Tuesday, 28 August 2007 - 11:10 AM
2.A.A-4
Does the Late Pliocene change in the architecture of the Antarctic margin correspond to the transition to the modern Antarctic Ice Sheet?
Michele Rebesco, RIMA, stituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), Borgo Grotta Gigante 42/C, Sgonico (TS), Italy and Angelo Camerlenghi, ICREA, Istitució Catalana de Recerca i Estudis Avançats c/o GRC Geociències Marines, Departament d'Estratigrafia , Paleontologia i Geociències Marines, Universitat de Barcelona / Facultat de Geologia, C/ Martí i Franquès, s/n, Barcelona, Spain.
In six widely-spaced key sectors of the Antarctic continental margin (Antarctic Peninsula; Prydz Bay; Weddell Sea; Wilkes Land; east and west Ross Sea), we observe a change in the geometry of the sedimentary deposits which is characterized by: margin-wide erosion and subsequent progradation on the continental shelf; downlap on the continental slope; and major mass-wasting deposits on the continental rise. The change occurs in the late Neogene in all sectors, although there are minor variations in this timing, and the stratigraphic position on the margin is not always obvious. The change is dated at about 3 Ma in the Antarctic Peninsula and Prydz Bay sectors and is broadly concomitant in the other sectors. This suggests a common driving force, which we suggest was the transition of the Antarctic ice sheet regime from polythermal conditions to the present polar cold, dry-based conditions.