11 Oct 2022
11 Oct 2022
Status: this preprint is open for discussion and under review for Climate of the Past (CP).

Fluvio-deltaic record of increased sediment transport during the Middle Eocene Climatic Optimum (MECO), Southern Pyrenees, Spain

Sabí Peris Cabré1,2, Luis Valero1, Jorge E. Spangenberg3, Andreu Vinyoles4, Jean Verité1,5, Thierry Adatte6, Maxime Tremblin1, Stephen Watkins1, Nikhil Sharma1, Miguel Garcés4, Cai Puigdefàbregas1, and Sébastien Castelltort2 Sabí Peris Cabré et al.
  • 1DĂ©partement des Sciences de la Terre, UniversitĂ© de Genève, Genève, 1205, Switzerland
  • 2Departament de Geologia, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, 08193, Spain
  • 3Institute of Earth Surface Dynamics (IDYST), University of Lausanne, GĂ©opolis, Lausanne, 1015, Switzerland
  • 4Departament de DinĂ mica de la Terra i l’OceĂ , Facultat de Ciències de la Terra, Barcelona, 08028, Spain
  • 5DĂ©partment des Geosciences, UniversitĂ© de Rennes, Rennes, UMR 6118, France
  • 6Institute of Earth Sciences (ISTE), University of Lausanne, GĂ©opolis, Lausanne, 1015, Switzerland

Abstract. The early Cenozoic marine sedimentary record is punctuated by several brief episodes (< 200 kyr) of abrupt global warming, called hyperthermals, that have disturbed ocean life and water physicochemistry. Moreover, recent studies of fluvial-deltaic systems, for instance at the Palaeocene-Eocene Thermal Maximum, revealed that these hyperthermals also impacted the hydrologic cycle, triggering an increase in erosion and sediment transport at the Earth’s surface. Contrary to the early Cenozoic hyperthermals, the Middle Eocene Climatic Optimum (MECO), lasting from 40.5 to 40.0 Ma, constitutes an event of gradual warming that left a highly variable carbon isotopic signature and for which little data exist about its impact on Earth surface systems. In the South-Pyrenean Foreland Basin (SPFB), an episode of prominent deltaic progradation (Belsué-Atarés and Escanilla formations) in the middle Bartonian has been usually associated with increased Pyrenean tectonic activity, but recent magnetostratigraphic data suggest a possible coincidence between the progradation and the MECO warming period. To test this hypothesis, we measured the stable isotope composition of carbonates and organic matter of 257 samples in two sections of SPFB fluvial-deltaic successions covering the different phases of the MECO and already dated with magnetostratigraphy. We find a negative shift in 𝛿 18Ocarb and an unclear signal in 𝛿13Ccarb around the transition from magnetic Chron C18r to Chron C17r (middle Bartonian). These results allow, by correlation with reference sections in the Atlantic and Tethys, to identify the MECO and document its coincident relationship with the Belsué-Atarès fluvial-deltaic progradation. Despite its long duration and a more gradual temperature rise, the MECO in the South Pyrenean Foreland Basin may have led, like lower Cenozoic hyperthermals, to an increase in erosion and sediment transport that is manifested in the sedimentary record. The new data support the hypothesis of a more important hydrological response to the MECO than previously thought in mid latitude environments, including those around the Tethys.

Sabí Peris Cabré et al.

Status: open (until 22 Dec 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Review', Eric Barefoot, 01 Dec 2022 reply
  • RC2: 'Comment on egusphere-2022-891', Anonymous Referee #2, 06 Dec 2022 reply

Sabí Peris Cabré et al.

Sabí Peris Cabré et al.


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Short summary
The Middle Eocene Climatic Optimum (MECO) is a global warming event that took place 40 Ma ago and lasted ca. 500 ky, inducing physical, chemical, and biotic changes on the Earth. In this work, we use stable isotopes to identify the MECO in Eocene deltaic deposits of S. Pyrenees. Our findings reveal enhanced deltaic progradation during the MECO, pointing at the important impact of global warming on fluvial sediment transport with implications for the consequences of current climate change.