Quaternary sediments and environments on the continental shelf off northern Norway

Abstract

Based on lithologic, palaeontologic and chronostratigraphic investigations of close to 200 gravity cores from troughs, deep banks and shallow banks the following late Quaternary environment can be outlined: In the Weichselian, deposition of basal tills was followed by deposition of laminated clay in a sea-ice environment. Later a pebbly pelite was deposited in the troughs at the same time as the banks were iceberg ploughed. Then (13,000 yrs B.P.) a period with incipient winnowing occurred on the deep banks and deposition of sandy pelite took place in the troughs. The Holocene commenced with a marked environmental change due to intrusion of Atlantic water, the fauna changed from arctic to boreal, high-energy winnowing forming a lag deposit took place on the banks, and high accumulation rates in the troughs occurred due to the winnowing and sediment influx from the downwasting continental icesheet. During the later part of the Holocene the winnowing diminished on the deeper banks, on the shallow banks and on the shelf break it still prevails, and in the troughs calcareous sandy mud is being deposited. The surface sediments comprise three main facies, bouldery and pebbly sand, sand, and sandy mud, whose distribution mainly depends on the prevailing bottom current regime. The composition of the older Quaternary sediments is demonstrated by some selected seismic profiles.