The Campanian-Eocene succession in Gabal Oweina area, Upper Egypt, covering six rock units (Quseir, Duwi, Dakhla, Tarawan, Esna and Thebes formations) was revised. The sedimentological and biostratigraphical detailed studies of the succession helped in reaching a high-resolution sequence stratigraphic classification that led to the recognition of five third-order depositional sequences and their associated surfaces and systems tracts. Also, the paleobathymetry deduced from the identified benthonic faunal assemblages, helped in giving some details about the characteristics and paleoenvironments of the identified sequences. The Campanian depositional sequence Dw/DkSQ1, includes both the Duwi and the lower part of the Dakhla formations, was laid down in a sea oscillating between inner to middle neritic depths, on shallow subtidal shelf, followed by a shallow inner neritic depths, on lagoonal environment. The Maastrichtian depositional sequence DkSQ2 encompass the middle part of the Dakhla Formation and was laid down in a relatively outer neritic to upper bathyal depths, on deep subtidal shelf, followed by inner neritic depths, on a shallow subtidal shelf at the end of the sequence marked by an intraformational conglomerate bed. The Danian depositional sequence DkSQ3 covers the upper part of the Dakhla Formation and started by a latest Maastrichtian- earliest Danian hiatus. It accumulated in gradually deepening waters reaching upper bathyal depths, on deep subtidal shelf, followed by middle neritic depths, on a shallow subtidal shelf. The Selandian-Thanetian depositional sequence Dk/T/EsSQ4 comprises the uppermost part of the Dakhla, Tarawan and the lower part of the Esna formations and began by Danian-Selandian hiatus. It accumulated in oscillating conditions between upper bathyal depths, on a deep subtidal shelf to middle neritic depths, on a shallow subtidal shelf. The Ypresian depositional sequence EsSQ5 consists of the main parts of the Esna Formation and initiated by Paleocene/Eocene hiatus. It was laid down in a gradually deepening sea reaching the deep upper bathyal depths on a deep subtidal shelf, before reaching shallow middle neritic depths on a shallow subtidal shelf. Four of the recognized five sequence boundaries (SB1, SB3, SB4 and SB5) coincide with global sea-level falls, while the other one (SB2) is related to a local tectonic in the studied area.

Detail field, litho- and bio-stratigraphic studies on the Upper Cretaceous-Lower Paleogene rocks exposed in the Eastern Desert of Egypt have provided an opportunity to evaluate the stratigraphy and the geological evolution of the sedimentary basin. Lithostratigraphically, seven rock units; Quseir, Duwi, Sudr, Dakhla, Tarawan, Esna and Thebes formations, are considered after amending and dropping various used rock units names. Rakhiyat Formation in the north is changed and amended into Quseir Formation which has been used and consolidated in all sectors. Duwi Formation in the south is time-equivalent to the lower part of Sudr Formation in the north. Sharawna Member at Gabal Oweina and Hamama Member at Gabal Qreiya in the south (previously related to Dakhla Formation) are changed and amended into Sudr Formation which extends laterally as a tongue toward the south due to the marine transgression during the Late Campanian-Early Maastrichtian age. Similarly, Owaina Member at Gabal Oweina and Beida Member at Gabal Qreiya in the south are changed and amended into Dakhla Formation. Upward Tarawan, Esna and Thebes formations are resting on the Dakhla Formation all over the study area. Biostratigraphically, the studied successions are subdivided into 23 planktonic foraminiferal zones covering the interval from Campanian to Ypresian age. Sedimentation processes of the studied sections are interrupted by several synsedimentary tectonic episodes related to the collision between African/Arabian and Eurasia plates during the closure of Tethys Ocean. The relative sealevel in the study area and global eustatic one together with the synsedimentary tectonic episodes is associated together.

Detail field, litho- and bio-stratigraphic studies on the Upper Cretaceous-Lower Paleogene rocks exposed in the Eastern Desert of Egypt have provided an opportunity to evaluate the stratigraphy and the geological evolution of the sedimentary basin. Lithostratigraphically, seven rock units; Quseir, Duwi, Sudr, Dakhla, Tarawan, Esna and Thebes formations, are considered after amending and dropping various used rock units names. Rakhiyat Formation in the north is changed and amended into Quseir Formation which has been used and consolidated in all sectors. Duwi Formation in the south is time-equivalent to the lower part of Sudr Formation in the north. Sharawna Member at Gabal Oweina and Hamama Member at Gabal Qreiya in the south (previously related to Dakhla Formation) are changed and amended into Sudr Formation which extends laterally as a tongue toward the south due to the marine transgression during the Late Campanian-Early Maastrichtian age. Similarly, Owaina Member at Gabal Oweina and Beida Member at Gabal Qreiya in the south are changed and amended into Dakhla Formation. Upward Tarawan, Esna and Thebes formations are resting on the Dakhla Formation all over the study area. Biostratigraphically, the studied successions are subdivided into 23 planktonic foraminiferal zones covering the interval from Campanian to Ypresian age. Sedimentation processes of the studied sections are interrupted by several synsedimentary tectonic episodes related to the collision between African/Arabian and Eurasia plates during the closure of Tethys Ocean. The relative sealevel in the study area and global eustatic one together with the synsedimentary tectonic episodes is associated together.

Detail field, litho- and bio-stratigraphic studies on the Upper Cretaceous-Lower Paleogene rocks exposed in the Eastern Desert of Egypt have provided an opportunity to evaluate the stratigraphy and the geological evolution of the sedimentary basin. Lithostratigraphically, seven rock units; Quseir, Duwi, Sudr, Dakhla, Tarawan, Esna and Thebes formations, are considered after amending and dropping various used rock units names. Rakhiyat Formation in the north is changed and amended into Quseir Formation which has been used and consolidated in all sectors. Duwi Formation in the south is time-equivalent to the lower part of Sudr Formation in the north. Sharawna Member at Gabal Oweina and Hamama Member at Gabal Qreiya in the south (previously related to Dakhla Formation) are changed and amended into Sudr Formation which extends laterally as a tongue toward the south due to the marine transgression during the Late Campanian-Early Maastrichtian age. Similarly, Owaina Member at Gabal Oweina and Beida Member at Gabal Qreiya in the south are changed and amended into Dakhla Formation. Upward Tarawan, Esna and Thebes formations are resting on the Dakhla Formation all over the study area. Biostratigraphically, the studied successions are subdivided into 23 planktonic foraminiferal zones covering the interval from Campanian to Ypresian age. Sedimentation processes of the studied sections are interrupted by several synsedimentary tectonic episodes related to the collision between African/Arabian and Eurasia plates during the closure of Tethys Ocean. The relative sealevel in the study area and global eustatic one together with the synsedimentary tectonic episodes is associated together.

Detail field, litho- and bio-stratigraphic studies on the Upper Cretaceous-Lower Paleogene rocks exposed in the Eastern Desert of Egypt have provided an opportunity to evaluate the stratigraphy and the geological evolution of the sedimentary basin. Lithostratigraphically, seven rock units; Quseir, Duwi, Sudr, Dakhla, Tarawan, Esna and Thebes formations, are considered after amending and dropping various used rock units names. Rakhiyat Formation in the north is changed and amended into Quseir Formation which has been used and consolidated in all sectors. Duwi Formation in the south is time-equivalent to the lower part of Sudr Formation in the north. Sharawna Member at Gabal Oweina and Hamama Member at Gabal Qreiya in the south (previously related to Dakhla Formation) are changed and amended into Sudr Formation which extends laterally as a tongue toward the south due to the marine transgression during the Late Campanian-Early Maastrichtian age. Similarly, Owaina Member at Gabal Oweina and Beida Member at Gabal Qreiya in the south are changed and amended into Dakhla Formation. Upward Tarawan, Esna and Thebes formations are resting on the Dakhla Formation all over the study area. Biostratigraphically, the studied successions are subdivided into 23 planktonic foraminiferal zones covering the interval from Campanian to Ypresian age. Sedimentation processes of the studied sections are interrupted by several synsedimentary tectonic episodes related to the collision between African/Arabian and Eurasia plates during the closure of Tethys Ocean. The relative sealevel in the study area and global eustatic one together with the synsedimentary tectonic episodes is associated together.

The present study depends on qualitative and quantitative analyses for the Late Paleocene-Early Eocene benthonic foraminifera at Darb Gaga area, Baris Oasis, Western Desert, Egypt. The study Late Paleocene-Early Eocene succession consists of two rock units; Esna Formation at base and Thebes Formation (lowermost part) at top. Esna Formation is subdivided into four members stratigraphically arranged as follow: El Hanadi, Dababiya Quarry, Darb Gaga and Abu Had. Dababiya Quarry Member (marker of the P/E boundary) is characterized by the occurrence of glauconitic grains at the base confirming a minor hiatus at the P/E boundary. This hiatus led to the missing of the beds no. 1 & 2 of the five beds (lowermost part) of Dababiya Quarry Member. Four benthonic foraminiferal events are defined during the Late Paleocene-Early Eocene interval. The first one is global event at the Paleocene/Eocene (P/E) boundary, and the remainder events are local and define during the Ypresian (Early Eocene). The first event is characterized by a rapid extinction and abrupt faunal changes for the benthonic foraminiferal assemblages. This event led to the extinction of about 80% of the Paleocene foraminiferal taxa. About 72% of these taxa are temporarily extinct and reappeared soon. This event is characterized by carbonate dissolution which suggesting oxygen deficiency of oceanic bottom waters and food supply changes. Afterwards, a recovery phase of the benthonic foraminifers is directly recorded above this event and probably due to improved depositional environmental conditions. Quantitative analyses of benthonic foraminiferal assemblages at Darb Gaga section, suggest an outer shelf paleoenvironmental setting during the deposition of El Hanadi, Dababiya Quarry and Darb Gaga sediments that changes to inner-middle shelf during the deposition of Abu Had Member and inner shelf of Thebes Formation. This succession is subdivided into four depositional sequences which are bracketed by unconformities and their correlative conformities depending on integrated field investigations, lithofacies and biofacies data. These sequences are controlled by sea-level changes and/or tectonic activities that prevailed during the deposition.

The present study depends on qualitative and quantitative analyses for the Late Paleocene-Early Eocene benthonic foraminifera at Darb Gaga area, Baris Oasis, Western Desert, Egypt. The study Late Paleocene-Early Eocene succession consists of two rock units; Esna Formation at base and Thebes Formation (lowermost part) at top. Esna Formation is subdivided into four members stratigraphically arranged as follow: El Hanadi, Dababiya Quarry, Darb Gaga and Abu Had. Dababiya Quarry Member (marker of the P/E boundary) is characterized by the occurrence of glauconitic grains at the base confirming a minor hiatus at the P/E boundary. This hiatus led to the missing of the beds no. 1 & 2 of the five beds (lowermost part) of Dababiya Quarry Member. Four benthonic foraminiferal events are defined during the Late Paleocene-Early Eocene interval. The first one is global event at the Paleocene/Eocene (P/E) boundary, and the remainder events are local and define during the Ypresian (Early Eocene). The first event is characterized by a rapid extinction and abrupt faunal changes for the benthonic foraminiferal assemblages. This event led to the extinction of about 80% of the Paleocene foraminiferal taxa. About 72% of these taxa are temporarily extinct and reappeared soon. This event is characterized by carbonate dissolution which suggesting oxygen deficiency of oceanic bottom waters and food supply changes. Afterwards, a recovery phase of the benthonic foraminifers is directly recorded above this event and probably due to improved depositional environmental conditions. Quantitative analyses of benthonic foraminiferal assemblages at Darb Gaga section, suggest an outer shelf paleoenvironmental setting during the deposition of El Hanadi, Dababiya Quarry and Darb Gaga sediments that changes to inner-middle shelf during the deposition of Abu Had Member and inner shelf of Thebes Formation. This succession is subdivided into four depositional sequences which are bracketed by unconformities and their correlative conformities depending on integrated field investigations, lithofacies and biofacies data. These sequences are controlled by sea-level changes and/or tectonic activities that prevailed during the deposition.

The current work used the conventional peridinioid-gonyaulacoid ratio (P/G) to devise a new concept of dinoflagellate cyst zonation called the dinoflagellate ecological zone (DEZ), which is based here on the peridinioid ecological zone (PEZ) and gonyaulacoid ecological zone (GEZ). The PEZ and GEZ were used successfully to further divide the thick monotonous carbonate succession (mid-Cenomanian to Campanian) in Q-72-1X well in the Eastern Desert of Egypt into smaller ecozones. PEZ and GEZ are practical and easy to use in subdividing large conventional biozones of the carbonate reservoirs into distinguishable, smaller ecozones when a finer resolution is necessary on a reservoir scale for production demands. This tool is suggested to be used in the hydrocarbon exploration industry with minimum knowledge of the taxonomy of the dinoflagellate cysts. The proposed PEZ and GEZ are related to local ecological conditions within the basin/hydrocarbon field (i.e. can be traced out laterally in an intra-basinal scale). This tool can be applied to any carbonate reservoirs in any petroliferous basin worldwide. Moreover, the P/G ratio, the relative abundances of the dinoflagellate cyst assemblages and other palynological parameters were used successfully to reveal the palaeodepositional settings of the identified PEZ and GEZ. Alternating, transgressive and regressive phases were identified, although a dissimilar species composition is observed in each of these ecozones. Environments were interchanging between the regressive, marginal marine to proximal inner neritic and the transgressive, distal inner to middle shelf settings. Three peridiniacean dinoflagellate cyst peaks were recorded, the middle Cenomanian Subtilisphaera peak, the middle Coniacian Isabelidinium, Chatangiella, and Manumiella peak, and the middle Santonian Isabelidinium peak.

The current investigation provides further insight into the petroliferous characteristics of the Abu Roash "G" Member, which is regarded as an important rock unit for the Egyptian oil industry. Forty-seven samples covering the "G" Member were selected from the BED 14-1 and BED 2-4 wells in the Abu Gharadig Basin and from the Abu Tunis 1X well in the Matruh Basin, both of which are located in the north Western Desert. An independent dating of the "G" rocks of BED 2-4 by benthic foraminifera and ostracods, in addition to palynological dating, suggests a middle-late Cenomanian age and provides the biochronostratigraphic framework for sequence stratigraphic analysis. Analysis of the vertical distribution of particulate organic matter defines three palynofacies types (PF). PF-1 represents the basal "G", where shales of the BED wells and calcareous shale of Abu Tunis 1X were deposited during a relative sea level rise in an outer middle shelf environment that experienced a notable high primary productivity. Prevailing reducing (suboxic-anoxic) conditions supported preservation of very high amounts of amorphous organic matter (AOM) in PF-1. PF-2 is equated to shales of the middle "G" of BED 14-1 and BED 2-4 and to calcareous shales and limestone of the upper "G" in Abu Tunis 1X. PF-2 was deposited during a relative sea level fall in an inner middle shelf setting under better-developed suboxic-anoxic conditions. PF-3 corresponds to the upper "G" of BED 14-1 and BED 2-4 and represents the shallowest setting, where sandy and silty shales were deposited during a pronounced sea level fall in an inner shelf environment. The same suboxic-anoxic conditions were prevailing during deposition of PF-3. Three bioevents were recorded, which could be of palaeoecological and/or biostratigraphic significance. These are Senegalinium aenigmaticum-Dinopterygium cladoides peak, Dinopterygium cladoides-Dinopterygium alatum peak, and an acme of Classopollis brasiliensis. Sequence stratigraphy of a transect of the four studied sections was carried out to understand the response of the particulate organic matter distribution and depositional system to the sea level changes. Three third-order, depositional genetic sequences were recognized and correlated with the global sea level curve (KCe 2, KCe 3, and KCe 4). The early highstand systems tract (eHST) of the genetically related KCe 3 in all wells is characterized by relatively rich organic matter, where combined remarkably low water circulation and insignificant dilution of organic matter with coarse terrigenous material probably supported good preservation of organic matter. Spatial distribution of the "G" rocks shows lateral facies changes. This was inferred from sedimentation of an organic-poor (avg. 0.8 TOC wt %), coarse clastic (sandy shales) facies in the studied area, Abu Gharadig Basin. Sedimentation changes laterally into a northeast and northwest organic-rich, finer clastic (shale, calcareous shales, and argillaceous limestone) facies in the western Matruh Basin. The robust anoxic conditions and very low dilution of organic matter by terrigenous influx enhanced the organic richness (avg. 2.4 TOC wt %) of these rocks, which resulted in the formation of promising hydrocarbon source rocks. Thus, for a successful hydrocarbon exploration in the north Western Desert, the promising source section of the "G" Member would be associated with shales, calcareous shales, and argillaceous limestone lithologies. Its depositional environment is mainly confined to outer middle and inner middle shelf settings that have widespread suboxic-anoxic conditions and show eHST pattern. In contrast, the regressive intervals that are denoted by the lowstand systems tract (LST) and/or the late HST (lHST) typify the relatively coarse clastics of good quality reservoir rocks that are characterized by poor organic richness due to dilution with terrigenous influx.

A palynofacies analysis was carried out on thirty ditch-cuttings from the Upper Cretaceous sequences drilled by the Salam-60 well in the ShushanBasin, north-western Egypt. Quantitative vertical distributions of palynomorphs and particulate organic matter exhibit two palynofacies (PF) types.PF-1 suggests deposition of the clastic-carbonate section of upper Bahariya and the lowermost “G” Member of Abu Roash in a brackish, proximalinner shelf environment of prevailing reducing (suboxic-anoxic) conditions that witnessed occasional local oxic-dysoxic conditions. A slight shiftfrom a proximal to a distal inner shelf environment that witnessed notable fluctuations resulted in deposition of the mainly carbonate section of theuppermost “G” and “F” to “C” members, during a late Cenomanian-Turonian marine transgression, under the same suboxic-anoxic conditions. Thisrelative sea level rise was mostly connected to the global late Cenomanian marine transgression. PF-2 represents the rest of the carbonate section(“B” and “A” members) of Abu Roash and Khoman formations, which was deposited in middle shelf environments of prominent suboxic-anoxicconditions during a major regional marine transgression that was mostly connected to the global Turonian-Maastrichtian eustatic sea level rise.Nevertheless, minor fluctuations in the local Turonian sea level may have occurred. Regional comparison indicates Bahariya and the “G” Memberof Abu Roash formations have similar marginal to inner shelf depositional settings across most of the northern Western Desert. Except at westernMatruh Basin, where they have a deeper open marine, middle shelf setting. The “F” to “C” members have an outer inner shelf setting in the coastalbasins (Shushan and Matruh basins) and a deeper, inner middle shelf setting at the central basinal area (Abu Gharadig Basin). This interbasinaldifference in their depositional settings is mostly related to the late Cretaceous tectonic differentiation of Abu Gharadig Basin. The “B” and “A”members of Abu Roash and Khoman formations were deposited in central Abu Gharadig and at southern Matruh basins in deeper, outer shelf andupper to middle slope settings in comparison to their suggested inner middle and outer middle shelf settings in Shushan Basin. This was due tothe progressive late Cretaceous tectonic development of Abu Gharadig and Matruh basins. Local pteridophytes on wet lowlands and conifers onelevated hinterlands were growing near Salam-60 under a regional warm and relatively dry palaeoclimate.© 2017 Elsevier Masson SAS. All rights reserved.