Weichselian sediments at Foss‐Eikeland,Jæren (southwest Norway): sea‐level changes and glaciation history

The Jæren area in southwestern Norway has experienced great changes in sea‐levels and sedimentary environments during the Weichselian, and some of these changes are recorded at Foss‐Eikeland. Four diamictons interbedded with glaciomarine and glaciofluvial sediments are exposed in a large gravel pit situated above the post‐glacial marine limit. The interpretation of these sediments has implications for the history of both the inland ice and the Norwegian Channel Ice Stream. During a Middle Weichselian interstadial, a large glaciofluvial delta prograded into a shallow marine environment along the coast of Jæren. A minor glacial advance deposited a gravelly diamicton, and a glaciomarine diamicton was deposited during a following marine transgression. This subsequently was reworked by grounded ice, forming a well‐defined boulder pavement. The boulder pavement is followed by glaciomarine clay with a lower, laminated part and an upper part of sandy clay. The laminated clay probably was deposited under sea‐ice, whereas more open glaciomarine conditions prevailed during deposition of the upper part. The clay is intersected by clastic dykes protruding from the overlying, late Weichselian till. Preconsolidation values from the marine clay suggest an ice thickness of at least 500 m during the last glacial phase. The large variations in sea‐level probably are a combined effect of eustasy and glacio‐isostatic changes caused by an inland ice sheet and an ice stream in the Norwegian Channel. Copyright © 2002 John Wiley & Sons, Ltd.     

Turbiditic,clay‐rich event beds in fjord‐marine deposits caused by landslides in emerging clay deposits – palaeoenvironmental interpretation and role for submarine mass‐wasting

Distinct, clay‐rich beds are common in fjord‐marine deposits in Trondheimsfjorden near the outlet of the Nidelva River. Their characteristic light‐grey colour makes the beds easily distinguishable from the surrounding brownish, bioturbated, muddy fjord sediments. The clay‐rich beds commonly display a clear stratification in clay, silt and very fine sand. The beds are interpreted as originating primarily from large quick‐clay landslides upstream along the Nidelva River. Such events resulted in a sudden increase in the supply of fines to the fjord from disintegrating landslide debris and heavily loaded effluent plumes, possibly favouring hyperpycnal flow. Typical beds can be divided into a clay‐rich lower section, reflecting an initial surge with high concentrations of suspended mud, and a sandier upper section reflecting pulses of higher energy. This development can be explained, for example, by a lowering in the supply of mud, an increasing activity of deltaic sediment gravity flows due to a higher availability of sandy sediments in the landslide‐affected river, and by flooding and/or breaching of landslide dams. The typical, stratified beds are interpreted as the result of one quick‐clay landslide, whereas exceptionally thick, less organized, stratified beds are possibly the result of several large and/or complex landslides. Radiocarbon dating of mollusc shells has helped to establish a chronology for major terrestrial landslides in the area. The frequency of landslides increases towards the end of the Holocene. This is explained by a progressively deeper incision of rivers during glacioisostatic rebound, possibly combined with a change to a wetter climate. The marine core record displays deformation structures and hiati representing submarine mass‐wasting events, and supports the evidence that the clay‐rich beds are weak layers in the fjord‐marine stratigraphy. The inherent weakness of these layers may be explained by their composition, immature texture, loose fabric and contrasting permeabilities in the deposits. Slide‐prone layers similar to the clay‐rich beds described here may be found in other comparable fjord‐marginal settings and are considered to be of importance for geohazard assessments.     

Facies characteristics, morphology and depositional models of clay-slide deposits in terraced fjord valleys, Norway

Many bedrock-confined fjord valleys along the Norwegian coast contain thick accumulations of fine-grained sediments that were deposited during and after the last deglaciation. The deposits gradually emerged above sea level due to glacioisostatic uplift, and fjord marine sedimentation was gradually followed by shallow marine and fluvial processes. During emergence terraces and river-cut slopes were formed in the valleys. Subsequent leaching of salt ions from the pore water in the marine deposits by groundwater has led to the development of quick clay. The deposits are subject to river erosion and destructive landslides involving quick clay. Most slides are of prehistoric age. Others are known from modern observations as well as from historic records.Landforms such as distinct slide scars or the hummocky terrain of slide deposits may be strongly modified by secondary processes. In addition, deposits from the most liquid part of quick clay slides may have planar surfaces. Clay-slide deposits on a fluvial or deltaic terrace, therefore, are not always easily recognized from morphology, and only exposures may reveal their internal structures and allow them to be distinguished from overbank flood sediments. Detailed sedimentological work shows that slide deposits in such setting consist of distinct facies containing reworked marine sediments. We propose three facies successions of clay-slide deposits that form a continuum. The dominant components of these succession types are: slightly deformed blocks of laminated clay and silt (A), highly deformed clay and silt with gravel clasts (B) and massive to stratified clay and silt with scattered clasts (C). We suggest that in many cases a basal muddy diamicton is a characteristic, and possibly diagnostic feature. Processes and depositional models are interpreted from the different succession types. The results may be relevant for identifying clay-slide deposits elsewhere and may be useful during general mapping of fjord marine deposits and characterization of slide-prone areas as well as during identification of prehistoric slides.     

Fjord infill in a high-relief area: Rapid deposition influenced by deglaciation dynamics, glacio-isostatic rebound and gravitational activity

Lyså, A., Hjelstuen, B. O. & Larsen, E. 2009: Fjord infill in a high‐relief area: Rapid deposition influenced by deglaciation dynamics, glacio‐isostatic rebound and gravitational activity. Boreas, 10.1111/j.1502‐3885.2009.00117.x. ISSN 0300‐9483. Seismic profiles and gravity cores have been collected from the previously glaciated Nordfjord system on the west coast of Norway. The results give new information about the deglaciation history of the area and contribute to our understanding of fjord fill in high relief areas. During the last deglaciation, up to 360 m of sediments was deposited in the 135 km long fjord system. Shortly after the coastal area became ice‐free, ～12 300 ¹⁴C years BP, the first ice‐marginal deposits were formed, probably due to a minor glacier re‐advance. The greatest volume of sediments in the fjord was deposited during the Allerød ice recession period, the Younger Dryas re‐advance and the succeeding ice retreat period until the ice disappeared from the fjord in early Preboreal. During the Allerød, the fjord was ice‐free and glaciomarine stratified sediments were deposited. The ice margin is suggested to have been located just west of Lake Strynevatnet before the advance during the Younger Dryas. In the late phase of the Younger Dryas, and within the succeeding ～1000 years, the glacio‐isostatic rebound was rapid, and extensive re‐sedimentation took place. Slide activities continued into mid‐Holocene, albeit with less intensity and were followed by normal and calm marine conditions that prevailed until the present. One huge rock avalanche into the fjord took place between 2200 and 1800 ¹⁴C yr BP, probably triggering a tsunami and several slides in the fjord. Even though glacigenic sediments totally dominate in terms of sediment volume, the present study underlines the importance of re‐sedimentation and other gravitational processes in such fjord settings.     

Late‐glacial to Holocene environmental changes and climate variability: evidence from Voldafjorden,western Norway

Sedimentological, micropalaeontological (benthic foraminifers and dinoflagellate cysts), stable isotope data and AMS ¹⁴C datings on cores and surface samples, in addition to acoustic data, have been obtained from Voldafjorden, western Norway. Based on these data the late glacial and Holocene sedimentological processes and variability in circulation and fjord environments are outlined. Glacial marine sedimentation prevailed in the Voldafjorden between 11.0 kyr and 9.2 kyr BP (radiocarbon years). In the later part of the Allerød period, and for the rest of the Holocene, there was deposition of fine‐grained normal marine sediments in the fjord basin. Turbidite layers, recorded in core material and on acoustic profiles, dated to ca. 2.1, 6.9–7.6, ca. 9.6 and ca. 11.0 kyr BP, interrupted the marine sedimentation. The event dated to between 6.9 and 7.6 kyr BP probably corresponds to a tsunami resulting from large‐scale sliding on the continental margin off Norway (the Storegga Tsunami). During the later part of the Allerød period, Voldafjorden had a strongly stratified water column with cold bottom water and warm surface water, reaching interglacial temperatures during the summer seasons. During the Younger Dryas cold event there was a return to arctic sea‐surface summer temperatures, possibly with year‐round sea‐ice cover, the entire benthic fauna being composed of arctic species. The first strong Holocene warming, observed simultaneously in bottom and sea‐surface temperature proxies, occurred at ca. 10.1 kyr BP. Bottom water proxies indicate two cold periods, possibly with 2°C lowering of temperatures, at ca. 10.0 (PBO 1) and at 9.8 kyr BP (PBO 2). These events may both result from catastrophic outbursts of Baltic glacial lake water. The remainder of the Holocene experienced variability in basin water temperature, indicated by oxygen isotope measurements with an amplitude of ca. 2°C, with cooler periods at ca. 8.4–9.0, 5.6, 5.2, 4.6, 4.2, 3.5, 2.2, 1.2 and 0.4–0.8 kyr BP. Changes in the fjord hydrology through the past 11.3 kyr show a close correspondence, both in amplitude and timing of events, recorded in cores from the Norwegian Sea region and the North Atlantic. These data suggest a close relationship between fjord environments and variability in large‐scale oceanic circulation. Copyright © 2001 John Wiley & Sons, Ltd.     

Stratigraphy,sedimentology, age and palaeoenvironment of marine varved clay in the Middle Swedish end‐moraine zone

Johnson, M. D. & Ståhl, Y. 2009: Stratigraphy, sedimentology, age and palaeoenvironment of marine varved clay in the Middle Swedish end‐moraine zone. Boreas, 10.1111/j.1502‐3885.2009.00124.x. ISSN 0300‐9483 Deglaciation of the Middle Swedish end‐moraine zone and age of the sediment in and between the moraines have been discussed for about a hundred years. The goal of this project was to determine the stratigraphy and age of the sediment in and between the moraines. Inter‐moraine flats are underlain by clay, 10–25 m thick, overlying thin sand and gravel or till on bedrock. The clay is overlain by a few metres of sand and gravel. Much of the clay beneath the flats consists of rhythmites that grade from grey to red and are 2–74 cm thick. Our interpretation of these rhythmites as being varves is supported by grain size and mineralogical and elemental variations. Foraminifera and ostracods show that the clay was deposited in an arctic marine environment, while radiocarbon dating of the microfossils indicates that the clay was deposited 12 150 cal. ¹⁴C years ago, during the Younger Dryas chronozone (YD). Most of the optical stimulated luminescence dates on the clay are much older, containing quartz sand that was insufficiently bleached. The stratigraphy indicates that the moraines are composed of YD clay pushed into ridge forms during ice‐front oscillations. It is not possible to determine how far north the Scandinavian Ice Sheet retreated prior to the YD advance. We neither support nor reject the suggestion that the ice margin retreated to the northern edge of Mt. Billingen during the Allerød, causing the Baltic Ice Lake to drain.     

Recurrent interaction between the Norwegian Channel Ice Stream and terrestrial‐based ice across southwest Norway

The occurrence of till beds alternating with glaciomarine sediment spanning oxygen isotope stages 6 to 2, combined with morphological evidence, shows that the southwestern fringe of Norway was inundated by an ice stream flowing through the Norwegian Channel on at least four occasions, the last time being during the Late Weichselian maximum. All marine units are deglacial successions composed of muds with dropstones and diamictic intrabeds and a foraminiferal fauna characteristic of extreme glaciomarine environments. Land‐based ice, flowing at right angles to the flow direction of the ice stream, fed into the ice stream along an escarpment formed by erosion of the ice stream. Each time the ice stream wasted back, land‐based ice advanced into the area formerly occupied by the ice stream. During the last deglaciation of the ice stream (c. 15 ka BP), the advance of the land‐based ice occurred immediately upon ice stream retreat. As a result, the sea was prevented from inundating the upland areas, allowing most of the glacioisostatic readjustment to occur before the land‐based ice melted back at about 13 ka BP. This explains the low Late Weichselian sea levels in the area (10–20 m) compared with those of the Middle Weichselian and older sea‐level high stands (～200 m). Regional tectonic movements cannot explain the location of the observed marine successions. The highest sea level recorded (>200 m) is represented by glaciomarine sediments from the Sandnes interstadial (30–34 ka BP). Older interstadial marine sediments are found at somewhat lower levels, possibly as a result of subsequent glacial erosion in these deposits. Ice streams developed in the Norwegian Channel during three Weichselian time intervals. This seems to correspond to glacial episodes both to the south in Denmark and to the north on the coast of Norway, although correlations are somewhat hampered by insufficient dating control.     

Stratigraphic evaluation of a Holocene clay-slide in Northern Norway

An almost 6,000 years old slide in marine clay at Fossmoen, Northern Norway is studied to: characterize the scar, the slide deposits and the slide event; evaluate the role that stratigraphic variations played for failure; and view the slide event within long-term landscape development. A geological model for the area is based on drilling, outcrops and ground-penetrating radar with emphasis on the stratigraphic variations of fjord deposits. The slide’s age implies that the deposits were sensitive already shortly after emergence above sea level, and layers are still sensitive. River incision was probably responsible for the initial slide, whereas stratigraphy and groundwater movement controlled the location and shape of the scar. Laminated, inclined and discontinuous bedding are suggested as playing different roles for ground-water flow and pore pressures, adding to existing models on the development of soft and sensitive layers prone to sliding.     

Discussion and Reply: Shaping the Australian crust over the last 300 million years: Insights from fission track thermotectonic imaging and denudation studies of key terranes

Ellis Fjord is a small, fjord‐like marine embayment in the Vestfold Hills, eastern Antarctica. Modern sediment input is dominated by a biogenic diatom rain, although aeolian, fluvial, ice‐rafted, slumped and tidal sediments also make a minor contribution. In areas where bioturbation is significant relict glaciogenic sediments are reworked into the fine‐grained diatomaceous sediments to produce poorly sorted fine sands and silts. Where the bottom waters are anoxic, sediments remain unbioturbated and have a high biogenic silica component. Three depositional and non‐depositional facies can be recognised in the fjord: an area of non‐deposition around the shoreline; a relict morainal facies in areas of low sedimentation and high bioturbation; and a basinal facies in the deeper areas of the fjord.     

Stratigraphical signatures of glacier activity,marine processes and a possible tsunami in the Leirfjorden fjord‐valley system,north Norway

An integrated interpretation of on‐ and offshore stratigraphical records at Leirfjorden, north Norway, reveals new aspects of the area's palaeoenvironmental history. The study is based on marine sparker data and well‐exposed sections on land that were analysed for their sediment facies, mineralogy and fossil assemblages. Existing research and new radiocarbon dates provide a chronological framework for the interpretation. The late Younger Dryas Nordli substage type locality in the Leirfjorden catchment is revised and found to reflect local glacial activity, maybe a collapse of stagnant ice rather than glacier advance, while late Younger Dryas to Preboreal glacier re‐advances south of Leirfjorden and near Ranfjorden are here named the Bardal substage. The stratigraphical record includes pre‐Younger Dryas, valley‐crossing, glacial striae and old till with provenance of resistant bedrock typical of more elevated mountain areas. It differs from younger till units representing topographically controlled glacier movement. Part of the Leirfjorden fjord‐valley system is located between the main glacial and fluvial drainage paths affecting the sediment supply. As a result, highstand deposits are indistinct and fluvial sediments form only a minor part of the forced‐regressive systems tract. Instead, the valley fill overlying till and subtill sediments is dominated by the deglacial transgressive tract and a forced‐regressive systems tract with composite marine deposits and various marine erosion surfaces. A special event bed is interpreted as a possible tsunami deposit caused by seismicity and/or mass‐wasting in the fjord following glacier retreat. The study highlights the stratigraphical complexity of interconnected fjord and sound systems in a low accretion setting.     

Geophysical surveys of the sediments of Loch Ness,Scotland: implications for the deglaciation of the Moray Firth Ice Stream,British–Irish Ice Sheet

We present results from three geophysical campaigns using high‐resolution sub‐bottom profiling to image sediments deposited in Loch Ness, Scotland. Sonar profiles show distinct packages of sediment, providing insight into the loch's deglacial history. A recessional moraine complex in the north of the loch indicates initial punctuated retreat. Subsequent retreat was rapid before stabilisation at Foyers Rise formed a large stillstand moraine. Here, the calving margin produced significant volumes of laminated sediments in a proglacial fjord‐like environment. Subsequent to this, ice retreated rapidly to the southern end of the loch, where it again deposited a sequence of proglacial laminated sediments. Sediment sequences were then disturbed by the deposition of a thick gravel layer and a large turbidite deposit as a result of a jökulhlaup from the Spean/Roy ice‐dammed lake. These sediments are overlain by a Holocene sheet drape. Data indicate: (i) a former tributary of the Moray Firth Ice Stream migrated back into Loch Ness as a major outlet glacier with a calving margin in a fjord‐like setting; (ii) there was significant sediment supply to the terminus of this outlet glacier in Loch Ness; and (iii) that jökulhlaups are important for sediment supply into proglacial fjord/lake environments and may compose >20% of proglacial sedimentary sequences. Copyright © 2011 John Wiley & Sons, Ltd.     

The retreat of the Barents Sea Ice Sheet on the western Svalbard margin

The deglaciation of the continental shelf to the west of Spitsbergen and the main fjord, Isfjorden. is discussed based on sub-bottom seismic records and scdirncnt cores. The sea lloor on the shelf to the west of Isfjorden is underlain by less than 2 m of glaciomarine sediments over a firm diamicton interpreted as till. In central Isfjordcn up to 10 m of deglaciation sediments were recorded, whereas in cores from the innermost tributary, Billefjorden, less than a meter of ice proximal sediments was recognized between the till and the 'normal' Holocene marine sediments. We conclude that the Barents Sea Ice Sheet terminated along the shelf break during the Late Weichselian glacial maximum. Radiocarbon dates from thc glaciomarine sediments above the till indicate a stepwise deglaciation. Apparently the ice front rctrcatcd from the outermost shelf around 14. 8 ka A dramatic increase in the flux of line-grained glaciomarine sediments around 13 ka is assumed to reflect increased melting and/or current activity due to a climatic warming. This second stage of deglaciation was intcrruptcd by a glacial readvance culminating on the mid-shelf area shortly after 12.4 ka. The glacial readvance, which is correlated with a simultaneous readvance of the Fennoscundian ice sheet along the western coast of Norway, is attributed to the so-called 'Older Dryas' cooling event in the North Atlantic region. Following this glacial readvance the outer part of Isljorden became rapidly deglaciated around 12.3 ka. During the Younger Dryas the inner fjord branches were occupied by large outlet glaciers and possibly the ice liont terminated far out in the main fjord. The remnants of the Harcnts Sea Ice Shcet melted quickly away as a response to the Holocene warming around 10 ka.     

Lateglacial landform associations at Jæren (SW Norway) and their glaci-dynamic implications

The Jæren lowland is located on the southwestern coast of Norway between a mountainous region in the east and the offshore Norwegian Channel in the west. During the Last Glacial Maximum, Jæren was in an intermediate position between an ice stream following the Norwegian Channel northwards, and westward flowing inland ice. The dynamic behaviour of the inland ice and the interaction with the ice stream are examined by means of geomorphological analysis of digital terrain models and sedimentological investigations. SW-trending drumlins were formed at Jæren below tributary ice from the inland, feeding into the Norwegian Channel Ice Stream. The presence of Rogen moraine in the central part of Jæren indicates a frozen substratum prior to their formation, and this suggests a transition to cold-based ice between the tributaries. The deglaciation of the Norwegian Channel at about 15 ka BP resulted in an unstable ice front for the inland ice sheet. The formation of Rogen moraine may be explained by a dynamic advance resulting in extensional flow and fracturing of the frozen substratum between the tributaries. The dynamic advance was followed by an early deglaciation of the coastal areas as evidenced by shallow marine sediments. Deformation of the shallow marine sand indicates a glacial readvance through the valleys formerly acting as tributaries to the ice stream.     

Holocene sedimentation in the Skagerrak interpreted from chirp sonar and core data

High‐resolution chirp sonar profiling in the northeastern Skagerrak shows acoustically stratified sediments draping a rough‐surfaced substratum. A 32 metre long sediment core retrieved from the survey area encompasses the entire Holocene and latest Pleistocene. The uppermost seismo‐acoustic units in the chirp profiles represent Holocene marine sediments. The lowermost unit is interpreted as ice‐proximal glacial‐marine sediments rapidly deposited during the last deglaciation. The end of ice‐proximal sedimentation is marked by a strong reflector, interpreted to have been formed during latest Pleistocene time as a consequence of rapid ice retreat and drastically lowered sedimentation rate. The subsequent distal glacial‐marine sediments were deposited with initially high sedimentation rates caused by an isostatic rebound‐associated sea‐level fall. Based on correlation between the core and the chirp sonar profiles using measured sediment physical properties and AMS ¹⁴C dating, we propose a revised position for the Pleistocene/Holocene boundary in the seismo‐acoustic stratigraphy of the investigated area. Copyright © 2005 John Wiley & Sons, Ltd.     

Dinoflagellate cysts in Upper Quaternary sediments from southwestern Norway and potential correlations with the oceanic record

Twenty-two samples from two locations at the Foss-Eigeland clay and gravel pit, Jæren, southwestern Norway were analysed for dinoflagellate cysts. Cyst recovery was generally poor and cyst assemblages indicate a cold temperate to arctic glacimarine environment. The percentage composition of a total of 19 cyst species identified allowed the recognition of five assemblage zones. These are thought to reflect fluctuating minor climatic changes during an interstadial period preceding the last glacial advance in the region. Cyst assemblages from these supposedly Middle Weichselian sediments at Foss-Eigeland are similar to those found in the northern North Sea and the Norwegian Sea in probably similarly aged sediments. This suggests a potential for using dinoflagellate cysts to correlate land-based Quaternary sequences with the deep sea record.     

Benthonic foraminifera as indicators of the paleoposition of the Subarctic Convergence in the Norwegian-Greenland Sea

A method is presented for correlating benthonic foraminiferal communities in Late Quaternary marine sediments on continental shelves and in coastal areas with the planktonic foraminiferal stratigraphy of the North Atlantic and Norwegian Sea deep-sea sediments.     

Litho- and chronostratigraphy of the Late Weichselian in Vendsyssel, northern Denmark, with special emphasis on tunnel-valley infill in relation to a receding ice margin

Lithostratigraphy and chronostratigraphy of samples from 18 deep boreholes in Vendsyssel have resulted in new insight into the Late Weichselian glaciation history of northern Denmark. Prior to the Late Weichselian Main advance c. 23–21 kyr BP, Vendsyssel was part of an ice‐dammed lake where the Ribjerg Formation was deposited c. 27–23 kyr BP. The timing of the Late Weichselian deglaciation is well constrained by the Main advance and the Lateglacial marine inundation c. 18 kyr BP, and thus spans only a few millennia. Rapid deposition of more than 200 m of sediments took place mainly in a highly dynamic proglacial and ice‐marginal environment during the overall ice recession. Mean retreat rates have been estimated as 45–50 m/yr in Vendsyssel with significantly higher retreat rates between periods of standstill and re‐advance. The deglaciation commenced in Vendsyssel c. 20 kyr BP, and the Troldbjerg Formation was deposited c. 20–19 kyr BP in a large ice‐dammed lake in front of the receding ice sheet, partly as glaciolacustrine sediments and partly as rapid and focused sedimentation in prominent ice‐contact fans, which make up the Jyske Ås and Hammer Bakker moraines. In the northern part of central Vendsyssel, at least four generations of north–south orientated tunnel valleys are identified, each generation related to a recessional ice margin. This initial deglaciation was interrupted by a major re‐advance from the east c. 19 kyr BP, which covered most of Vendsyssel. An ice‐dammed lake formed in front of the ice sheet as it retreated towards the east; the Morild Formation was deposited here c. 19–18 kyr BP. Related to this stage of deglaciation, eight ice‐marginal positions have been identified based on the distribution of large tunnel‐valley systems and pronounced recessional moraines. The Morild Formation consists of glaciolacustrine sediments, including the sediment infill of more than 190 m deep tunnel valleys, as well as the sediments in recessional moraines, which were formed as ice‐contact sedimentary ridges, possibly in combination with glaciotectonic deformation. The character of the tunnel‐valley infill sediments was determined by proximity to the ice margin. During episodes of rapid retreat of the ice margin, tunnel valleys were quickly abandoned and filled with fine‐grained sediments in a distal setting. During slow retreat of the ice margin, tunnel valleys were filled in an ice‐proximal environment, and the infill consists of alternating layers of fine‐ to coarse‐grained sediments. At c. 18 kyr BP, Vendsyssel was inundated by the sea, when the Norwegian Channel Ice Stream broke up, and a succession of marine sediments (Vendsyssel Formation) was deposited during a forced regression.     

Pattern and timing of the northwestern Barents Sea Ice Sheet deglaciation and indications of episodic Holocene deposition

The origin of two acoustic sediment units has been studied based on lithological facies, chronology and benthic stable isotope values as well as on foraminifera and clay mineral assemblages in six marine sediment cores from Kveithola, a small trough west of Spitsbergenbanken on the western Barents Sea margin. We have identified four time slices with characteristic sedimentary environments. Before c. 14.2 cal. ka, rhythmically laminated muds indicate extensive sea ice cover in the area. From c. 13.9 to 14.2 cal. ka, muds rich in ice‐rafted debris were deposited during the disintegration of grounded ice on Spitsbergenbanken. From c. 10.3 to 13.1 cal. ka, sediments with heterogeneous lithologies suggest a shifting influence of suspension settling and iceberg rafting, probably derived from a decaying Barents Sea Ice Sheet in the inner‐fjord and land areas to the north of Kveithola. Holocene deposition was episodic and characterized by the deposition of calcareous sands and shell debris, indicative of strong bottom currents. We speculate that a marked erosional boundary at c. 8.2 cal. ka may have been caused by the Storegga tsunami. Whilst deposition was sparse during the Holocene, Kveithola acted as a sediment trap during the preceding deglaciation. Investigation of the deglacial sediments provides unprecedented details on the dynamics and timing of glacial retreat from Spitsbergenbanken.     

The Late Quaternary sedimentary record in Scoresby Sund, East Greenland

Until recently, little was known about the Quaternary marine sedimentary record in East Greenland. Geophysical and geological investigations in Scoresby Sund were undertaken to characterize the nature and chronology of this record. Seismic records show that almost 70% of the outer fjord system is covered by about 10 m of unlithified sediments, making direct correlation with the Quaternary records on land and the adjacent continental margin difficult. These acoustically unstratified sediments are scoured by icebergs above 550 m water depth. Almost 90% of core material is massive diamicton of Holocene age, deposited mainly from iceberg rafting and turbid meltwater. Sedimentation rates are 0.1 -0.3 m 1000 yr-¹. Thicker accumulations of unlithified Quaternary sediments in Scoresby Sund occur as sediment ridges and in two other major depocentres. A low sediment ridge runs across the mouth of Scoresby Sund, and is interpreted as an end moraine of Late Weichselian Flakkerhuk stadial age. The very restricted sediment thickness suggests that grounded ice filled the fjord during the Flakkerhuk and an ice shelf was not present. High inputs of ice rafted debris to the continental margin at about 18 000 BP indicate this as a probable age for the moraine. During the Allerød Interstadial, ice probably retreated from the outer fjord system, since massive diamictons similar to those of Holocene age are present at the base of most cores. A major depocentre of acoustically stratified sediments at the head of Hall Bredning is interpreted to represent ice proximal deposits from a glacier margin extending across the fjord. It is adjacent to dated moraines on land and is inferred to be of Milne Land stadial age (about 10 000 BP). A similar age is interpreted for acoustically laminated sediments and a moraine at the entrance of Vikingebugt, on the south side of Scoresby Sund. Dated kame terraces in the inner fjord system indicate that ice retreated to its present position 6–7000 years ago.     

Quaternary denudation of southern Fennoscandia – evidence from the marine realm

Throughout the last 1.1 million years repeated glaciations have modified the southern Fennoscandian landscape and the neighbouring continental shelf into their present form. The glacigenic erosion products derived from the Fennoscandian landmasses were transported to the northern North Sea and the SE Nordic Seas continental margin. The prominent sub‐marine Norwegian Channel trough, along the south coast of Norway, was the main transport route for the erosion products between 1.1 and 0.0 Ma. Most of these erosion products were deposited in the North Sea Fan, which reaches a maximum thickness of 1500 m and has nearly 40 000 km³ of sediments. About 90% of the North Sea Fan sediments have been deposited during the last 500 000 years, in a time period when fast‐moving ice streams occupied the Norwegian Channel during each glacial stage. Back‐stripping the sediment volumes in the northern North Sea and SE Nordic Seas sink areas, including the North Sea Fan, to their assumed Fennoscandian source area gives an average vertical erosion of 164 m for the 1.1–0.0 Ma time period. The average 1.1–0.0 Ma erosion rate in the Fennoscandian source area is estimated to be 0.15 mm a^?1. We suggest, however, that large variations in erosion rates have existed through time and that the most intense Fennoscandian landscape denudation occurred during the time period of repeated shelf edge ice advances, namely from Marine Isotope Stage 12 (c. 0.5 Ma) onwards.