Coarse-Grained Low-Sinuosity River Deposits: Example from Plio-Pleistocene Valdarno Basin, Italy
Published:January 01, 1987
Paolo Billi, Maurizio Magi, Mario Sagri, 1987. "Coarse-Grained Low-Sinuosity River Deposits: Example from Plio-Pleistocene Valdarno Basin, Italy", Recent Developments in Fluvial Sedimentology, Frank G. Ethridge, Romeo M. Flores, Michael D. Harvey
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The coarse-grained fluvial deposits of the Plio-Pleistocene Valdarno intermontane basin consist of massive or cross-stratified coarse gravel grading upward into cross-laminated sand overlain by massive overbank silt and clay with widespread pseudogley pedogenesis. The overall characteristics of such deposits (fining upward, abundance of overbank sediments, occurrence of extensive planar cross-stratification) would suggest deposition by a coarse-grained meandering river.
A detailed analysis of the relation between the depositional surface and the fabric of pebbles in planar crossbeds indicates downstream rather than lateral accretion. In fact, the dip of the intermediate axis of the pebbles parallels the foreset dip. Such a feature and the basin-wide divergence between trough and planar cross-stratification suggests deposition by lateral-diagonal bars in a low-sinuosity river.
The Pleistocene fluvial deposits of the Valdarno basin have a facies association and sedimentary structures similar to modern low-sinuosity rivers of the Northern Apennines.
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Recent Developments in Fluvial Sedimentology
This volume brings together 36 of the manuscripts that were presented at the Third International Fluvial Sedimentology Conference hosted by Colorado State University in August, 1985. Fluvial systems and sedimentary rock sequences discussed range in age from Holocene to Precambrian and include many diverse areas. The principal objective of the volume was to document the recent developments in the application of facies analysis to the reconstruction of the architecture of fluvial systems. Reconstruction of architecture is an integral part of the overall process of basin analysis.