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Changements climatiques globaux et forçage tectonique au Paléogène. Exemples du Bassin de Paris et des Pyrénées

Abstract : Competition between tectonic and climate is expressed throughout the sedimentation. Because of the retroactions existing between those two parameters, it is often hard to discriminate their relative influence. The Cenozoic is a period characterised both by a global cooling and the establishment of many orogenesis. The aim of this work was to understand how retractions between climate, tectonics and sedimentation can be documented in an ancient mountain range - the Pyrenees. Three main questions were discussed : (1) does the growth of the Pyrenees can significantly impact the climate, locally or more globally? (2) how does climate and tectonics influence the sedimentation ? (3) may a climatic shift influence the tectonic evolution of the Pyrenees and how? The first part was treated using stable isotope geochemistry (δ18O and δ13C) on carbonate marine (molluscs and dasycladales) and continental (charophytes gyrogonites) biomineralisations from the Paris basin and the South-Pyrenean foreland basin. Results show that the global climatic events of the Paleogene were recorded by the fossils analysed in those two basins, with the early Eocene climatic optimum, the Lutetian cooling, the middle Eocene climatic optimum and the Eocene - Oligocene glaciation. It implies that the growth of the Pyrenees should not have a significant influence on the climate during the Paleogene. However, a shift between the δ18O values of oysters in the Paris basin and in the Pyrenees during the middle Eocene supposes that the Pyrenean topography was soon high and could be estimated near 2000 meters. The second was addressed from a field study about the Lutetian carbonate deposits. It has highlighted that the carbonate platforms disappeared definitively at the Lutetian - Bartonian limit. This evolution seems to result from an environmental stress in response to an increase of the erosional flux. This event is not correlated to a particular tectonic event but is however synchronous with a climatic instability and the establishment of a significant glacioeustatism. Finally, we try to highlight a relationship between the climate and the tectonic in the Pyrenees. We have established a kinematic model, to better evaluate the sequence of shortening in the western area of the South-Pyrenean basin. Three main periods of shortening are identified between the middle Eocene and the Miocene. The comparison between the frontal accretionary flux and the outcoming flux coming from the axial zone, deduced from bibliographic data, reveals that a strong increase in erosion happened around the Eocene - Oligocene boundary. This event corresponds to the main climatic rupture of the Cenozoic, suggesting a climatic forcing on the erosion and the elevation of the Pyrenees.
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https://tel.archives-ouvertes.fr/tel-00687530
Contributor : Damien Huyghe <>
Submitted on : Friday, April 13, 2012 - 2:10:10 PM
Last modification on : Friday, May 29, 2020 - 4:01:40 PM
Document(s) archivé(s) le : Saturday, July 14, 2012 - 2:25:45 AM

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  • HAL Id : tel-00687530, version 1

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Damien Huyghe. Changements climatiques globaux et forçage tectonique au Paléogène. Exemples du Bassin de Paris et des Pyrénées. Stratigraphie. Université Pierre et Marie Curie - Paris VI, 2010. Français. ⟨tel-00687530⟩

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