the Tethyan domain, the African/Arabian Plate and the western Pacific. Abundance and distribution of the Sinai sequence boundaries were similar to the patterns described from other regions. We distinguish between sequence boundaries with regional extent correlating with examples from the North African/Arabian Plate or the western Pacific, sequence boundaries of possibly global or Tethyan extent and the few sequence boundaries of local extent. The influence of the regional and global signals on the studied successions reflect the Sinai location between the southeastern and southwestern Tethyan realms. Local tectonics or changes in subsidence are only of subordinate importance for the creation of sequence boundaries. The comparison of the chronostratigraphic assignments of the second-order sea-level curve with other descriptions indicates a second-order relative sea-level history of its own for Sinai triggered by the interaction of subsidence, sediment supply and eustasy.

Shelf architectures of an isolated Late Cretaceous carbonate platform margin, Galala Mountains (Eastern Desert, Egypt)

Abstract An asymmetrical carbonate platform margin to basin transect has been investigated in the Upper Campanian–Maastrichtian succession of the Galala Mountains, northern Egypt. Identification of systems tracts and their lateral correlation was possible in slope sections only, whereas the monotonous chalk-marl alternations of the basinal sections could not be subdivided with respect to sequence stratigraphic terminology. The platform asymmetry is expressed by varying large-scale depositional architectures exhibiting a rimmed platform with a sigmoidal slope curvature in south-easterly dip-sections and a ramp with a linear slope curvature in south-westerly dip-sections. The rimmed platform is subdivided into a gentle upper slope and a steep lower slope. The platform formed as a result of the initial topography that was controlled by the tectonic uplift of the Northern Galala/Wadi Araba Syrian Arc structure. The calculated angles of the steep lower slope of the rimmed part range from 5 to 8°, whereas the ramp part has an angle of less than 0.1°.

Structural and basin evolution in Miocene time, southwestern Gulf of Suez, Egypt

Seismic-facies analysis and the subsurface tectonic evolution of the Western Sub-Basin (WSB)oftheGulfofSuez,Egypt,werestudiedbyseismicreflectiondataof45seismiclines.Eight of these lines were selected to illustrate the structural framework and depositional history of the WSB supported by the composition, velocity and vertical seismic profile (VSP) logs of ten wells. The analysis of two way time (TWT) structure-contour maps and rose diagrams revealed that the MiocenestrataaredissectedbyNE-SWtrendingfaultsoftheMorganAccommodationZone(MAZ). Northofthiszone,ageneraldiptowardsthenortheastisrecognized,southofthiszone,theregional dip is towards the southwest. The complex structural framework was the main factor controlling facieschangesofthesyn-depositionalMioceneunitsalongthestudyarea.

Middle Jurassic calcareous algae from the circum-Arabian area

SummaryCalcareous algae of the Middle Jurassic limestones from Northern Sinai have been investigated in detail with regard to facies and palecology. The aalenian? to Callovian sequence is more than 1000 m thick. It is composed of carbonates, sandstones, siltstones and claystones; all sediments are interpreted as platform margin and extended platform deposits. Oncoids—often composed of skeletal algae—are frequent constituents in many deposits of the protected shelf areas.This algal flora is compared with algae from Oxfordian limestones of a well in Lebanon and from Aalenian?—Callovian limestones of a well in South Ethiopia. The algal flora consists of 22 taxa of Chlorophyta, Cyanophyta, Rhodophyta and 3 taxa of algae incertae sedis.ZusammenfassungIm Zusammenhang mit faziellen und palökologischen Untersuchungen der mitteljurassischen Kalke des nördlichen Sinai wurde eine detaillierte Bearbeitung der Kalkalgen durchgeführt. Die mehr als 1000 m mächtige Abfolge (Aalenien?—Callovien) umfaßt Karbonate, Sand-, Siltund Tonsteine, die als Plattformrandablagerungen bzw. als Sedimente einer Karbonatplattform interpretiert werden. Onkoide—meist aus skelettragenden Algen zusammengesetzt—sind in den niedrigenergetischen Ablagerungen der geschützten Schelfbereiche häufig.Diese Algen wurden mit Algenfloren aus Oxford-Kalken einer Bohrung im Libanon, sowie einer Bohrung in Südäthiopien (Aalenien?-Callovien) und mit Beschreibungen jurassischer Kalkalgen von verschiedenen circum-Arabischen Vorkommen verglichen.Insgesamt wurden 22 Algentaxa beschrieben, die zu den Chlorophyta, Cyanophyta und Rhodophyta gehören; daneben konnten 3 Taxa von algae incertae sedis bestimmt werden.