Platform evolution around the Early Eocene Climatic Optimum (EECO) in a low latitude setting
Zusammenfassung der Projektergebnisse
Two Palaeogene carbonate platforms have been studied in the Eastern Mediterranean (Egypt) and Western Mediterranean (Spain) in order to reconstruct the evolution of the shelves during times of high climatic and tectonic variability. Reconstructions are based on field observations, high-resolution microfacies (e.g., larger benthic foraminifera, corals) and geochemical data (e.g., bulk carbon isotopes). The Paleocene to Early Eocene succession of the Galala Mountains in the Eastern Desert (Egypt) represents an excellent example for an isolated carbonate platform at the SE Tethyan shelf. Deposition at the platform is controlled by syn-depositional tectonism, climate and sea-level changes. Microfacies and geochemical analyses reveal repeated phases of tectonic uplift during the Early Eocene, which are linked to the massive deposition of siliciclastics and an increasing restriction of the Egyptian shelf. The termination of tectonic uplift is indicated by the shift to pure carbonate deposition and the recovery to open ocean conditions in the latest Early Eocene. Increased nutrient availability at the Galala platform throughout the Early Eocene is interpreted as a coupled effect of climaticallyinduced nutrient discharge from the African continent and tectonically-controlled eutrophication. Carbon isotope data document three significant negative carbon isotope excursions in the Galala succession. Those excursions are related to transient global hyperthermal events. The most prominent hyperthermal event, the Paleocene-Eocene Thermal Maximum (PETM), witnesses a prominent turnover of the larger benthic foraminifera species and a shift from coral-dominated assemblages to larger benthic foraminifera-dominated assemblages at the platform. During the Early Eocene corals are not recorded in the Galala succession, which has been attributed to the coupled impact of global warming and local nutrient excess. Further post-PETM hyperthermal events were documented in the Galala succession for the first time in a shallow-marine tropical environment. The negative carbon isotope excursions of Eocene Thermal Maximum 2 and 3 show a significantly smaller magnitude and do not demonstrate a biotic impact to shallow-benthic assemblages. In a second study, a compiled Paleocene – Early Oligocene succession of the Prebetic platform in SE Spain has been used to document the distribution of larger benthic foraminifera and corals during the Eocene global cooling interval. High resolution microfacies data reveal a recovery of the Prebetic coral fauna during the Late Eocene. The comparision with other Tethyan carbonate successions demonstrates that coral recovery is strongly dependend on latitude: Global cooling yielded to the recovery of coral communities in the northern Tethyan realm during the Bartonian. A prominent cooling event at the Bartonian-Priabonian boundary, associated with a demise of many symbiont-bearing larger foraminifera causes the proliferation of coral reefs in the northern Tethys and the recovery of corals in the southern Tethys. The massive temperature drop related to the Oi-1 glaciation at the Eocene-Oligocene boundary caused a transient decline in coral abundance, followed by the Tethyanwide proliferation of major coral built-ups. Local differences regarding the timing of coral recovery are amongst others related to syn-depositional tectonic activity or temporal nutrient excess.
Projektbezogene Publikationen (Auswahl)
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(2008) Decline of coral reefs during late Paleocene to early Eocene global warming. eEarth, 3: 19-26
Scheibner, C., Speijer, R.P.
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(2008) Late Paleocene–early Eocene Tethyan carbonate platform evolution - A response to long- and short-term paleoclimatic change. Earth-Sci Rev, 90: 71-102
Scheibner, C., Speijer, R.P.
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(2009) Multiple Early Eocene thermal maxima at low latitude platform carbonates – The Eocene succession of the Galala Mountains, Egypt. In: Crouch EM, Strong, CP, Hollis CJ, (eds.) (2009) Climatic and Biotic Events of the Paleogene (CBEP 2009), extended abstracts from an international conference in Wellington, New Zealand, 12-15 January 2009, GNS Science Miscellaneous Series 18: 70-74
Höntzsch S, Scheibner C, Marzouk AM, Rasser MW, Kuss HJ
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(2009) On the Origin of Nummulites: Urnummulites schaubi n.gen. n.sp. from the Late Paleocene of Egypt. Micropalaeontology 55: 413-420
Boukhary, M., Scheibner, C.
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(2009) Paleocene – Lower Eocene ostracods from the Southern Galala Plateau area (Eastern Desert, Egypt): impacts of tectonics and platform evolution on ostracode distribution. Revue de Micropaleontology 52: 149-192
Morsi, A.M.M., Scheibner, C.
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(2009) Recalibration of shallow-bentic zonations across the Paleocene- Eocene boundary: Evidences from Egypt, Geologica Acta, 7: 195-214
Scheibner, C., Speijer R.P.
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27th IAS Meeting of Sedimentology, Alghero, September 20-23, 2009: Early Eocene shallow-benthic communities – interactions between environment, climate and tectonics. In: Pascucci V & Andreucci S (eds.) Abstract book, p. 206, Sassari (Italy)
Höntzsch S, Scheibner C, Kuss HJ, Rasser MW, Marzouk AM
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Climatic and Biotic Events of the Paleogene (CBEP) Wellington, New Zealand 12-15 January 2009: Multiple Early Eocene thermal maxima at low latitude platform carbonates – The Eocene succession of the Galala Mountains, Egypt. In: Strong CP, Crouch EM, Hollis CJ, (eds.) Conference Program and Abstracts, GNS Miscellaneous Series 16, p. 108, Wellington, New Zealand
Höntzsch S, Scheibner C, Marzouk AM, Rasser MW, Kuss HJ
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Forams 2010, Bonn, September 5 – 10 2010: Larger benthic foraminifera in the Early Eocene hothouse and their impact to tectonic and climatic perturbations – a case study from Egypt. In: Langer M (2010), Abstracts with Program, p. 107, Bonn (Germany)
Höntzsch S, Scheibner C, Kuss HJ
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(2011) Increasing restriction of the Egyptian shelf during the Early Eocene? – New insights from a southern Tethyan carbonate platform. Palaegeography, Palaeoclimatology, Palaeoecology 302: 349-366
Höntzsch S., Scheibner C., Guasti, E., Kuss, H.J., Marzouk A., Rasser, M.W.
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(2011) Tectonically driven carbonate ramp evolution at the southern Tethyan shelf: the Lower Eocene succession of the Galala Mountains, Egypt. Facies 57: 51-72
Höntzsch S., Scheibner C., Kuss H.J., Marzouk A.M., Rasser M.W.
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New and Emerging Plays in the Eastern Mediterranean, Geological Society London, 23. – 25. 2. 2011: Multiple Pulses of Syrian Arc Uplift in the Early Palaeogene - New High Resolution Data from the Galala Mountains, Egypt. In: Belopolsky A, Craig J, Iliffe J, Tari G (2011), Abstracts with Program, pp. 26-27, London (UK)
Höntzsch S, Scheibner C, Kuss HJ
