The Dababiya Quarry section: Lithostratigraphy, clay mineralogy, geochemistry and paleontology

The Global Standard Stratotype-section (GSSP) for the Paleocene/Eocene (P/E) boundary has been selected in the Dababiya Quarry, near Luxor, at the base of a lithostratigraphic unit where the base of the so-called Carbon Isotope Excursion (CIE) is recorded. The Dababiya Quarry offers remarkable three-dimensional exposures of the Upper Paleocene-Lower Eocene succession in the Nile Valley which comprises the Tarawan Chalk, the Esna Shale and the Thebes Limestone. The horizon that constitutes the P/E GSSP is located in the lower part of the Esna Shale Formation. This formation, remarkably thick (~130m) at Dababiya, is largely of homogenous gray shales. Its lower part includes, however, a thin lithostratigraphic unit in a typical succession of five characteristic beds that can be followed throughout Upper Egypt, and at the base of which the GSSP is defined. We formally describe this unit as the Dababiya Quarry Beds at the same time as we subdivide the Esna Shale Formation into three formal lithostratigraphic units. The Dababiya Quarry Beds constitute the lower part of Unit Esna 2. While we place emphasis on the description of the lithology, mineralogy, carbon isotope stratigraphy and paleontology of the Dababiya Beds, we provide a mineralogic and biostratigraphic framework for the whole exposure of Esna Shale at Dababiya that constitutes essentially a complete record from the base of calcareous nannofossil Zone NP9 to Zone NP11 and planktonic foraminiferal Zone P4 to P8. The carbon isotopic excursion, measured on organic matter is ~3m thick and has an amplitude of ~4‰. The planktonic foraminiferal excursion taxa are sporadic and the distinct Discoaster araneus-Rhomboaster spp. association is persistent throughout the CIE-interval

PETM effects in a shallow marine environment: benthic foraminiferal turnover and echinoid bloom (Sidi Nasseur, Tunisia).

Abstrac

Multiple Early Eocene carbon isotope excursions associated with environmental changes in the Dieppe-Hampshire Basin (NW Europe)

International audienceThe early Eocene experienced a series of short-lived global warming events, known as hyperthermals, associated with negative carbon isotope excursions (CIE). The Paleocene-Eocene Thermal Maximum (PETM or ETM-1) and Eocene Thermal Maximum 2 (ETM-2) are the two main events of this Epoch, both marked by massive sea-floor carbonate dissolution. Their timing, amplitude and impacts are rather well documented, but CIEs with lower amplitudes also associated with carbonate dissolution are still poorly studied (e.g. events E1 to H1), especially in the terrestrial realm where hiatus/disconformities and various sedimentary rates in a single succession may complicate the assignation to global isotopic events. Here we present a new high-resolution multi-proxy study on the terrestrial, lagoonal and shallow marine late Paleocene-early Eocene succession from two sites of the Cap d’Ailly area in the Dieppe- Hampshire Basin (Normandy, France). Carbon isotope data (δ13C) on bulk organic matter and higher- plant derived n-alkanes, and K-Ar ages on authigenic glauconite were determined to provide a stratigraphic framework. Palynofacies, distribution and hydrogen isotope values (δ2H) of higher-plant derived n-alkanes allowed us to unravel paleoenvironmental and paleoclimatic changes. In coastal sediments of the Cap d’Ailly area, δ13C values revealed two main negative CIEs, from base to top CIE1 and CIE2, and 3 less pronounced negative excursions older than the NP11 nannofossil biozone. While the CIE1 is clearly linked with the PETM initiation, the CIE2 could either correspond to 1) a second excursion within the PETM interval caused by strong local environmental changes or 2) a global carbon isotopic event that occurred between the PETM and ETM-2. Paleoenvironmental data indicated that both main CIEs were associated with dramatic changes such as eutrophication, algal and/or dinoflagellate blooms along with paleohydrological variations and an increase in seasonality. They revealed that the intervals immediately below these CIEs are also marked by environmental and climatic changes. Thus, this study shows either 1) a PETM marked by at least two distinct intervals of strong environmental and climatic changes or 2) at least one “minor” CIE: E1, E2, F or G, was associated with strong environmental and climatic changes similar to those that occurred during the PETM

L'excursion isotopique du carbone organique (delta 13 C org ) dans les paleoenvironnements continentaux de l'intervalle Paleocene/Eocene de Varangeville (Haute-Normandie)

International audienc

The PETM record revealed by a new integrated high-resolution dinoflagellate cyst and geochemical data from the "Sparnacian" sediments in the Paris and adjacent basins

International audienceThe Paris Basin represents an historical cradle of the Paleogene stratigraphy, where the Paleocene Epoch and the "Sparnacian Stage" have been erected (Schimper, 1874; Dollfus, 1880). As highlighted by Aubry et al. (2005), whereas the chronostratigraphic connotation of the Sparnacian Stage occurred to be controversial since its definition, modern studies of the Late Paleocene - Early Eocene interval have revealed that the so-called "Sparnacian" deposits encompass a remarkable and short (~170 kyr) episode in the Cenozoic history, the Paleocene-Eocene Thermal Maximum (PETM, ~55.8-55.6 Ma). However, due to a large development of diverse and laterally variable, predominantly lagoonal and non-marine facies, the Paris Basin Upper Paleocene-Lower Eocene succession is still poorly documented and needs an updated chronostratigraphic correlation with other Paleogene records in adjacent basins and worldwide. Since almost 45 years the dinoflagellate cyst stratigraphy has significantly contributed to correlations of the Thanetian-Ypresian deposits in the Paris and adjacent basins (Châteauneuf & Gruas-Cavagnetto, 1968, 1978; Gruas-Cavagnetto, 1974; Costa and Downie, 1976). Nevertheless, data published on dinoflagellate cysts distribution in the Paleogene sediments of those basins remain too scattered (see Aubry et al., 2005) and need to be calibrated to the most recent biozonations. With the aim at reconstructing the "Sparnacian" palaeoenvironments as well as ensuring correlation with the PETM (and its Carbon Isotopic Excursion, CIE) events and related processes, new or already well known "Sparnacian" Dieppe-Hampshire and Paris Basins key localities (Cap d'Ailly and Sotteville-sur-Mer sections, Therdonne and Sinceny cores) have been investigated in details palynologically and chemostratigraphically. According to our new high-resolution data, the CIE begins within the Mortemer Fm in terrestrial or coastal environments and continues until the top of the Soissonnais Fm (Quesnel et al, this meeting). Within the CIE, δ13Corg values fluctuate between -25 and -30 ‰, while above and below they fluctuate between -22 and -26 ‰. The CIE interval contained in the lagoonal and shallow marine units reveals an extremely pronounced (compared with other PETM records worldwide) Apectodinium-acme (70-98% of dinocyst assemblage), sometimes accompanied by Pediastrum-blooms (fresh water algae). As mentioned by Gruas-Cavagnetto (1974), dinoflagellate assemblages from the Dieppe-Hampshire and Paris Basins "Sparnacian" do not contain the key species Apectodinium augustum (nominate species of the A. augustum zone corresponding the PETM-interval worldwide, Crouch et al., 2001), whereas it is present in the northern Belgian Basin Tienen Fm (De Coninck, 1975, 1999) and is coeval there with the CIE and Apectodinium-acme interval (Steurbaut et al., 2000, 2003). However, our calibration of the Apectodinium-acme to the CIE in the Dieppe-Hampshire and Paris Basins suggests its attribution to the A. augustum zone. As it was previously noted from southern England (Powell et al., 1996), the absence of species A. augustum in the Anglo-Paris Basin may be explained by its restriction to more offshore conditions. In localities studied here dinocyst assemblages dominated by Apectodinium spp. are characterized by a significant number of longer (compared to the holotype) specimens of A. parvum, which could represent an ecological onshore substitute of species A. augustum during the PETM

New Integrated High-Resolution Dinoflagellate Cyst Stratigraphy and Litho- and Chemostratigraphy from the Paris and Dieppe–Hampshire Basins for the “Sparnacian”

The Paris Basin represents an historical cradle of Palaeogene stratigraphy, where during the nineteenth century the Palaeocene Series and the "Sparnacian Stage'' were established. As highlighted by Aubry et al. (2005), whereas the chronostratigraphic connotation of the "Sparnacian Stage'' has been controversial since its definition, modern studies of the late Palaeocene-early Eocene interval have revealed that the so-called "Sparnacian'' deposits encompass a remarkable and short (similar to 170 kyr) episode of the Cenozoic, the Palaeocene-Eocene Thermal Maximum (PETM, similar to 55.8-55.6 Ma). Dinoflagellate assemblages from the "Sparnacian'' of the Dieppe-Hampshire and Paris basins do not contain the key species Apectodinium augustum, whereas it is present in the northern Belgian Basin Tienen Formation and is coeval there with the CIE and the Apectodinium acme interval. However, our calibration of the Apectodinium acme to the CIE in the Dieppe-Hampshire and Paris basins suggests its attribution to the A. augustum zone. The absence of species A. augustum in the Anglo-Paris Basin may be explained by its restriction to more offshore conditions

African pollen database inventory of tree and shrub pollen types

African pollen data have been used in many empirical or quantitative palaeoenvironmental reconstructions. However, the pollen types used in these studies were not controlled and standardised, preventing the precise understanding of pollen-plant and pollen-climate relation that is necessary for the accurate quantification of continental scale climate change or ecological processes in the past. This paper presents a summary of the progress made with the African Pollen Database (APD) inventory of plant diversity from pollen data extracted from 276 fossil sites and more than 1500 modem samples, with a focus on tropical tree pollen types. This inventory (1145 taxa) gives, for each pollen taxon whose nomenclature is discussed, information on the habit, habitat and phytogeographical distribution of the plants they come from. Special attention has been paid to pollen types with similar morphology, which include several plant species or genera, whose biological or environmental parameters can differ considerably