Relationships between sequence stratigraphy and diagenesis of corals and foraminifers in the Middle Eocene, northern Egypt

Abstract

Outcrops of the Middle Eocene in northern Egypt represent a Tethyan reef-rimmed carbonate platform with bedded innerplatform facies. The diagenesis of these outcrops was studied in detail. The facies are characterized by a reef core, back reef and outer lagoon, shoal, inner lagoon, and tidal flat carbonate sequences. The diagenetic sequences on the scleractinian corals and foraminifers were thoroughly examined. These sequences show various diagenetic features during episodes of fluctuating sea levels and appear to be related to the primary composition of the studied components and the transgressive-regressive cycles. The carbonate diagenetic history of the examined samples successively includes marine-phreatic, mixed marine-meteoric, and shallow burial diagenesis. Most of the coral samples are affected by micritization and neomorphism and most of the foraminiferal samples are affected by micritization, dolomitization, glauconitization, or cementation. A sequence-stratigraphic analysis was carried out by integrating field and laboratory studies. The investigated sections were subdivided into three third-order sequences named S1, S2, and S3. The distribution of diagenetic fabrics was compared to a sequence stratigraphic framework. This has resulted in, for example, recording isopachous cement and autochthonous glauconitization mostly in the transgressive parts, while dolomitization, drusy cement, and biomoldic and vuggy porosities are recorded in the regressive parts; dedolomitization, allochthonous glauconitization, and ferrugination processes occurred at the sequence boundaries.

Diversity and renewal of tropical elasmobranchs around the Middle Eocene Climatic Optimum (MECO) in North Africa: New data from the lagoonal deposits of Djebel el Kébar, Central Tunisia

“…is considered as overlying the Midawara Fm. of Fayum (see also Abu Elgarh, 2012; King et al, 2014;Tawfik et al, 2016;Helal and Holcoval, 2017) and thus, be dated in fact to the early/mid Bartonian. However, Strougo et al (2007) preliminary proposed a Lutetian age from available fossil assemblages at that time, arguing that the stratigraphical correlation of the glauconitic horizon with the Fayum formations remains unclear, and that the elasmobranch and bivalve assemblages show strong affinities with Lutetian faunas known from elsewhere (e.g., "Carcharias" koerti, Galeocerdo eaglesomei).…”

Paleoclimate and Paleoenvironment Reconstructions from Middle Eocene Successions at Beni-Suef, Egypt: Foraminiferal Assemblages and Geochemical Approaches

“…Many authors focused on studying the Eocene strata of Egypt concerning paleontology, lithostratigraphy, biostratigraphy, and paleoecology [12][13][14][15][16][17][18][19][20][21][22][23][24]. Along the broad North African shelf, the middle Eocene rocks of Egypt are exposed in different localities showing distinctive facies changes from carbonates to clastics, all marked by the occurrence of distinctive Southern Tethyan foraminiferal assemblages [18][19][20][21][22][23][25][26][27][28]. Here, benthic foraminifera are more abundant than planktonic foraminifera, so only they can be used for biostratigraphic purposes [19,20,[29][30][31][32][33][34].…”

Traces of Mediterranean origin Holocene transgression in the drainage basin of Riva-Çayağzı Creek of the Black Sea (northeastern İstanbul-Turkey)

“…According to the Late Quaternary stratigraphy of the Black Sea, during the last glacial melting period (about 13,000-160,000 years ago), fresh waters flooded into the Caspian Sea, Black Sea, and Sea of Marmara with the melting of some main rivers such as the Bug, Danube, Dniester, and Dnieper due to the melting of Scandinavian glaciers, and the complete region became a partly interconnected freshwater lake system before the Mediterranean transgression. The first Mollusca community is the representative community of this period and the stratigraphic correspondent of this period is called Neoeuxinian (Late Pleistocene) (Görür et al, 2001;Yanko-Hombach, 2007;Yanko-Hombach et al, 2007;Büyükmeriç, 2016;Tawfık et al, 2017;Büyükmeriç et al, 2018). Some rivers flowing into the Black Sea deposited sedimentary lithological materials in the areas where rivers meet the seas.…”