LATE CENOZOIC SEISMIC STRATIGRAPHY AND GLACIAL GEOLOGICAL DEVELOPMENTOF THE EAST GREENLAND AND SVALBARD BARENTS-SEA CONTINENTAL MARGINS

The European program on the Late Cenozoic evolution of the Polar North Atlantic Margins (PONAM), running from 1990 to 1994, resulted in a we alth of seismic data and sediment cores, particularly from the Svalbar d and Parents Sea continental margin, but also from areas of the East Greenland margin. Deep sediment coring was undertaken on both margins during ODP Legs 152 and 162. This payer uses the PONAM-generated infor mation as well as previous and subsequent seismic and core data, to re view our present understanding of the glacial geological development o f these regions. Four main depositional facies have been identified. T hese are represented by hemipelagic, glaciomarine sediments, sandy, si lty debris flows, diamictic debris flows and tills deposited directly beneath grounded ice. The temporal and spatial distribution of these f our facies determines the architecture and seismic character of the tw o continental margins. The two regions show significant differences, w ith regard to both the timing of initial glaciation and the response o f the ice sheets to climatic variability. Glacial deposition has taken place on the East Greenland margin at least since 7 Ma, but apparentl y only since 2.5 Ma on the Svalbard-Barents Sea margin. Significant gl acial expansion across the continental shelf probably occurred in the early and late Pliocene in East Greenland, whereas the glaciers on Sva lbard and the Barents Sea did not reach the shelf edge until the early Pleistocene. Despite a shorter glacial period, average glacial sedime ntation rates are 2-3 times higher on the Svalbard-Barents Sea margin than on the studied parts of the East Greenland margin. The Svalbard-B arents Sea ice sheet has advanced and retreated much more frequently d uring the Plio-Pleistocene than the Greenland ice sheet. Glacial regim e (polar on Greenland and polythermal to temperate in Svalbard and the Barents Sea) and the more easily erodible preglacial bedrock of Svalb ard and the Barents Sea are thought to be main factors responsible for the differences in ice sheet behavior and, consequently, glacial sedi ment production. (C) 1998 Elsevier Science Ltd. All rights reserved.