Cenozoic erosion and sediment yield in the drainage area of the Storfjorden Fan

The western Barents Sea continental margin, between 74° and 77°N, comprises 7–8 km post-Paleocene sediments. The margin sediments have been divided into four seismic sequences dated by seismic correlation to adjacent areas. This chronostratigraphy shows that the uppermost three sequences are of glacial origin, deposited during the last 2.3 m.y. A huge sedimentary wedge, the Storfjorden Fan, was deposited in front of the Storfjorden Trough between 2.3 and 0.44 Ma, whereas during the last 0.44 m.y. a more evenly distribution pattern is observed. The outbuilding of the fan is related to the onset of the northern hemisphere glaciations causing intense glacial erosion of predominantly consolidated rocks. Seismic facies interpretations indicates that the fan outbuilding was connected to large-scale mass movements. Within the uppermost part of the glacial sequence parallel and continuous reflectors and locally disturbed pattern on the upper slope are associated with downslope change in facies. Volumetric calculations, based on velocity studies and isopach maps, have been used to quantify Cenozoic erosion, sediment yield, sedimentation and erosion rates. Approximately 3300 m of post-Paleocene erosion is calculated within the drainage area of the Storfjorden Fan, of which about 1700 m was eroded in late Pliocene-Pleistocene times giving an average denudation rate of 0.63 mm/yr.