Glacial processes and large-scale morphology on the mid-norwegian continental shelf

Abstract

A regional digital bathymetric data set covering most of the mid-Norwegian continental shelf is presented and gives a unique regional view into glacial processes and ice-sheet dynamics on this part of the continental shelf during the Weichselian, indicating that forms and deposits were created by a highly dynamic ice sheet. At times, ice flow was mainly channelised through ice streams located in bathymetric depressions on the shelf areas. Glacial sedimentary processes are discussed with a focus on the marine-based part of the Scandinavian ice sheet during the last glaciation (the Weichselian). Ice sheets that grounded on the shelf edge are thought to have been responsible for depositing complex prograding sequences on the mid-Norwegian shelf during several glaciations from Late Pliocene time, reaching a maximum thickness of 1500 m on the shelf edge. During interglacials, the shelf areas were sediment-starved with little or no clastic sedimentation. On top of these prograding units, several packages of Quaternary sediments (mainly till of Weichselian age) show a more aggradational pattern. Improved knowledge about the deposition and age of the upper Cenozoic sediment wedge has proved vital for revealing the ice-sheet dynamics and may also be important in understanding the maturation and migration of hydrocarbons on the mid-Norwegian shelf.