A snapshot into the Oligocene vegetation of the Tethyan southern shores: new fossil pollen evidence from North Africa (Egypt)

Abstract

A palynological investigation was carried out on 24 samples from the Oligocene Dabaa Formation, which cuts across the Amana-1X well, located in the Abu El Gharadig Basin, north Western Desert, Egypt. Palynological evidence presented here suggests an early Oligocene age for the studied Dabaa Formation. In addition, the palynological assemblages provide supplementary evidence for depositional environments. They are generally indicative of outer-shelf to upper slope environment under oxic to anoxic conditions for the lower part of the studied Dabaa Formation, but infrequent occurrences of more diverse assemblages suggest an inner neritic marine environment for strata at some levels in the upper part of the studied section. It was during the Oligocene that marked floral changes leading to the development of modern plant associations began such as temperate deciduous forests (with e.g., Acer and Betulaceae) which expanded greatly in the mid latitudes. A distinctive vegetational pattern could be outlined within the deposition of the Dabaa Formation. This pattern includes mangroves represented by taxa such as Zonocostites ramonae, Psilatricolporites crassus and Verrucatosporites usmensis. Another considerably different association with plenty of the freshwater algae Botryococcus and Pediastrum spp. at this level or tropical forests at slightly elevated altitudes (ever wet climate) are dominated by a variety of tropical forest taxa including Malvaceae and Striatricolpites, together with Retitricolporites irregularis, Psilatricolporites operculatus, Retibrevitricolporites ibadanensis, Retitricolporites spp. and Psilamonocolpites spp. in addition to ferns and tree ferns where tropical floras dominate. Also recognized are elements of savanna or open woodland (less humid climate) taxa like Poaceae pollen (grass) such as Monoporopollenites annulatus associated with Amaranthaceae (e.g., Chenopodipollis multiplex), Cyperaceae spp., Echiperiporites estelae, Proteacidites cooksonii, Cicatricosisporites dorogensis and Pteris. Finally, the montane ecosystems may have occurred at the slopes of mountains including rare pollen assigned to Sapotaceae (Psilastephanocolporites spp.) and Anacardiaceae (Retitricolpites simplex) which are probably part of the palynoflora due to long-distance transport.

Keywords:

• Africa
• Egypt
• palaeoclimate
• vegetation
• palaeoenvironment
• palynology
• Dabaa Formation
• Oligocene

Acknowledgements

The authors are indebted to the Egyptian General Petroleum Corporation (EGPC) for providing the samples and well log for this study. H.E. acknowledges the financial support by the Alexander von Humboldt Foundation, Germany (EGY-1190326-GF-P). S.Y.E. is indebted to the Arab Fund Fellowships Programme, Kuwait, for financial support through a Distinguished Scholar Award that allowed a one-year research stay hosted by Martin Head (Brock University, Canada), their support and generosity are highly appreciated. The authors wish to thank both reviewers, Manuel Casas-Gallego and Frank H. Neumann, as well as the Editor, Matthew Pound, for their insightful comments and constructive criticism that helped to improve the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Haytham El Atfy

HAYTHAM EL ATFY is an associate professor at Mansoura University, from which he received a BSc in geology and an MSc in palynology. He received his PhD in geosciences (palynology and organic geochemistry) from Goethe University, Frankfurt, Germany, in 2014, and acquired experience in industrial palynology through work with GUPCO (BP), Egypt. He was recently a visiting scientist at the Senckenberg Research Institute, Germany. His research interests span all aspects of palynology and its applications in dating, palaeoenvironmental and palaeoclimatical reconstructions, and hydrocarbon exploration, particularly of the Mesozoic and Cenozoic and, to a lesser extent, the Palaeozoic. He has more recently become involved in organic geochemistry. Haytham is a member of the Palynological Society (AASP), the Micropalaeontological Society (TMS), Arbeitskreis für Paläaobotanik und Palynologie (APP), and the Paleontological Society of Egypt (PSE). Haytham is a recipient of many awards such as the Bernd Rendel Prize from the German Science Foundation (DFG), Egyptian Award of Excellence and Egyptian State Incentive Award.

Salah Y. El Beialy

SALAH Y. EL BEIALY is an emeritus professor of palynology at Mansoura University, and in 2011–2013 was Head of its Department of Geology. Salah has long been involved in stratigraphical palynology. He gained his BSc in 1975, an MSc in 1980 from Mansoura University and a PhD in 1985 from the University of Sheffield, UK, under the late Prof. Charles Downie, and acquired experience in industrial palynology through work with Paleoservices Ltd, Shell, BP and GUPCO, Egypt. In 2006, he spent a year as a Visiting International Scholar at Brock University, Canada, collaborating with Martin J.Head on a project funded by the Arab Fund for Social and Economic Development, Kuwait, under the ZAMLAT Fellowship Program. Salah’s main interests are in the application of palynology in dating, palaeoenvironmental interpretation, spore-colour maturity determination, and hydrocarbon exploration from the surface and subsurface Palaeozoic–Cenozoic of North Africa and the Middle East. Salah received the Mansoura University Prize for scientific excellence in 2009.

Mohamed K. Zobaa

MOHAMED K. ZOBAA is an assistant professor at the University of Texas Permian Basin. He leads the palynology and sedimentary organic matter research group focusing primarily on the accumulation, distribution, and diagenesis of organic matter in time and space and how they can be used to characterize petroleum systems through the interpretation of depositional paleoenvironments, kerogen type, and organic thermal maturity. He uses palynology and palynofacies analyses as primary proxies in his research but engages other disciplines and integrates a variety of tools to support and corroborate his research findings. These include, for example, programmed pyrolysis, XRD, XRF, vitrinite reflectance, and organic petrology. Dr. Zobaa has 20 years of research experience studying the stratigraphy, palynology, and sedimentary organic matter content of some of the world’s most important hydrocarbon-generating provinces (e.g., Gulf of Mexico, the Permian Basin in Texas, the San Juan Basin in New Mexico, the Williston Basin in North Dakota, and the North Western Desert of Egypt). His research results and methodologies have been published and documented in journals in the United States and internationally, such as the Geological Society of America Bulletin, Geosphere, Sedimentary Geology, Palaeogeography, Palaeoclimatology, Palaeoecology, and Marine and Petroleum Geology. Dr. Zobaa is the recipient of the prestigious University of Texas System’s Rising STARs Award ($500,000) to establish his Sedimentary Organic Matter and Hydrocarbon Source-Rock Research Laboratory, which is the first of its kind in the Permian Basin area, providing comprehensive research and development support to the local hydrocarbon exploration and production operators.

Asmaa A. Taha

ASMAA A. TAHA is an assistant lecturer in the Department of Geology, Faculty of Science, Mansoura University, Egypt since 2019. She got her BSc in Geology in 2011 and her MSc in 2019 from the above institution. Her main interests are in Paleogene Palynology and its applications in age dating, palaeoenvironmental interpretation, palaeoecology, palaeoclimatology and palynofacies and its uses in hydrocarbon exploration. She is a joint author on a number of publications dealing with the Paleogene Palynology and palynofacies of the north Western Desert, Egypt.

Dieter Uhl

DIETER UHL is currently the Head of the Section for Palaeoclimate and Palaeoenvironmental Research at the Senckenberg Research Institute and Natural History Museum in Frankfurt am Main (Germany) and also adjunct Professor at the University of Tübingen (Germany). He was awarded his Diploma in Biology in 1994 from Kaiserslautern University and his PhD (Dr. rer. nat.) in Palaeontology in 1999 from the University of Tübingen. Dieter is a member of International Organisation of Palaeobotany, Paläontologische Gesellschaft and a fellow of the Linnean Society of London. His main interest is on the use of fossil plants as palaeoenvironmental proxies. He has published about 200 scientific articles and chapters mostly in peer-reviewed journals and books.