Reconstructions of paleoceanography and ice retreat based on benthic foraminifera, stable isotopes and sedimentological investigations from the northwestern Barents Sea south of Nordaustlandet, Svalbard

Abstract

One gracity core NP05–11–49GC was retrieved from a 320 m water depth in the central part of Erik Eriksen Strait, south of Nordaustlandet, northwestern Barents Sea. The core was investigated for benthic foraminiferal distribution patterns, stable isotopes and sedimentological parameters in order to reconstruct the Late Weichselian deglaciation and Holocene paleoenvironment and paleoceanography of the Erik Eriksen Strait. Two additional cores, NP05–11–84GC2 from southwestern Erik Eriksen Strait and NP05–11–51GC2 from the southern head of the Kvitøya Trough, were investigated for sedimentological parameters. The results show that the deglaciation of the Erik Eriksen Strait and Kvitøya Trough was rapid and commenced at 14 100 cal. yr BP. This resulted in the deposition of loose diamicts due to heavy rainout of IRD from released icebergs of the retreating Svalbard-Barents Sea Ice Sheet (SBIS). Continued melting of the SBIS during the Bølling– Allerød interstadials between 14 100 and 12 700 cal. yr BP occurred through the release of sediment-laden meltwater plumes resulting in deposition of laminated sediments. Harsh glaciomarine conditions with increased sea ice cover characterized the Younger Dryas cooling (12 700 –11 950 cal. yr BP). Occasional ice rafting shows that the Erik Eriksen Strait also experienced periods with seasonally open waters during the cooling. The transition to the Early Holocene warming happened in two steps between 11 960 – 11 290 and 11 020 – 10 750 cal yr. BP, interrupted by the Pre-Boreal Oscillation. The glacio-isostatically suppressed sea floor caused an over-deepening of the area and a deeper paleo sea level. Strong inflow of subsurface Atlantic water caused an amelioration of the environmental conditions and very high biological activity. A relatively cool Early Holocene Climatic Optimum characterized the foraminiferal fauna of the Erik Eriksen Strait, which reflected that the east-west climatic gradient observed today also existed in the Early Holocene. An abrupt cooling, along with a decrease of salinity showed a weakening of the Atlantic water inflow at 8300 cal. yr BP until 7600 cal. yr BP. Thereafter, a deterioration of the environment occurred with a stronger dominance of Arctic waters and increased ice rafting. The study show that the high isostatically rebound of the area have affected the inflow of Atlantic water to the northwestern Barents Sea corner and must be considered when reconstructing the areas paleooceanography. The data from Erik Eriksen Strait generally display regional changes that are correlative with studies from the Svalbard-Barents Sea area. It suggests that an east-west climatic gradient, similar to today, existed between eastern and western Svalbard in the Early Holocene.