Thursday, 30 August 2007 - 11:30 AM
4.A.A-5
Six million years of environmental (glacial—interglacial) conditions preserved in volcanic lithofacies of the James Ross Island Volcanic Group, northern Antarctic Peninsula
John L. Smellie1, Anna E. Nelson1, Joanne S. Johnson1, J.S. Johnson1, William C. McIntosh2, Richard Esser2, Magnus T. Gudmundsson3, Michael J. Hambrey4, and Ben van Wyk De Vries5. (1) Geological Sciences Division, British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, United Kingdom, (2) Department of Earth and Environmental Sciences, New Mexico Tech, 801 Leroy Pl, Socorro, NM 87801, (3) Science Institute, University of Iceland, Hofsvallagata 53, Reykjavik, 107, Iceland, (4) Institute of Geography & Earth Sciences, University of Wales, Ceredigion, Aberystwyth, United Kingdom, (5) Departement des Sciences de la Terre, Universite Blaise Pascal, 5 Rue Kessler, Clermont-Ferrand, France
The Neogene geological record in the James Ross Island region is dominated by persistent basaltic volcanism. At least 50 mainly effusive basaltic volcanic eruptions constructed an extensive volcanic field over a 6 million year period. Interpretation of the volcanic units has enabled critical parameters of the palaeo-ice cover to be deduced for the first time, for multiple time slices. Most eruptions took place within a relatively thin glacier cover, typically just 200-350 m, with fewer periods of thicker ice, c. 600-750 m. The glacier cover increased in thickness toward the present, but there is no evidence for a “giant” ice sheet. It was probably sub-polar (polythermal) with a low profile dominated by a local ice cap on James Ross Island. These results are the first evidence for the morphology, thickness and thermal regime of the glacier cover in the northern Antarctic Peninsula region for the late Neogene period.