LATE CENOZOIC EVOLUTION OF THE WESTERN BARENTS SEA SVALBARD CONTINENTAL-MARGIN

Seven regionally correlatable reflectors, named R7 (oldest) to R1, hav e been identified in the Upper Cenozoic sedimentary succession along t he western continental margin of Svalbard and the Barents Sea. Regiona l seismic profiles have been used to correlate between submarine fans that comprise major depocentres in this region. Glacial sediment thick nesses reach up to 3 seconds two-way time, corresponding to 3.5-4 km. Despite limited chronostratigraphic control, ages have been assigned t o the major sequence boundaries based on ties both to exploration well s and to shallow boreholes, and by paleoenvironmental interpretations and correlations with other regions. Lateral and vertical variations i n seismic facies, between stratified and chaotic with slump structures , have major implications for the interpretation of the depositional r egime along the margin. The main phases of erosion and deposition at d ifferent segments of the margin are discussed in the paper, which also provides a regional seismic stratigraphic framework for two complemen tary papers in the present volume. Reflector R7 marks the onset of ext ensive continental shelf glaciations, but whereas the outer Svalbard s helf has been heavily and frequently glaciated since R7 time, this did not occur, or occurred to a much less extent, until R5 time in the so uthern Barents Sea. The present study provides the background for a qu antification of the late Cenozoic glacial erosion of Svalbard and the Barents Sea. The rates of erosion and deposition exhibit large tempora l and spatial variations reflecting the importance of glacial processe s in the Late Cenozoic development of this nearly 1000 km long margin.