Upper Cretaceous-Palaeocene basin-margin alluvial fans documenting interaction between tectonic and environmental processes (Provence, SE France)

Abstract

Abstract Upper Cretaceous-Palaeocene alluvial-fan conglomerates exposed along the northern margin of the Arc Basin (Provence, SE France) preserve a continuum between undeformed basinal deposits and syntectonic alluvial-fan deposits. Based on the distribution of facies associations and growth structures in the alluvial-fan deposits, and using marker levels and erosional surfaces, the tectono-sedimentary evolution of the basin margin is discussed. On a long timescale, the stratigraphic pattern in the alluvial-fan deposits mainly records the tectonic activity in the catchment, and subordinate out-of-syncline thrusts in the basin margin. On an intermediate timescale, evolution in the drainage area controls the spatial evolution of the alluvial fans and some minor changes in depositional facies. High-frequency cycles record aggradation-stabilization sequences, resulting in vertically superimposed alluvial-fan bodies more probably tectonically controlled, whereas alternation between conglomerates-siltstones at the scale of interbedding most probably reflects climatic cycles.