Sedimentary environments in the south-western Barents Sea during the last deglaciation and the Holocene: a case study outside the Ingøydjupet trough

Abstract

A lithological and foraminiferal study of newly acquired sediment cores outside the Ingøydjupet (Ingøy Deep) trough has been carried out to improve constraints on the last deglacial history in the south-western Barents Sea. Three lithofacies and three foraminiferal facies were identified. The lowermost lithological unit is a diamicton interpreted as glacial till. It contains a low-abundance, ecologically mixed foraminiferal assemblage, presumably resulting from glacial reworking. Above the diamicton, a layer of ice-rafted debris (IRD), likely associated with intensive iceberg production, marks the initial destabilization of the marine-based ice sheet. At this time, ca. 15.6–15.0 Ky B.P., opportunistic foraminiferal species Nonionellina labradorica and Stainforthia spp. reached peak abundance. During the south-western Barents Sea ice-margin retreat, presumably corresponding to the Bølling interstadial, a sequence of glaciomarine laminations was deposited conformably on the layer of IRD. Sedimentation rates were apparently high (estimated about 0.4 cm per year) and the foraminiferal fauna was dominated by Elphidium spp. and Cassidulina reniforme, species common for glacier-proximal environments. A hiatus at the top of the deglacial unit is likely linked to the high bottom-current activity associated with a strengthened inflow of Atlantic water masses into the Barents Sea. The uppermost lithological unit is represented by the Holocene marine sandy mud. It contains a high-abundance, high-diversity foraminiferal fauna with common cassidulinids, Cibicides spp., Epistominella pusilla and planktic species.

• Deglaciation
• Barents Sea ice sheet
• sediment cores
• lithofacies
• biozonation.

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Acknowledgements

Harald Brunstad and Lundin Petroleum Norway are warmly thanked for financial support and for providing the cores. For the excellent support during the expedition, a sincere gratitude goes to Arnfinn Karlsen, Helge Jubskås, Martin Syre Wiig, Kjetil Bergh Ånonsen and Jon Otto Buer from the Norwegian Defence Research Establishment, as well as to the officers and crew of RV H.U. Sverdrup II, Johnny Remøy (captain), Terje Haugen, Erling Olsen, Henning Bergsnes, John Johnsen, Bernt Nilsen and Liv Sørensen. Arnfinn Karlsen is thanked also for the logistical assistance. Haflidi Haflidason at the University of Bergen is gratefully acknowledged for the assistance with core logging. Knut Dalen at the Norwegian University of Life Sciences is thanked for assistance with CT scanning, and Mufak Naoroz at the University of Oslo for support with grain size analysis. The article benefited from comments and suggestions by Leonid Polyak and other reviewers.

Notes

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