Description: The southwestern Barents Sea has experienced profound erosion during the last ∼2.7 m.y. that has resulted in the development of a characteristic glacial morphology of the continental shelf and deposition of a several-kilometer-thick sediment fan along the western margin prograding into the deep sea. In the period from ca. 2.7 to 1.5 Ma, proglacial processes, including fluvial and glaciofluvial erosion, dominated. For this period, the total average erosion of the shelf was 170–230 m, the average erosion rate was 0.15–0.2 mm/yr, and the average sedimentation rates on the fan were 16–22 cm/k.y. Subglacial erosion affected an area of ∼575,000 km2 during the period from ca. 1.5 to 0.7 Ma. Total average erosion is estimated at 330–420 m for this interval, and the average erosion rate was 0.4–0.5 mm/yr. Average sedimentation rates were 50–64 cm/k.y. During the last ∼0.7 m.y., glacial erosion mainly has occurred beneath fast-flowing paleo–ice streams topographically confined to troughs (∼200,000 km2). The total average erosion is estimated at 440–530 m, average erosion rate is 0.6–0.8 mm/yr, and average sedimentation rate on the continental slope is 18–22 cm/k.y. The amount of erosion was mainly determined by the duration of the glaciations and the location, velocity, and basal properties of the ice streams. In total, glacial erosion of the troughs has been relatively high throughout the last ∼2.7 m.y. at ∼1000–1100 m. For the banks, erosion is inferred to have increased from ca. 2.7 Ma to a peak between 1.5 and 0.7 Ma. Subsequently, little erosion occurred in these areas, which implies a total of 500–650 m of erosion. Compared with other high-latitude areas, our rates are among the highest so far reported. This comparison also demonstrates that there have been large variations in the rate of sediment delivery to the glaciated continental margins.

Description: A sediment core from the Lofoten Contourite Drift on the continental slope off Northern Norway, proximal to the former Vestfjorden-Trsnadjupet Ice Stream, details the development, variability and decline of marine margins of the northwestern Fennoscandian Ice Sheet during the time interval 25.3-14 cal ka BP, including the Last Glacial Maximum and onset of the deglaciation based on high-resolution IRD records. From the core interval between 25.3 and 17.7 cal ka BP we report data points with a mean time step of 10 years, between 17.7 cal ka BP and the Holocene time steps are typically 50 years. The core is divided into 7 informal ice-rafted debris (IRD) zones based on the variations in IRD including 7 major IRD maxima (A-G), inferred to represent periods of high iceberg production. Petrological identification reveals dominance of crystalline IRD (monocrystalline, plutonic and metamorphic rock fragments) accounting for 75-80% of total IRD assemblages, while sedimentary fragments generally account for 15-20%. The crystalline fragments (including eclogite and mangerite from a nearby terrestrial source) increase across the IRD peaks while the sedimentary fragments remain constant. This points to the importance of erosional products from icebergs originating from fast-flowing paleo-ice streams including the Vestfjorden-Trsnadjupet Ice Stream draining from the Fennoscandian mainland during the IRD maxima periods. Increased temperature of the adjacent surface water masses was probably an important external forcing factor on the Fennoscandian Ice Sheet behavior because some IRD maxima and plumite deposition from meltwater plumes post-date periods of increased sea surface temperatures. The peak IRD depositions occur in centennial and millennial time cycles (~200, 1030 and 3900 year) indicating some external forcing by solar variation. Both mechanisms could explain the observed synchronous instability of the northwestern Fennoscandian Ice Sheet to other European Ice Sheets.

Description: Multi-proxy analyses of six sediment cores and analyses of swath bathymetry and chirp data were integrated to elucidate the Holocene sedimentary processes and palaeoenvironments in Smeerenburgfjorden, northwest Spits- bergen. Three basins separated by two sills define the present-day large-scale bathymetry. A transverse ridge in the innermost part of the fjord represents the Little Ice Age (LIA) maximum position of Smeerenburgbreen. Slide scars along the fjord sides and mass transport deposits in the basins indicate repeated mass wasting. Recessional moraines deposited during the last deglaciation suggest a mean annual retreat rate of 140 m/year. Another set of recessional moraines deposited between the maximum LIA position of Smeerenburgbreen and its present day ter- minus indicate a mean retreat rate of the ice front of ∼87 m/year. Strong out-fjord decreasing trends in magnetic susceptibility and Fe-content indicate that these properties are related to material originating from the Horneman- toppen granite in the catchment of Smeerenburgbreen and are, thus, useful proxies for the reconstruction of the activity of the glacier. Relatively little ice rafting, most likely related to warmer surface water conditions, occurred between 8650 and 7350 cal. years BP. Ice rafting from both sea-ice and icebergs increased around 6200 cal. years BP and peaked at ∼5200 cal. years BP, associated with a regional cooling. Smeerenburgbreen became more active around 2000 cal. years BP. It probably retreated during the Roman Warm Period (50 BC – AD 400) and advanced during the Dark Ages Cold Period (AD 400 – 800). From AD 1300 – 1500 (late Medieval Warm Period), ice rafting, sedimentation rates and productivity increased in the inner fjord. The Little Ice Age was characterised by reduced ice rafting, possibly linked to an increased sea-ice cover suppressing iceberg drift. An increase in Ice Rafted Debris (IRD) commencing around AD 1880 is suggested to represent the beginning of Smeerenburgbreen’s retreat from its LIA maximum towards its present position.

Description: Swath-bathymetry, high-resolution seismics and lithological data from the Wijdefjorden-Austfjorden fjord system, the largest fjord system on northern Spitsbergen, have been analysed. The data indicate that multiple halts and/or readvances during the deglaciation of the study area at the end of the last glacial occurred. However, even though the study area and several west Spitsbergen fjords are fed by the same glacier source (the ice field Lomonosovfonna), the final deglaciation of Wijdefjorden-Austfjorden took place after 9300 cal. years BP, i.e. at least approx. 2000 years later than in the west. It is suggested that the retarded deglaciation of the study area is mainly related to the fjord bathymetry, i.e. a more than 35 km wide and up to 60 m high plateau in the central parts of the study area (approx. 45 km beyond the present fjord head). Multiple, relatively large and partly stacked moraine ridges and sediment wedges are suggested to reflect that the ice front retreated slowly across this shallow area and that repeated readvances occurred. The absence of larger sediment wedges in the deeper parts between the shallow area and the fjord head may indicate that the final retreat occurred rapidly.

Description: Swath bathymetry and seismic data reveal two slide scars providing evidence for large-scale mass-wasting on the continental slope off northwest Spitsbergen. The largest scar is approx. 35 km long, at least 16 km wide and located between 1300 and 3000 m water depth. The failure is assumed to be of a retrogressive nature, because it affected multiple stratigraphic levels up to at least 200 ms two-way-travel time (approx. 150 m) below the present seafloor. The second largest slope failure affected an area of at least 35 km length, up to 7 km width and 70 ms (approx. 55 m) thickness below 1400 m water depth. It cuts into the south-eastern sidewall of the largest scar between 2700 and 2800 m water depth and deposition of sediment lobes within the largest scar occurred. The bathymetry within this slide scar is relatively smooth compared to the largest scar, but single blocks are visible. These observations suggest a retrogressive configuration of this slide, too. Minor failures along the side walls occur. Both slide scars are filled in with approx. 15 m of acoustically stratified sediments, suggesting that the slope failures occurred almost synchronously. However, the sediment lobes beyond the lower limit of the second largest slide scar suggest that this slide occurred after the largest slide. The slides were most probably triggered by seismic activity leading to failure within contouritic sediments.

Description: North and west Spitsbergen fjords acted as pathways for fast-flowing ice streams during the last glacial (e.g. Ottesen et al., 2005). The deglaciation of west Spitsbergen fjords occurred stepwise and the ice retreat terminated around 11,200 cal. years BP (calendar years before the present; e.g. Forwick & Vorren, 2009, 2011, and references therein; Baeten et al., 2010). However, the deglaciation dynamics and chronology of north Spitsbergen fjords still remain poorly understood. We present swath-bathymetry, high-resolution seismic data and two sediment cores from the approx. 110 km long, N-S oriented Wijdefjorden-Austfjorden fjord system, the largest fjord system on northern Spitsbergen. The data indicate that – as in the fjords on west Spitsbergen – multiple halts and/or readvances interrupted the retreat of the ice front during the final phase of the last glacial. However, even though the study area and several west Spitsbergen fjords are fed by the same glacier source (the ice field Lomonosovfonna), the final deglaciation of Wijdefjorden-Austfjorden took place after 9300 cal. years BP, i.e. at least approx. 2000 years later than in the west. We assume that the retarded deglaciation in the north is mainly related to the fjord bathymetry, i.e. a more than 35 km wide and up to 60 m high area in the central parts of the study area (approx. 45 km beyond the present fjord head) that acted as pinning point for the grounded glacier. Multiple, relatively large and partly stacked moraine ridges and sediment wedges are suggested to reflected that the ice front retreated slowly across this shallow area and that repeated readvances interrupted this retreat. The absence of larger sediment wedges in the deeper parts between the shallow area and the fjord head may indicate that the final retreat occurred relatively rapid. References: Baeten, N.J., Forwick, M., Vogt, C. & Vorren, T.O., 2010. Late Weichselian and Holocene sedimentary environments and glacial activity in Billefjorden, Svalbard. In: Howe, J.A., Austin, W.E.N, Forwick, M. & Paetzel, M. (eds.): Fjord Systems and Archives. Geological Society, London, Special Publication, 344, 207-223. Forwick, M. & Vorren, T.O., 2009. Late Weichselian and Holocene sedimentary environments and ice rafting in Isfjorden, Spitsbergen. Palaeogeography, Palaeoclimatology, Palaeoecology 280, 258-274. Forwick, M. & Vorren, T.O., 2011. Stratigraphy and deglaciation of the Isfjorden area, Spitsbergen. Norwegian Journal of Geology 90, 163-179. Ottesen, D., Dowdeswell, J.A., Rise, L., 2005. Submarine landforms and the reconstruction of fast-flowing ice streams within a large Quaternary ice sheet: The 2500-km-long Norwegian-Svalbard margin (57°-80°N). Geological Society of America Bulletin 117, 1033-1050.