Upper Cretaceous–Palaeocene basin-margin alluvial fans documenting interaction between tectonic and environmental processes (Provence, SE France)
S. Leleu, J.-F. Ghienne, G. Manatschal, 2005. "Upper Cretaceous–Palaeocene basin-margin alluvial fans documenting interaction between tectonic and environmental processes (Provence, SE France)", Alluvial Fans: Geomorphology, Sedimentology, Dynamics, A. M. Harvey, A. E. Mather, M. Stokes
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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.
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Alluvial fans are important sedimentary environments. They trap sediment delivered from mountain source areas, and exert an important control on the delivery of sediment to downstream environments, to axial drainages and to sedimentary basins. They preserve a sensitive record of environmental change within the mountain source areas. Alluvial fan geomorphology and sedimentology reflect not only drainage basin size and geology, but change in response to tectonic, climatic and base-level controls. One of the challenges facing alluvial fan research is to resolve how these gross controls are reflected in alluvial fan dynamics and to apply the results of studies of modern fan processes and Quaternary fans to the understanding of sedimentary sequences in the rock record. This volume includes papers based on up-to-date research, and focuses on three themes: alluvial fan processes, dynamics of Quaternary alluvial fans and fan sedimentary sequences. Linking the papers is an emphasis on the controls of fan geomorphology, sedimentology and dynamics. This provides a basis for integration between geomorphological and sedimentological approaches, and an understanding how fluvial systems respond to tectonic, climatic and base-level changes.