Planktonic Foraminifera of the Middle and Upper Eocene Successions at the Northwestern and Northeastern Sides of the Nile Valley, Egypt: Stratigraphic and Paleoenvironmental Implications
This study deals with the biostratigraphic determination and paleoenvironmental reconstruction of the middle–upper Eocene sediments along the northwestern and northeastern banks of the Nile Valley, Egypt. The studied successions are classified into four rock units as follow: The Qarara (Lutetian–Bar...
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| author | Safaa Abu Bakr Ibrahim M. Abd El-Gaied Sayed M. Abd El-Aziz Mostafa M. Sayed Abdelaziz Mahmoud |
| author_facet | Safaa Abu Bakr Ibrahim M. Abd El-Gaied Sayed M. Abd El-Aziz Mostafa M. Sayed Abdelaziz Mahmoud |
| author_sort | Safaa Abu Bakr |
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| description | This study deals with the biostratigraphic determination and paleoenvironmental reconstruction of the middle–upper Eocene sediments along the northwestern and northeastern banks of the Nile Valley, Egypt. The studied successions are classified into four rock units as follow: The Qarara (Lutetian–Bartonian), the El Fashn (Bartonian), the Gehannam, and the Beni Suef (Bartonian–Priabonian) formations. A total of eighty planktonic foraminifera species belonging to twenty-two genera and eight families are identified, and their vertical distribution enabled us to recognize four planktonic biozones, namely the <i>Morozovelloides lehneri</i> Zone (late Lutetian–early Bartonian), <i>Orbulinoides beckmanni</i> Zone (early Bartonian), <i>Morozovelloides crassatus</i> Zone (late Bartonian), and <i>Globigerinatheka semiinvoluta</i> Zone (late Bartonian–early Priabonian). The faunal assemblages characterizing these zones showed a great similarity with those recorded in the lower latitudes (tropical and sub-tropical) regions and correlated with the planktonic zones in the northern and southern Tethyan provinces. The appearance of <i>Orbulinoides beckmanni</i> distinguishes the early Bartonian period, its lowest occurrence defines the upper boundary of the <i>Morozovelloides lehneri</i> Zone, and its highest occurrence marks the lower boundary of the <i>Morozovelloides crassatus</i> Zone. The disappearance of the spinose forms of morozovellids and the large acarininids, besides the highest occurrence of <i>Morozovelloides crassatus,</i> defines the lower boundary of the <i>Globigerinatheka semiinvoluta</i> Zone. The middle/upper Eocene boundary is traced based on the last and first appearance of the marker planktonic species and located herein within the <i>Globigerinatheka semiinvoluta</i> Zone. The paleontological data, including the planktonic to benthic foraminiferal ratio (P/B), statistical analyses of different foraminiferal groups, and ternary plot diagrams in conjunction with the sedimentological features, indicate changes in the depositional settings, fluctuating between the inner to middle and outer neritic environment and the uppermost bathyal environment at some levels. |
| format | Article |
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| spelling | doaj-art-55a4dcb7595a41d2b8ed1e7de64c3ee22025-08-20T02:44:42ZengMDPI AGDiversity1424-28182025-02-0117211610.3390/d17020116Planktonic Foraminifera of the Middle and Upper Eocene Successions at the Northwestern and Northeastern Sides of the Nile Valley, Egypt: Stratigraphic and Paleoenvironmental ImplicationsSafaa Abu Bakr0Ibrahim M. Abd El-Gaied1Sayed M. Abd El-Aziz2Mostafa M. Sayed3Abdelaziz Mahmoud4Department of Geology, Faculty of Science, Helwan University, Cairo 11795, EgyptFaculty of Earth Science, Beni-Suef University, Beni-Suef 62511, EgyptDepartment of Geology, Faculty of Science, Fayoum University, Fayoum 63511, EgyptGeology Department, Faculty of Science, Beni-Suef University, Beni-Suef 62511, EgyptDepartment of Geology, Faculty of Science, Helwan University, Cairo 11795, EgyptThis study deals with the biostratigraphic determination and paleoenvironmental reconstruction of the middle–upper Eocene sediments along the northwestern and northeastern banks of the Nile Valley, Egypt. The studied successions are classified into four rock units as follow: The Qarara (Lutetian–Bartonian), the El Fashn (Bartonian), the Gehannam, and the Beni Suef (Bartonian–Priabonian) formations. A total of eighty planktonic foraminifera species belonging to twenty-two genera and eight families are identified, and their vertical distribution enabled us to recognize four planktonic biozones, namely the <i>Morozovelloides lehneri</i> Zone (late Lutetian–early Bartonian), <i>Orbulinoides beckmanni</i> Zone (early Bartonian), <i>Morozovelloides crassatus</i> Zone (late Bartonian), and <i>Globigerinatheka semiinvoluta</i> Zone (late Bartonian–early Priabonian). The faunal assemblages characterizing these zones showed a great similarity with those recorded in the lower latitudes (tropical and sub-tropical) regions and correlated with the planktonic zones in the northern and southern Tethyan provinces. The appearance of <i>Orbulinoides beckmanni</i> distinguishes the early Bartonian period, its lowest occurrence defines the upper boundary of the <i>Morozovelloides lehneri</i> Zone, and its highest occurrence marks the lower boundary of the <i>Morozovelloides crassatus</i> Zone. The disappearance of the spinose forms of morozovellids and the large acarininids, besides the highest occurrence of <i>Morozovelloides crassatus,</i> defines the lower boundary of the <i>Globigerinatheka semiinvoluta</i> Zone. The middle/upper Eocene boundary is traced based on the last and first appearance of the marker planktonic species and located herein within the <i>Globigerinatheka semiinvoluta</i> Zone. The paleontological data, including the planktonic to benthic foraminiferal ratio (P/B), statistical analyses of different foraminiferal groups, and ternary plot diagrams in conjunction with the sedimentological features, indicate changes in the depositional settings, fluctuating between the inner to middle and outer neritic environment and the uppermost bathyal environment at some levels.https://www.mdpi.com/1424-2818/17/2/116planktonic foraminiferaupper EoceneNile Valleypaleontological datadepositional settings |
| spellingShingle | Safaa Abu Bakr Ibrahim M. Abd El-Gaied Sayed M. Abd El-Aziz Mostafa M. Sayed Abdelaziz Mahmoud Planktonic Foraminifera of the Middle and Upper Eocene Successions at the Northwestern and Northeastern Sides of the Nile Valley, Egypt: Stratigraphic and Paleoenvironmental Implications Diversity planktonic foraminifera upper Eocene Nile Valley paleontological data depositional settings |
| title | Planktonic Foraminifera of the Middle and Upper Eocene Successions at the Northwestern and Northeastern Sides of the Nile Valley, Egypt: Stratigraphic and Paleoenvironmental Implications |
| title_full | Planktonic Foraminifera of the Middle and Upper Eocene Successions at the Northwestern and Northeastern Sides of the Nile Valley, Egypt: Stratigraphic and Paleoenvironmental Implications |
| title_fullStr | Planktonic Foraminifera of the Middle and Upper Eocene Successions at the Northwestern and Northeastern Sides of the Nile Valley, Egypt: Stratigraphic and Paleoenvironmental Implications |
| title_full_unstemmed | Planktonic Foraminifera of the Middle and Upper Eocene Successions at the Northwestern and Northeastern Sides of the Nile Valley, Egypt: Stratigraphic and Paleoenvironmental Implications |
| title_short | Planktonic Foraminifera of the Middle and Upper Eocene Successions at the Northwestern and Northeastern Sides of the Nile Valley, Egypt: Stratigraphic and Paleoenvironmental Implications |
| title_sort | planktonic foraminifera of the middle and upper eocene successions at the northwestern and northeastern sides of the nile valley egypt stratigraphic and paleoenvironmental implications |
| topic | planktonic foraminifera upper Eocene Nile Valley paleontological data depositional settings |
| url | https://www.mdpi.com/1424-2818/17/2/116 |
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