A unique fine-grained sediment layer deposited west off Svalbard during the initial warming after the Last Glacial Maximum (Bølling/Allerød)

Christian.Hass [ at ] awi.de


The study aims to elucidate the processes that caused the deposition of a unique fine-grained sediment layer at the onset of the last deglacial basically along the western Svalbard margin and the western Yermak Plateau. Grain-size analyses of 11 sediment cores west and north off Svalbard and the Yermak Plateau reveal an exceptionally fine-grained sediment layer that was deposited within a relatively short period of ~300 years during the Bølling interstadial. The layer was found in cores located below the West Spitsbergen Current (WSC) that conveys Atlantic (AW) and mixed water masses northwards along the continental slope. The mixed waters are underlain by Norwegian Sea Deep Water (NSDW, water depth > 1000 m). North of Svalbard the upper 500 m (sill depth) branch off and flow in easterly direction to form the Svalbard Branch of the WSC. Further north the Yermak Slope Current (YSC, water depth: 1000 to 1500 m) advects NSDW towards the Arctic Ocean where it quickly loses its signature north of the Yermak Plateau. The studied fine-grained layer reveals a sortable-silt mean grain size of 15 to 20 µm. The fineness of this layer is basically the result of a coarse-silt subpopulation between 36 and 63 µm that is absent in this layer but present throughout most of the cores. As yet the sediment layer was found in 32 sediment cores (mostly published data) from ~75°N to ~82°N at water depths ranging from ~300 m (Kveithola) to 1880 m (Yermak slope) south, west and north of Svalbard. Very low magnetic susceptibility, a distinct decrease in Ca-ratios and slightly increased Ti-ratios are further key characteristics for the investigated layer (XRF analyses of 4 cores). AMS age determinations of another 4 cores show a doubled to ten-fold increased sedimentation rate for the period of deposition of this layer. The greatest thickness of the fine-grained layer appears in sediment cores from ~1400 to ~1500 m water depth and decreases in cores deeper than ~1600 m and cores shallower than ~1100 m water depth (except for Kveithola), respectively. Thus, the fine-grained material was transported northwards in a relatively narrow strip along the western Svalbard and Yermak slopes. The distribution and thickness of the investigated sediment layer can be linked to both, the rapid melting of the Svalbard and the Barents Sea ice sheets in response to the intense warming at the onset of the Bølling period. Since Kveithola trough is assumed to be fully deglaciated since 14.7 cal. years BP a sediment source in the adjacent Barents Sea as well as from local fjords of Spitsbergen is likely. Reference for the oceanographic information: Schlichtholz and Houssais, 1999.

Item Type
Conference (Talk)
Publication Status
Event Details
25th International Polar Congress, 17 Mar 2013 - 22 Mar 2013, Hamburg.
Eprint ID
Cite as
Schiele, K. , Hass, H. C. and Forwick, M. (2013): A unique fine-grained sediment layer deposited west off Svalbard during the initial warming after the Last Glacial Maximum (Bølling/Allerød) , 25th International Polar Congress, Hamburg, 17 March 2013 - 22 March 2013 .


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