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Stéphane Mustafa AL REDA

Sediment routing in the syn-orogenic series of the Aquitaine Basin

Supervisors :
Jocelyn Barbarand and Cécile Gautheron – GEOPS- Université Paris-Sud
Eric Lasseur and Justine Briais – BRGM
Nicolas Loget – ISTeP, Sorbonne Université

Major Results

The study of the syn-orogenic deposits in the Aquitaine Basin have demonstrated the deposition of ~ 1 km of sediments during the late Eocene – Oligocene time, followed by a Miocene erosion in the basin. These episodes are interpreted as at the origin of the development of high elevation-low relief surfaces in the Pyrenees. The evolution of the source area have also been characterized.

Abstract

This thesis is focused on the understanding of the infilling of the Corbières region during the Eocene. Multiple approaches have been combined together to reconstruct the sediment routing system during the Eocene. The characterization of the depositional environments has led to the reconstruction of the evolution of the gravel front from the early to middle Eocene. Low temperature thermochronology data obtained for granite clasts showed apatite fission track ages more recent from east to west and dispersed AHe ages. Inverse thermal history modelling indicates that the Corbières region experienced a post-deposition kilometric burial and a subsequent Miocene exhumation characterized by erosion of detrital sediments.

Zircon U/Pb geochronology applied for conglomerate matrix and granite clasts allowed the identification of the source areas of the deposited sediments. Most of the obtained ages are Variscan. Results are coupled to Raman spectroscopy analysis and paleocurrent measurements in order to determine the drainage area for each unit. The late Ypresian – Lutetian sediments are fed from the North Pyrenean Zone. The Bartonian sediments are sourced from the Axial Zone and the Priabonian sediments show multiple sources from the eastern and central Pyrenees. Obtained results allowed the reconstruction of the sediment routing system in the Corbières basin during the Eocene.

Reconstruction of the Western Aquitaine basin paleo-burial of the according to our new low-Temperature thermochronology results.

PhD Thesis: Traçage des sédiments dans les séries syn-orogéniques du Bassin d’Aquitaine.

Stephane Mustafa Al-Reda, Université Paris-Saclay, 2020.

keywords: Continental sedimentation, Basin architecture, Drainage reconstruction, Sediment sourcing, Chemo-stratigraphy

DOI: https://www.theses.fr/2020UPASS100