THE NORWEGIAN–GREENLAND SEA CONTINENTAL MARGINS: MORPHOLOGY AND LATE QUATERNARY SEDIMENTARY PROCESSES AND ENVIRONMENT

Abstract

The continental margins surrounding the Norwegian–Greenland Sea are to a large degree shaped by processes during the late Quaternary. The paper gives an overview of the morphology and the processes responsible for the formation of three main groups of morphological features: slides, trough mouth fans and channels. Several large late Quaternary slides have been identified on the eastern Norwegian–Greenland Sea continental margin. The origin of the slides may be due to high sedimentation rates leading to a build-up of excess pore water pressure, perhaps with additional pressure caused by gas bubbles. Triggering might have been prompted by earthquakes or by decomposition of gas hydrates. Trough mouth fans (TMF) are fans at the mouths of transverse troughs on presently or formerly glaciated continental shelves. In the Norwegian–Greenland Sea, seven TMFs have been identified varying in area from 2700 km 2 to 215 000 km 2. The Trough Mouth Fans are depocentres of sediments which have accumulated in front of ice streams draining the large Northwest European ice sheets. The sediments deposited at the shelf break/upper slope by the ice stream were remobilized and transported downslope, mostly as debris flows. The Trough Mouth Fans hold the potential for giving information about the various ice streams feeding them with regard to velocity and ice discharge. Two large deep-sea channel systems have been observed along the Norwegian continental margin, the Lofoten Basin Channel and the Inbis Channel. Along the East Greenland margin, several channel systems have been identified. The deep-sea channels may have been formed by dense water originating from cooling, sea-ice formation and brine rejection close to the glacier margin or they may originate from small slides on the upper slope transforming into debris flows and turbidity currents.