Discovery of an outcropping Mass Transport Deposit (MTD) in the Palaeogene subalpine synclines of southeastern France: Implications on flexural sub-basin deformation - 27/05/14
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Abstract |
We document the sedimentary facies of a large Mass Transport Deposit (MTD) within the sand-rich sediment gravity flow-dominated deposits of the Eocene–Oligocene south-western Alpine forelands (Annot Sandstone system). The MTD with an approximated volume of several hundreds of cubic kilometres fills a sub-basin located in the Mont-Tournairet confined sub-basin. Autochthonous facies are very typical sediment gravity-flow deposits (thin-bedded classical turbidites and thick-bedded hyperconcentrated to concentrated flow deposits) that stratigraphically belong to the Annot Sandstone infill. Slumps and internal metre-large fold axes of the deformed stratigraphic intervals indicate a main transport direction towards the northwest. The seafloor instability that led to the mass-flow events within the Mont-Tournairet sub-basin could have been favoured by high sedimentation rates in a small, confined and tectonically active sub-basin, possibly enhanced by local structural deformation associated with the Triassic evaporites on the eastern side of the Mont-Tournairet confined basin. The presence of the MTD suggests that a period of increased flexural subsidence rate and basin deformation occurred in this portion of the subalpine foreland basin. Therefore, the MTD forms a stratigraphic marker of a period of tectonic activity.
Le texte complet de cet article est disponible en PDF.Keywords : Mass Transport Deposit, Mass flow facies, Confined turbidite systems, Annot Sandstone Formation
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Vol 346 - N° 1-2
P. 37-44 - janvier 2014 Retour au numéroBienvenue sur EM-consulte, la référence des professionnels de santé.
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