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SUMMARY:Submarine canyons in polar and temperate margins: shaping mechanis
 ms and long-term evolution - Dr. David Amblas\, Scott Polar Research Insti
 tute\, University of Cambridge
DTSTART:20170301T163000Z
DTEND:20170301T173000Z
UID:TALK71134@talks.cam.ac.uk
CONTACT:Ian Willis
DESCRIPTION:Submarine canyons are deep incisions observed along most of th
 e 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 surfa
 ce of the ocean. Our knowledge of canyons has therefore come primarily fro
 m remote sensing and sampling\, and has involved contributions from variou
 s oceanographic disciplines. Canyons represent a critical link between coa
 stal and shelf waters and abyssal depths\; water masses\, sediment\, nutri
 ents\, and even litter and pollutants are carried through them. Advances i
 n 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 a
 nd what is known about their formation and the fundamental processes contr
 olling their long-term form and dynamics. We will present a simple model f
 or the long-profile curvature of submarine canyons\, inspired in fluvial s
 ystems\, that includes the combined effects of turbidity currents and back
 ground (i.e. hemipelagic) sedimentation\, and compare the range of model p
 rofile shapes with those observed in present-day continental slopes\, 3D s
 eismic data and experimental models. Finally we will introduce a relativel
 y poorly known geomorphic agent in submarine slopes: the cascading of dens
 e shelf waters. This oceanographic phenomenon occurs seasonally and only i
 n certain polar and temperate margins through cooling\, evaporation\, sea-
 ice freezing and/or deep sub-ice shelf melting. It involves the massive tr
 ansfer of energy and matter from shallow to deep waters and can result in 
 appreciable sediment erosion and downslope transport. We will discuss abou
 t the distribution and hydrodynamics of these flows\, its far-reaching eff
 ects on the seafloor relief\, and whether it should be included in the cla
 ssic turbidity current and mass-gravity transport continuum of processes a
 nd deposits formulated more than 70 years ago.
LOCATION:Scott Polar Research Institute\, main lecture theatre
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