Eocene planktonic foraminifera from the north Eastern Desert, Egypt: Biostratigraphic, paleoenvironmental and sequence stratigraphy implications

Abstract

The Eocene succession at Beni Suef -El Zaafarana District in north Eastern Desert is rich in planktonic foraminiferal assemblages. The main objectives of this work are to use the planktonic foraminifera to recognize the biostratigraphy for the Middle-Upper Eocene succession in the study area. Seventy planktonic foraminiferal species belonging to 20 genera and seven families are identified from the Eocene El Fashn and Beni Suef formations. Three planktonic foraminiferal biozones are recognized. These are from older to younger Morozovelloides crassatus Zone (late Middle Eocene) that is recorded from El Fashn Formation, Globigerinatheka semiinvoluta Zone (latest Middle Eocene -Late Eocene) and Globigerinatheka index Zone (Late Eocene age) that are recorded from the Beni Suef Formation while the Maadi Formation is found barren in planktonic foraminifera. These zones are correlated with those from nearby areas in Egypt and the Mediterranean regions. The Middle/Upper Eocene (Bartonian/Priabonian) boundary is discussed here in detail. The percentage of the planktonic foraminifera in the total foraminiferal content (P %) points to a change in water depth. There was a significant decrease in the planktonic/benthic foraminiferal ratio from the late Middle Eocene El Fashn Formation to the Late Eocene Maadi Formation at Beni Suef -El Zaafarana District. This ratio change supports a shallowing upward in paleodepth. Based on the lithology, planktonic/benthic ratio and the obtained water depth, the studied Eocene succession could be subdivided into four depositional sequences. These sequences agree with the global eustatic sea-level and the depositional sequences in nearby areas.

Assessment of Mineralogical and Geochemical Composition of Oligocene/Eocene Black Shale Deposits in Beni Suef Area, Egypt

“…e presence of planktonic foraminiferal species (Truncorotaloides rohri, Morozovella spp., Truncorotaloides spp., and Acarinina spp.) supports the Late-Middle Eocene (Bartonian) age of the El Fashn Formation [10,13,14].…”

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

“…The occurrence of index benthic foraminifers (Bulimina jacksonensis, Nummulites beaumonti), besides small-sized and spinose planktonic foraminiferal species (Acarinina spp., Morozovelloides spp. ), assign this rock unit to upper middle Eocene (Bartonian) [18,19,[21][22][23].…”

“…The exposure of Gebel Qarara (G. Qarara on Figure 1) lies at about 48 km southeast of Beni Suef, at latitude 28 • 37 37.2 N and longitude 30 • 55 29.1 E, whilst that at Gebel El Heiba (G. El Hadid) is located at approximately 34 km southeast Beni Suef City, at latitude 28 • 46 36.9 N and longitude 30 • 57 15.1 E (Figure 1). The detailed lithostratigraphic description and field investigation of the studied exposures allowed us to recognize two rock units from base to top, the Qarara and the El Fashn formations (Figure 2), which were named after reviewing the studies that have been carried out on the Eocene rocks of northern Egypt [15,18,19,[21][22][23][39][40][41][42][43][44][45][46][47][48]. These are briefly discussed and described from older to younger in the following chapter.…”

“…Therefore, geochemical analyses, together with micropaleontological investigations, perform an important role in reconstructing the paleoecologic conditions and constructing models for sea-level changes in response to changing inhabited areas, climate, and sedimentary supply [7][8][9][10][11]. 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].…”

“…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].…”