Late Weichselian and Holocene sedimentary processes and glacier dynamics in Woodfjorden, Bockfjorden and Liefdefjorden, North Spitsbergen

Abstract

Abstract Swath bathymetry, high resolution seismic data and sediment cores were analyzed to reconstruct the Late Weichselian and Holocene sedimentary environments and glacier dynamics in Woodfjorden, Bockfjorden and Liefdefjorden, north Spitsbergen. Mega-scale glacial-lineations provide evidence of fast-flowing grounded ice draining the northwestern parts of the Late Weichselian Svalbard Barents Sea Ice Sheet. Numerous recessional moraines suggest that the deglaciation of the study area occurred stepwise, whereas the deep outer parts of Woodfjorden were deglaciated relatively rapidly (up to ~200 m/yr). The ice fronts retreated slower (~160 m/yr to 50 m/yr) in the shallower middle and inner parts. Suspension settling, as well as ice-rafting from icebergs and sea-ice, are the dominating sedimentary processes. Ice-rafting becomes of relative higher importance with increasing distance from the fjord heads. Sediment supply from tidewater glaciers has a large influence in Liefdefjorden, suspension settling from glacifluvial runoff is higher in inner Woodfjorden and in Bockfjorden. The core data show a strong correlation of color and geochemical properties so that these proxies can be applied to study the influence of sediment sources on the study area over time. Red and Ca-rich sediments are indicative for sediments derived from Woodfjorden; brownish and Fe-rich sediments are characteristic proxies for sediment from Liefdefjorden. Enhanced ice-rafting and dominant sediment delivery from Woodfjorden occurred between ~13,350 and ~13,200 cal. yr. BP. This was followed by an increase in sediment supply from Liefdefjorden until ~12,800 cal. yr. BP. Decreasing ice-rafting, likely related to increased sea-ice cover and cooler surface conditions, occurred from ~12,800 to 12,100 cal. yr. BP. This might be related to climatic cooling during the Younger Dryas. A peak in IRD around ~10,000 cal. yr. BP is inferred to indicate the final phase of deglaciation in Woodfjorden. Increases in ice-rafting from icebergs and sea-ice between ~6200 and ~5000 cal. yr. BP are probably related to a regional cooling. Reduced ice rafting occurred repeatedly during the last ~4000 years, most probably related to the ongoing cooling. The sediment derived mainly from Liefdefjorden. However, periods of enhanced ice-rafting occurred repeatedly until ~1500 cal.