Quaternary of Norden

The Nordic countries have experienced multiple glaciations and intervening interglacials during the last ca. 2.5-3 million years. Although evidence from Greenland and Iceland shows that ice sheets started to expand some time before 3 Ma, little is known about the glaciations and intervening interglacials older than the last Glacial Maximum due to repeated phases of glacial erosion and reworking. The extensive Saalian glaciation （c. 140 ka BP） contributed to high sea levels in Greenland and in the Baltic area during the early part of the last interglacial （Eemian）. Temperatures were about 5 ℃ higher during the Eemian than they are today and the Greenland ice sheet was reduced to about half of its present size, causing globally higher sea levels than we have today. Ice extent in Fennoscandia was restricted during early Weichselian stadials, but middle Weichselian ice advances in Scandinavia reached as far as Denmark. During the Last Glacial Maximum, large ice sheets were present in all Nordic countries and coalesced with neighboring ice sheets. Deglaciation commenced around 17-15 ka BP in most areas and was promoted by rapidly rising global sea level and glacial isostasy. The Younger Dryas cold event（c. 12.6-11.5 ka BP） is seen as a short-term re-advance, still-stand or fluctuation of land-based ice sheet margins. Around 7-9 ka BP ice sheets had disappeared or had attained their present size. While uplift is still going on in some regions, others are subject to submergence. The different stages of development of the Baltic Sea are an example of how the intricare interplay between glacial eustasy and isostasy influences sedimentation, basin size and drainage patterns.     

Late Weichselian and Holocene sediment flux and sedimentation rates in Andfjord and Vågsfjord,North Norway

Late Weichselian and Holocene sediment flux and sedimentation rates in a continental‐shelf trough, Andfjord, and its inshore continuation, Vågsfjord, North Norway, have been analysed. The study is based on sediment cores and high‐resolution acoustic data. Andfjord was deglaciated between 14.6 and 13 ¹⁴C kyr BP (17.5 and 15.6 calibrated (cal.) kyr BP), the Vågsfjord basin before 12.5 ¹⁴C kyr BP (14.7 cal. kyr BP), and the heads of the inner tributary fjords about 9.7 ¹⁴C kyr BP (11.2 cal. kyr BP). In Andfjord, five seismostratigraphical units are correlated to a radiocarbon dated lithostratigraphy. Three seismostratigraphical units are recognised in Vågsfjord. A total volume of 23 km³ post‐glacial glacimarine and marine sediments was mapped in the study area, of which 80% are of Late Weichselian origin. Sedimentation rates in outer Andfjord indicate reduced sediment accumulation with increasing distance from the ice margin. The Late Weichselian sediment flux and sedimentation rates are significantly higher in Vågsfjord than Andfjord. Basin morphology, the position of the ice front and the timing of deglaciation are assumed to be the reasons for this. Late Weichselian sedimentation rates in Andfjord and Vågsfjord are comparable to modern subpolar glacimarine environments of Greenland, Baffin Island and Spitsbergen. Downwasting of the Fennoscandian Ice Sheet, and winnowing of the banks owing to the full introduction of the Norwegian Current, caused very high sedimentation rates in parts of the Andfjord trough at the Late Weichselian–Holocene boundary. Holocene sediment flux and sedimentation rates in Andfjord are about half the amount found in Vågsfjord, and about one‐tenth the amount of Late Weichselian values. A strong bottom current system, established at the Late Weichselian–Holocene boundary, caused erosion of the Late Weichselian sediments and an asymmetric Holocene sediment distribution. Copyright © 2002 John Wiley & Sons, Ltd.     

Integrated acoustic and coring investigation of glacigenic deposits in Spitsbergen fjords

In many areas of Svalbard, the Neoglacial terminal deposits represent the Holocene glacial maximum. The glaciers began the retreat from their Neoglacial maximum positions around 1900 AD. Based on high resolution acoustic data and sediment cores, sedimentation patterns in four tidewater glacier-influenced inlets of the fjord Isfjorden (Tempelfjorden, Billefjorden, Yoldiabukta and Borebukta), Spitsbergen, were investigated. A model for sedimentation of tidewater glaciers in these High Arctic environments is proposed. Glacigenic deposits occur in proximal and distal basins. The proximal basins comprise morainal ridges and hummocky moraines, bounded by terminal moraines marking the maximum Neoglacial ice extent. The distal basins are characterized by debris lobes and draping stratified glacimarine sediments beyond, and to some extent beneath and above, the lobes. The debris lobe in Tempelfjorden is composed of massive clayey silt with scattered clasts. Distal glacimarine sediments comprise stratified clayey silt with low ice-rafted debris (IRD) content. The average sedimentation rate for the glacimarine sediments in Tempelfjorden is 17 mm/yr for the last ca. 130 years. It is suggested that the stratified sediments in Tempelfjorden are glacimarine varves. The high sedimentation rate and low IRD content are explained by input from rivers, in addition to sedimentation from suspension of glacial meltwater. The debris lobes in Borebukta are composed of massive clayey silt with high clast content. Distal glacimarine sediments in Yoldiabukta comprise clayey silt with high IRD content. The average sedimentation rate for these sediments is 0.6 mm/yr for the last 2300 years.     

A submarine landslide complex affecting the Jan Mayen Ridge, Norwegian–Greenland Sea: slide-scar morphology and processes of sediment evacuation

Swath-bathymetry data and 2D multichannel seismics reveal for the first time an up to ~60 km wide amphitheater-shaped slide scar on the eastern flank of the Jan Mayen Ridge, a micro-continent in the Norwegian–Greenland Sea. The scar opens southeastward where it continues as a narrower, topographically controlled translational area. It includes secondary scars, as well as channels and escarpments. Based on the identification of secondary scars, the slide is classified as a slide complex and the total volume of missing sediments was estimated at ~60 km³. From the overall shape of the scar, the upslope widening from a bottleneck- or channel-like bypass-area, the failure is inferred to have had a retrogressive development. The absence of ridges, slabs and sediment blocks indicates that the failed sediments have been evacuated entirely. The smaller channels were formed from single or repetitive smaller flows post-dating the large failure events.     

Vegetation history of the European Quaternary

Lang, G. 1994: Quartäre Vrgetationsgeschichte Europas. Methoden und Ergebnisse . Gustav Fischer Verlag, Stuttgart/New York. 462 pp. (177 Figures, 54 Tables, 109 pp. addenda, index lists and references).     

Late Quaternary sediments and stratigraphy on the continental shelf off Troms and west Finnmark, northern Norway

Lithologic, paleontologic, and chronostratigraphic investigation of 13 gravity cores indicates the following environmental evolution: a high- (mid-) arctic period with a slight influx of ice-rafted debris occurred during the early middle Weichselian followed by a mid- (high-) arctic environment with a high influx of iceberg-rafted debris during the remainder of the middle Weichselian. The continental ice sheet probably did not extend beyond the inner shelf during middle Weichselian and a minimum relative sea level was ca. −120 m. A low-arctic environment occurred during (parts of) the late Weichselian with an initial winnowing of the sediments. The Norwegian Current entered the area during this substage. A high- (mid-) boreal environment occurred during the Holocene with high winnowing activity in the early Holocene. Winnowing is still very active on the shallower banks in contrast to the deeper banks where it has ceased. Relatively high percentages of carbonate in the form of biogenic skeletal remains occur in the Holocene sediments.     

Submerged terraces in the southwestern Barents Sea: origin and implications for the late Cenozoic geological history

Based on high-resolution seismics, submerged terraces have been identified and mapped. They constitute two semi-continuous terrace zones that can be followed for up to about 350 km along the bank flanks, at more or less uniform depths of ca. 150 m and ca. 220 m, respectively. The features are interpreted as wave-cut platforms, and thus indicate a submergence of as much as 220 m after they formed. Several arguments suggest that they were probably not formed during glaciation maxima, but rather during interglacials or parts of glacials with restricted glaciation. Consequently, only a smaller part of their submergence may be due to glacial eustasy. A signigicant tectonic related subsidence is inferred. Relatively young ages are indicated since they are so lightly eroded by the Plio-Pleistocene ice sheets. A maximum age in the order of 0.8 Ma and a minimum age of 0.2 Ma is tentatively suggested. One implication is that subsidence rates for this part of the Barents Sea margin are in the range 0.2–0.9 m/kyr.     

Palaeoenvironment in northern Norway between 22.2 and 14.5 cal. ka BP

The stratigraphy of lake Endletvatn on northern Andøya, northern Norway, has been revisited to improve the understanding of the palaeoenvironment in the region during the Last Glacial Maximum (LGM). Four high‐quality cores were analysed with respect to various lithological parameters and macrofossil content, supplemented by 47 AMS radiocarbon dates. The sediments indicate a low‐energy environment with a mean sedimentation rate of 0.5 mm a^?1. We infer perennially frozen ground in the surroundings during the LGM. Climate proxies indicate a high arctic climate (i.e. July mean temperatures between 0 and 3°C) throughout most of the LGM. The warmest periods are marked by a rise in seed, moss and animal fossils, and often also by higher organic production in the lake. These periods took place from 21.4 to 20.1, from 18.8 to 18.1, around 17 and from 16.4 cal. ka BP onwards. The shifts between the different climatic regimes occurred rapidly – probably during one or two decades. The present data do not support recently published conclusions stating that Picea, Pinus and Betula pubescens grew on Andøya during parts of the LGM. The highest relative sea level after the final deglaciation on northern Andøya is bracketed between 36 and 38 m a.s.l. It occurred between 21.0 and 20.3 cal. ka BP, peaking around 20.7 cal. ka BP. The final deglaciation of the northern tip of Andøya occurred 22.2 cal. ka BP. Then the western margin of the Andfjorden ice stream receded to the Kjølhaugen Moraine and shortly thereafter to the Endleten Moraine. Our research confirms that northern Andøya is a key location for understanding the natural environment in northwestern Europe during the LGM.     

The Middle and Late Pleistocence evolution and the Bear Island Trough Mouth Fan

The evolution of a submarine fan, the Bear Island Trough Mouth Fan, is outlined using high-resolution seismic data. Eight seismic units are identified. The identified units comprise sediments of Middle and Late Pleistocene age. They were probably deposited during eight glacial advances of the Barents Sea Ice Sheet to the shelf break. The units are dominated by a chaotic seismic signature on the upper fan and a mounded seismic facies further downslope. The mounded signature is inferred to reflect large submarine debris flow deposits, probably generated by oversteepening of the upper slope. Unlike many other passive margin fans, glacigenic sediments derived from an ice sheet at the shelf break were the primary sediment input. During interstadials and interglacials the sedimentation rate was reduced markedly. Three large sliding events also influenced the Middle and Late Pleistocene fan growth.     

The glacier-fed fan at the mouth of Storfjorden trough,western Barents Sea: a comparative study

The Middle and Late Pleistocene succession on the glacier-fed fan at the mouth of Storfjorden trough was studied using high-resolution seismic data. Seven glacial advances to the shelf break during Middle and Late Pleistocene resulted in episodic high sediment input to the fan with real sedimentation rates of up to 172 cm/1000 years, separated by sediment-starved interstadials and interglacials. On the upper fan the high sediment input resulted in frequent slides and slumps, generating debris flows which dominate the mid-fan strata. Compared with the larger neighbouring Bear Island trough mouth fan, the Storfjorden trough mouth fan has a steeper fan gradient, narrower, thinner and shorter debris flow deposits and lower frequency of large scale sliding. Glacier-fed submarine fans receive their main sediment input from a glacier margin at the shelf break, as opposed to river-fed fans where sediment input occurs through a channel-levee complex. As a result, the depocentre of a river-fed fan is found on the mid-fan and the upper slope is mainly an area of sediment bypass, whereas the glacier-fed fan has an elongated depocentre across the uppermost fan. The river-fed fans are dominated by deposition from turbidity currents, whereas glacier-fed fans are dominated by debris flow deposits.