Mechanisms of sediment transport and dispersion in a tectonically active submarine valley/canyon system: Zakynthos Straits, NW Hellenic Trench

Abstract

Physical oceanographic and geophysical data sets are used to examine sediment transport processes. Currents were directed generally along the axis of the valley/canyon system and, in an area of low tidal range, are attributed to regional weather patterns. Near-bed and near-surface currents are opposed, both in terms of instantaneous observations and net (Lagrangian) drift. Near-bed down-canyon water movement provides a mechanism for the offshore movement of fine-grained sediment. Slope failures have been identified in the geophysical records and are considered to be controlled by earthquakes and salt diapirism, in a tectonically active area. These failures, as mass displacement or slow down-slope creep, result in debris infill and the generation of turbidity currents. Fine-grained sediments, resuspended by the turbidity currents, would be transported down-canyon by the slowly moving near-bed residual water movement. Hence, the dominant transport mechanisms in the valley/canyon system are: (1) frequent mass sediment failure; and (2) nearly continuous down-channel fine-grained suspended sediment movement.