Seafloor morphology and acoustic facies of the George V Land shelf

Abstract

To study the seafloor morphology on the George V Land shelf, East Antarctica, over 2000km of high-frequency 3.5-27 kHz, echo-sounder data were collected between February and March 2000. The shelf can be divided into four acoustic facies: (a) Type IA-2 seabed is ice-keel turbate found on mid- to outer-shelf banks on seafloor less than 500m deep; (b) Type IB seabed is siliceous mud and diatom ooze drift, drape and fill deposits within the George V Basin between 750 and 850m depth; (c) Type IIB seabed is smooth diamicton below 500m depth, and occasionally has lowrelief megaflutes or ridge and swale features; (d) Type IIIC seabed is high relief ridges and canyons from the coast to the deepest part of the George V Basin. The acoustic facies are explained in terms of glacial and oceanographic influences on the shelf since the Last Glacial Maximum.