Shelf and Slope Sedimentation in the Arctic Ocean: Comparison of the Alaskan Margin with Deep-Sea Sediments; Drift Deposits and the Role of Sea Ice

A study of several cores from the outer shelf and continental slope north of Alaska indicate that localized drift deposits occur here with sedimentation rates of more than 1.5m/kyr during the Holocene. Currents in this area average about 5-20 cm/s but can reach 100 cm/s and these are certainly capable of entraining even cohesive sediment on the inner and mid-shelf or from the slope and depositing it where eddies or bottom topography causes separation of flow such as in canyons. Unlike most textural investigations of Arctic sediment that focus on the coarser ice-rafted detritus (IRD), this paper focuses on the greater than 95% of the sediment finer than 45 microns. The mean size of this fraction varies between 6 and 15 microns in several Holocene core sections with the higher values closer to shore. Analysis of detailed size distributions of these Holocene deposits are compared to 34 sea ice samples collected across the Arctic Ocean and to Holocene sediment from central Arctic cores and indicate that similar textural parameters occur in all of these sediments with the finest sediments on the central Arctic ridges. Principal components of these size distributions indicate that sea ice is an important link between the shelves and the central Arctic. Factor scores provide new insights into the processes of transport and deposition in the Arctic.