Modelling late Cenozoic isostatic elevation changes in Storfjorden, NW Barents Sea: an indication of varying erosional regimes

Storfjorden Fan off NW Barents Sea contains similar to 116 x 10(3) km(3) of sediments which are interpreted to have been derived from a drainage area measuring 69 x 10(3) km(2) during the last ca. 2.3 m.y. Published isopach m aps of the Storfjorden deposits have been used in a numerical model to simu late late Cenozoic isostatic elevation changes in the Storfjorden drainage area. The volume estimates in the depositional area for various time interv als together with the corrected density estimates for the eroded sediments indicate that similar to 1100 m of sediments have been eroded from the drai nage area during the past ca. 2.3 m.y. The results of isostatic modelling s how three distinct topographic phases during this time: a subaerial phase ( 2.3-1.4 Ma), a transition phase (1.4-0.8 Ma) and a submarine phase (0.8 Ma- present). In addition, sediment yield values from the drainage area during various intervals have been calculated. Highest sediment yield values are o btained for the subaerial phase while those for the submerged phase are the lowest. The age estimates are somewhat uncertain, but based on the modelli ng results together with the estimates of sediment yield, it is suggested t hat the changes in elevation and sediment yield values can be linked to the documented late Cenozoic paleoclimatic shifts along the western Svalbard-B arents Sea Margin. The doubling of sediment yield in the 1.6-1.4 Ma time fr om the preceding 2.3-1.6 Ma interval, despite lower topography, is related to major ice expansion under a subaerial scenario. The lowest yield values during the past 0.8 m.y., despite repeated glacial advances, are attributed to submergence of the area below sea level such that periods of erosion we re limited to peak glacials with negligible erosion during the intervening interstadials and interglacials. (C) 2001 Elsevier Science B.V. All rights reserved.