THE MIDDLE/UPPER WÜRMIAN ALLUVIO-LOESSIC SEQUENCES OF QUINCIEUX AND LYON (RHÔNE-ALPES, FRANCE): FIRST PALAEOENVIRONMENTAL INTERPRETATIONS AND CORRELATIONS

International audience; In 2013 and 2015, two 8-m-thick loess sequences with palaeosols were excavated in the lower Saône River valley in two sites 20 km away. At Quincieux, the sequence developed on a low terrace of the Saône River shows a lower palaeosol complex with frost wedges, laminated silts including sparsed blocks from the Alps, a median palaeosol or brownish horizon, gray clayey loams with sandy beds, massive loess and a Holocene topsoil complex. At Lyon-Apollinaire, the sequence leaned on the southern relief surrounding the Vaise Plain shows a unique 6-m-thick palaeosol complex eroded at the top and overlaid by massive to laminated fine gray loamy sands cut off by modern constructions. Conversely to the little evidence of human presence in Quincieux, faunal remains have been found in all palaeosols. However, only the oldest palaeosol of Quincieux was partially excavated in 2014. Multi-indicator samplings have been performed to reconstruct the chronological, pedological and environmental contexts of human occupations. 14C ages obtained at the base of gray loams in both sites yield similar ages of 18 ka. OSL and 14C ages obtained in the median brownish horizon of Quincieux are coherent around 20 ka. Conversely, those of the lower palaeosol are more variable between 27 and 40 ka and remain to be discussed. Ages obtained at Lyon-Apollinaire are coherent and reveal that the base and the top of the palaeosol complex correlate with the lower palaeosol and median brownish horizon of Quincieux respectively. Local conditions – slope context away from the alluvial plain – could explain such a difference. The comparison of these two sequences, unique for the lower Saône River valley, with those of northern France is not straightforward.; En 2013 et 2015, deux séquences loessiques de 8 m d'épaisseur avec paléosols ont été mises au jour dans la basse vallée de la Saône sur deux sites distants de 20 km. La séquence de Quincieux, développée sur une basse terrasse de la Saône, montre un paléosol inférieur complexe à fentes de gel, des limons laminés avec des blocs d'origine alpine dispersés, un paléosol ou horizon brunifié médian, des limons argileux gris à lits sableux, des loess massifs et un dernier sol complexe, holocène. La séquence de LyonApollinaire, adossée au relief sud entourant la plaine de Vaise, montre un unique paléosol complexe (6 m) au sommet érodé, surmonté de sables fins, limoneux, gris, massifs à lités, tronqués par des aménagements contemporains. Les restes de faunes y sont peu nombreux à la différence de ceux, avec traces humaines, présents dans les paléosols de Quincieux mais dont seul le plus ancien a fait l'objet d'une fouille partielle en 2014. Des échantillonnages multiindicateurs ont été réalisés pour reconstituer les contextes chronologique, pédologique et environnemental des occupations humaines. Les dates 14 C obtenues à la base des sableslimoneux gris des deux séquences fournissent un âge similaire de 18 ka. Les différents âges obtenus (OSL et 14 C) dans l'horizon brunifié médian à Quincieux sont cohérents autour de 20 ka. En revanche, ceux du paléosol inférieur montre une variabilité plus importante entre 27 et 40 ka sujette à discussion. Pour LyonApollinaire, les datations obtenues, cohérentes, indiquent la complexité du paléosol dont la base et le sommet peuvent se corréler respectivement au paléosol inférieur et à l'horizon brunifié médian de Quincieux. Les condi tions stationnelles-contexte de versant éloigné de la plaine alluviale-pourraient expliquer cette différence. Ces séquences, uniques pour la basse vallée de la Saône, sont plus difficilement comparables avec celles du nord de la France. Mots-clés : loess, paléosols, faune, datations OSL, glaciation würmienne, Paléolithique moyen à supérieur, basse vallée de la Saône ABSTRACT THE MIDDLE/UPPER WÜRMIAN ALLUVIOLOESSIC SEQUENCES OF QUINCIEUX AND LYON (RHÔNEALPES, FRANCE): FIRST PALAEOENVIRONMENTAL INTERPRETATIONS AND CORRELATIONS In 2013 and 2015, two 8mthick loess sequences with palaeosols were excavated in the lower Saône River valley in two sites 20 km away. At Quincieux, the sequence developed on a low terrace of the Saône River shows a lower palaeosol complex with frost wedges, laminated silts including sparsed blocks from the Alps, a median palaeosol or brownish horizon, gray clayey loams with sandy beds, massive loess and a Holocene topsoil complex. At LyonApollinaire, the sequence leaned on the southern relief surrounding the Vaise Plain shows a unique 6mthick palaeosol complex eroded at the top and overlaid by massive to laminated fine gray loamy sands cut off by modern constructions. Conversely to the little evidence of human presence in Quincieux, faunal remains have been found in all palaeosols. However, only the oldest palaeosol of Quincieux was partially excavated in 2014. Multiindicator samplings have been performed to reconstruct the chronological, pedological and environmental contexts of human occupations. 14 C ages obtained at the base of gray loams in both sites yield similar ages of 18 ka. OSL and 14 C ages obtained in the median brownish horizon of Quincieux are coherent around 20 ka. Conversely, those of the lower palaeosol are more variable between 27 and 40 ka and remain to be discussed. Ages obtained at LyonApollinaire are coherent and reveal that the base and the top of the palaeosol complex correlate with the lower palaeosol and median brownish horizon of Quincieux respectively. Local conditions-slope context away from the alluvial plain-could explain such a difference. The comparison of these two sequences, unique for the lower Saône River valley, with those of northern France is not straightforward.