CENOZOIC SEDIMENTATION ALONG THE SOUTHWESTERN BARENTS SEA MARGIN IN RELATION TO UPLIFT AND EROSION OF THE SHELF

The distribution of Cenozoic sediments along the southwestern Barents Sea margin reflects the progressive opening of the Norwegian-Greenland Sea towards the north, The Lofoten Basin fill consists of Early to Mi ddle Tertiary mostly undeformed sequences of great lateral extent, ove rlain by a huge sedimentary wedge which extends over both continental and oceanic crust. This wedge, the Bjornoya Fan, comprises 3-4 lan of Late Cenozoic deposits. Regional seismic lines enable tracing of seque nce boundaries westward until they terminate onto oceanic basement of known age, thus providing maximum ages of the sediments above, Additio nal age constraints come from exploration wells and shallow boreholes in the southwestern Barents Sea as well as paleoenvironmental indicato rs from deep sea drilling, The pre-glacial units (sequences Tel-Te4) a re controlled by the plate tectonic setting and basin geometry at the time of deposition. The seismic stratigraphy of the Bjornoya Fan (refl ectors R1-R7) indicates three main phases of glacial erosion and sedim entation: (1) 2.3 Ma (R7) dates the onset of extensive continental she lf glaciations, (2) 1.0 Ma (R5) marks an increase in the intensity of glaciations, giving rise to increased accumulation rates and the onset of large-scale mass movements and (3) 0.44 Ma (R1) marks the end of n et erosion in the outer parts of the Bjornoya Trough. The wedge repres ents about 70% of the sediments in the Lofoten Basin and its young age indicates that a large thickness of sedimentary strata has been erode d and deposited over a short geological time period. Using volumetric calculations, Cenozoic erosion and sedimentation rates have been quant ified. Furthermore, the sediment yield and denudation rates for the ma in glacial sequences in the Bjornoya Fan are calculated.