Pattern and timing of the northwestern Barents Sea Ice Sheet deglaciation and indications of episodic Holocene deposition

Abstract

The origin of two acoustic sediment units has been studied based on lithological facies, chronology and benthic stable isotope values as well as on foraminifera and clay mineral assemblages in six marine sediment cores from Kveithola, a small trough west of Spitsbergenbanken on the western Barents Sea margin. We have identified four time slices with characteristic sedimentary environments. Before c. 14.2 cal. ka, rhythmically laminated muds indicate extensive sea ice cover in the area. From c. 13.9 to 14.2 cal. ka, muds rich in ice‐rafted debris were deposited during the disintegration of grounded ice on Spitsbergenbanken. From c. 10.3 to 13.1 cal. ka, sediments with heterogeneous lithologies suggest a shifting influence of suspension settling and iceberg rafting, probably derived from a decaying Barents Sea Ice Sheet in the inner‐fjord and land areas to the north of Kveithola. Holocene deposition was episodic and characterized by the deposition of calcareous sands and shell debris, indicative of strong bottom currents. We speculate that a marked erosional boundary at c. 8.2 cal. ka may have been caused by the Storegga tsunami. Whilst deposition was sparse during the Holocene, Kveithola acted as a sediment trap during the preceding deglaciation. Investigation of the deglacial sediments provides unprecedented details on the dynamics and timing of glacial retreat from Spitsbergenbanken.

Reconstruction of Atlantic water variability during the Holocene in the western Barents Sea

“…1). The lithology of KA11 was previously described by Rüther et al (2012). The present study focuses on the upper 130 cm of the core.…”

“…A standard reservoir correction of 400 yr and regional R value of 67 ± 34 (Mangerud and Gulliksen, 1975) was used. Dates marked with * are from Rüther et al (2012 species Cassidulina neoteretis. The δ 18 O c values were corrected for disequilibrium with seawater by +0.02 ‰ (Poole, 1994) and corrected for the ice-volume effect, where a sea-level change of 10 m corresponds to a 0.11 ‰ isotopic change (Fairbanks, 1989).…”

“…All results are reported in ‰ Vienna Pee Dee Belemnite (V-PDB). Thirteen radiocarbon dates were obtained using accelerator mass spectrometry (Table 1); eight dates were previously published (Rüther et al, 2012). The radiocarbon dates were measured on mollusks and monospecific samples of benthic Foraminifera (Table 1).…”

“…1). It is a 100 kmlong east-west trending trough, 15-20 km-wide with a water depth ranging from 200 to 400 m (Rüther et al, 2012). At present, the Barents Sea is influenced by three main water masses: Atlantic water, Arctic water and coastal water.…”

“…We studied a sediment core retrieved from the relatively small Kveithola Trough located at the western Barents Sea margin. The trough has acted as a natural sediment trap and holds 130 cm of Holocene sediments, allowing for a sampling resolution at decadal to centennial timescales (Rüther et al, 2012). At present, the study area is dominated by Atlantic water masses (Berben et al, 2013) and is located close to the Arctic front.…”