QUATERNARY AEOLIAN DEPOSITS OF THE AQUITAIN BASIN (SW FRANCE) : CHRONOSTRATIGRAPHY AND SPATIAL DISTRIBUTION

• Main Author: Sitzia, Luca
• Other Authors: De la Préhistoire à l'Actuel : Culture, Environnement et Anthropologie (PACEA), Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux I, PASCAL BERTRAN([e-mail])
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2014
• Subjects: aeolian deposits; periglacial; palaeoenvironment; palaeopedology; geochemistry; geostatistics; GIS; geomorphology; Aquitaine Basin; Lande's Erg; Landes de Gascogne Desert; peopling dynamics in desert environments; dépôts éoliens; périglaciaire; paléoenvironnement; paléopédologie; géochimie; géostatistique; SIG; géomorphologie; Bassin d'Aquitaine; Erg Landais; désert des Landes de Gascogne; dynamiques de peuplement en milieu désertique; [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology; [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy; [SHS.ARCHEO]Humanities and Social Sciences/Archaeology and Prehistory; Ice; Ice Sheet; permafrost
• Online Access: https://tel.archives-ouvertes.fr/tel-01009617; https://tel.archives-ouvertes.fr/tel-01009617/document; https://tel.archives-ouvertes.fr/tel-01009617/file/TheseSitziaL.pdf

Quaternary aeolian deposits in the Aquitaine Basin (SW France) provide rare evidence of fossil periglacial aeolian systems located some distance from ice-sheet margins. Studying such systems sheds light on aeolian dynamics in a region which, during glacial periods, lay between the northern European zone with continuous permafrost and the permafrost-free semi-arid/arid belt of southern Europe. Understanding the evolution of Quaternary aeolian deposits in southwestern France also adds further detail to reconstructing landscapes exploited by the region's Upper Paleolithic groups. Here, a chronostratigraphic synthesis of Pleistocene and Holocene aeolian sand deposits in the Landes region is presented alongside a cartographic analysis of the Aquitaine Basin's main aeolian facies. The chronostratigraphic framework presented here is based on a detailed stratigraphic analysis (sedimentary facies, palaeopedology) of numerous unpublished profiles and 75 new radiometric dates (OSL, ESR, 14C). Sand dune morphology, as well as the spatial distribution and origin of the different facies, are addressed using a combination of (1) a cartographic study of dunes with the help of GIS; 2) a geostatistical analysis of dune thickness variability and granulometric gradients; 3) a geochemical study of loess deposits and their potential sources. The above updates and adds new elements to our understanding of the Landes Erg, which developed as early as the Early Pleistocene. Middle Pleistocene aeolian sandsheets were also documented, which fits well with the regional loess record. A detailed Upper Pleistocene chronostratigraphy was also established, whose earliest phase (56-50 ka) corresponds to wet aeolian sandsheets that accumulated in relatively wet conditions and were influenced by changes in the level of the water-table. This facies corresponds to the development of large fields of transverse, low-amplitude barkhanoids ridges (zibar). During this phase, the development of a peaty gley demonstrates a reduction in aeolian sand ...