University of Cambridge > > Scott Polar Research Institute - Physical Sciences Seminar > Submarine canyons in polar and temperate margins: shaping mechanisms and long-term evolution

Submarine canyons in polar and temperate margins: shaping mechanisms and long-term evolution

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Submarine canyons are deep incisions observed along most of the world’s continental margins. Their topographic relief is as dramatic as that of any canyon or river valley on land but is hidden beneath the surface of the ocean. Our knowledge of canyons has therefore come primarily from remote sensing and sampling, and has involved contributions from various oceanographic disciplines. Canyons represent a critical link between coastal and shelf waters and abyssal depths; water masses, sediment, nutrients, and even litter and pollutants are carried through them. Advances in technology continue to provide new insights into canyon environments by pushing the frontier of deep marine observations and measurements. In this talk we will describe the main geomorphic features of submarine canyons and what is known about their formation and the fundamental processes controlling their long-term form and dynamics. We will present a simple model for the long-profile curvature of submarine canyons, inspired in fluvial systems, that includes the combined effects of turbidity currents and background (i.e. hemipelagic) sedimentation, and compare the range of model profile shapes with those observed in present-day continental slopes, 3D seismic data and experimental models. Finally we will introduce a relatively poorly known geomorphic agent in submarine slopes: the cascading of dense shelf waters. This oceanographic phenomenon occurs seasonally and only in certain polar and temperate margins through cooling, evaporation, sea-ice freezing and/or deep sub-ice shelf melting. It involves the massive transfer of energy and matter from shallow to deep waters and can result in appreciable sediment erosion and downslope transport. We will discuss about the distribution and hydrodynamics of these flows, its far-reaching effects on the seafloor relief, and whether it should be included in the classic turbidity current and mass-gravity transport continuum of processes and deposits formulated more than 70 years ago.

This talk is part of the Scott Polar Research Institute - Physical Sciences Seminar series.

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