scholarly journals Structural analysis of the Rubjerg Knude Glaciotectonic Complex, Vendsyssel, northern Denmark

2005 ◽  
Vol 8 ◽  
pp. 1-192 ◽  
Author(s):  
Stig A. Schack Pedersen
Keyword(s):  
Structural Analysis ◽  
North Sea ◽  
Hanging Wall ◽  
Ice Sheet ◽  
Proximal Part ◽  
Thrust Fault ◽  
The North ◽  
Thrust Sheets ◽  
The North Sea ◽  
Fault Deformation

Pedersen, S.A.S. 2005: Structural analysis of the Rubjerg Knude Glaciotectonic Complex, Vendsyssel, northern Denmark. Geological Survey of Denmark and Greenland Bulletin 8, 192 pp. The Rubjerg Knude Glaciotectonic Complex is a thin-skinned thrust-fault complex that was formed during the advance of the Scandinavian Ice Sheet (30 000 – 26 000 B.P.); it is well exposed in a 6 km long coastal profile bordering the North Sea in northern Denmark. The glaciotectonic thrust-fault deformation revealed by this cliff section has been subjected to detailed structural analysis based on photogrammetric measurement and construction of a balanced cross-section. Thirteen sections are differentiated, characterising the distal to proximal structural development of the complex. The deformation affected three stratigraphic units: the Middle Weichselian arctic marine Stortorn Formation, the mainly glaciolacustrine Lønstrup Klint Formation and the dominantly fluvial Rubjerg Knude Formation; these three formations are formally defined herein, together with the Skærumhede Group which includes the Stortorn and Lønstrup Klint Formations. The Rubjerg Knude Formation was deposited on a regional unconformity that caps the Lønstrup Klint Formation and separates pre-tectonic deposits below from syntectonic deposits above. In the distal part of the complex, the thrust-fault architecture is characterised by thin flatlying thrust sheets displaced over the footwall flat of the foreland for a distance of more than 500 m. Towards the proximal part of the complex, the dip of the thrust faults increases, and over long stretches they are over-steepened to an upright position. The lowest décollement zone is about 40 m below sea level in the proximal part of the system, and shows a systematic step-wise change to higher levels in a distal (southwards) direction. The structural elements are ramps and flats related to hanging-wall and footwall positions. Above upper ramp-hinges, hanging-wall anticlines developed; footwall synclines are typically related to growth-fault sedimentation in syntectonic piggyback basins, represented by the Rubjerg Knude Formation. Blocks and slump-sheets constituting parts of the Lønstrup Klint Formation were derived from the tips of up-thrusted thrust sheets and slumped into the basins. Mud diapirs are a prominent element in the thrust-fault complex, resulting from mud mobilisation mainly at hanging-wall flats and ramps. Shortening during thrust-fault deformation has been calculated as 50%. Only about 11% of the initial stratigraphic units subjected to thrust faulting has been lost due to erosion. The thrust-fault deformation was caused by gravity spreading of an advancing ice sheet. Overpressured mud-fluid played an important role in stress transmission. The average velocity of thrust-fault displacement is estimated at 2 m per year, which led to compression of a 12 km stretch of flat-lying sediments, c. 40 m in thickness, into a thrust-fault complex 6 km in length. The thrust-fault complex is truncated by a glaciotectonic unconformity, formed when the advancing ice sheet finally overrode the complex. When this ice sheet melted away, a hilland- hole pair was formed, and meltwater deposits derived from a new ice-advance (NE-Ice) filled the depression. The NE-Ice overran the complex during its advance to the main stationary line situated in the North Sea. When this ice in turn melted away (c. 19 000 – 15 000 B.P.), the glacial landscape was draped by arctic marine deposits of the Vendsyssel Formation (new formation defined herein).

scholarly journals Structural analysis of the Rubjerg Knude Glaciotectonic Complex, Vendsyssel, northern Denmark

2005 ◽  
Vol 8 ◽  
pp. 1-32 ◽  
Author(s):  
Stig A. Schack Pedersen
Keyword(s):  
Structural Analysis ◽  
North Sea ◽  
Hanging Wall ◽  
Ice Sheet ◽  
Proximal Part ◽  
Thrust Fault ◽  
The North ◽  
Thrust Sheets ◽  
The North Sea ◽  
Fault Deformation

The Rubjerg Knude Glaciotectonic Complex is a thin-skinned thrust-fault complex that was formed during the advance of the Scandinavian Ice Sheet (30 000 – 26 000 B.P.); it is well exposed in a 6 km long coastal profile bordering the North Sea in northern Denmark. The glaciotectonic thrust-fault deformation revealed by this cliff section has been subjected to detailed structural analysis based on photogrammetric measurement and construction of a balanced cross-section. Thirteen sections are differentiated, characterising the distal to proximal structural development of the complex. The deformation affected three stratigraphic units: the Middle Weichselian arctic marine Stortorn Formation, the mainly glaciolacustrine Lønstrup Klint Formation and the dominantly fluvial Rubjerg Knude Formation; these three formations are formally defined herein, together with the Skærumhede Group which includes the Stortorn and Lønstrup Klint Formations. The Rubjerg Knude Formation was deposited on a regional unconformity that caps the Lønstrup Klint Formation and separates pre-tectonic deposits below from syntectonic deposits above. In the distal part of the complex, the thrust-fault architecture is characterised by thin flatlying thrust sheets displaced over the footwall flat of the foreland for a distance of more than 500 m. Towards the proximal part of the complex, the dip of the thrust faults increases, and over long stretches they are over-steepened to an upright position. The lowest décollement zone is about 40 m below sea level in the proximal part of the system, and shows a systematic step-wise change to higher levels in a distal (southwards) direction. The structural elements are ramps and flats related to hanging-wall and footwall positions. Above upper ramp-hinges, hanging-wall anticlines developed; footwall synclines are typically related to growth-fault sedimentation in syntectonic piggyback basins, represented by the Rubjerg Knude Formation. Blocks and slump-sheets constituting parts of the Lønstrup Klint Formation were derived from the tips of up-thrusted thrust sheets and slumped into the basins. Mud diapirs are a prominent element in the thrust-fault complex, resulting from mud mobilisation mainly at hanging-wall flats and ramps. Shortening during thrust-fault deformation has been calculated as 50%. Only about 11% of the initial stratigraphic units subjected to thrust faulting has been lost due to erosion. The thrust-fault deformation was caused by gravity spreading of an advancing ice sheet. Overpressured mud-fluid played an important role in stress transmission. The average velocity of thrust-fault displacement is estimated at 2 m per year, which led to compression of a 12 km stretch of flat-lying sediments, c. 40 m in thickness, into a thrust-fault complex 6 km in length. The thrust-fault complex is truncated by a glaciotectonic unconformity, formed when the advancing ice sheet finally overrode the complex. When this ice sheet melted away, a hilland-hole pair was formed, and meltwater deposits derived from a new ice-advance (NE-Ice) filled the depression. The NE-Ice overran the complex during its advance to the main stationary line situated in the North Sea. When this ice in turn melted away (c. 19 000 – 15 000 B.P.), the glacial landscape was draped by arctic marine deposits of the Vendsyssel Formation (new formation defined herein).

scholarly journals The North Sea Ice Sheet

Nature ◽  
1894 ◽  
Vol 50 (1282) ◽  
pp. 79-79
Author(s):  
HENRY H. HOWORTH
Keyword(s):  
Sea Ice ◽  
North Sea ◽  
Ice Sheet ◽  
The North ◽  
The North Sea

VII.—Glacier Lake Channels

1916 ◽  
Vol 3 (1) ◽  
pp. 26-29
Author(s):  
Percy Fry Kendall
Keyword(s):  
North Sea ◽  
Ice Sheet ◽  
Glacial Deposits ◽  
Marine Origin ◽  
The North ◽  
The North Sea

In 1902 I published a paper, the outcome of several years' observation, on certain phenomena associated with the glacial deposits of the Cleveland area, which I attributed to the former presence of a series of temporary lakes and lakelets upheld in the recesses of the hills by the margin of a great ice-sheet occupying the greater part of the North Sea. This interpretation met with so wide an acceptance, even by those geologists familiar with the district who had previously attributed the glacial deposits to a marine origin, that during the succeeding thirteen years I have steadfastly refrained from replying to criticism, hoping by this abstention to keep the issues unclouded by a controversy that might at any stage develop an acerbity not always lacking in earlier discussions.

VI.—On a Scandinavian Erratic from the Orkneys

1919 ◽  
Vol 6 (6) ◽  
pp. 273-274 ◽  
Author(s):  
W. I. Saxton ◽  
A. T. Hopwood
Keyword(s):  
North Sea ◽  
Ice Sheet ◽  
Glacial Period ◽  
General Behaviour ◽  
The North ◽  
Scandinavian Ice Sheet ◽  
Moray Firth ◽  
Westerly Direction ◽  
The North Sea

The general behaviour of the Scandinavian ice-sheet which spread over the North Sea at the climax of the Glacial period is fairly well known. Numerous erratics show that it reached the coast of Yorkshire and the eastern counties of England. Farther north no erratics have been found, but Dr. Jamieson and others have shown that it approached the coast of Aberdeen. Dr. Croll and Drs. Peach and Horne have shown that it forced the Scotch ice flowing eastward from the Moray Firth to turn in a northerly and north-westerly direction across the northern part of Caithness and over the Orkneys. They concluded that ice from the Christiania district must have passed a few miles to the north of the Orkneys. This is well shown in the chart attached to their paper and also in Professor James Geikie's map. The occurrence of a few Scandinavian erratics in the Orkneys would confirm these deductions. The only erratic recorded from Orkney which may be of Scandinavian origin is the Saville boulder described by Professor Heddle, Drs. Peach and Horne, and Dr. J. S. Flett.

Deglaciation dynamics of the Fennoscandian Ice Sheet in the Kattegat, the gateway between the North Sea and the Baltic Sea Basin

Boreas ◽  
2020 ◽  
Author(s):  
Outi Hyttinen ◽  
Nadina Quintana Krupinski ◽  
Ole Bennike ◽  
Lukas Wacker ◽  
Helena L. Filipsson ◽  
...  
Keyword(s):  
Baltic Sea ◽  
North Sea ◽  
Ice Sheet ◽  
The Baltic Sea ◽  
The North ◽  
The North Sea ◽  
The Baltic ◽  
Baltic Sea Basin

Abrupt last glacial loess-dust deposition over Southeast England coupled with dynamics of the British-Irish Ice Sheet

2021 ◽  
Author(s):  
Thomas Stevens ◽  
Daniele Sechi ◽  
Balázs Bradák ◽  
Ragna Orbe ◽  
Yunus Baykal ◽  
...  
Keyword(s):  
North Sea ◽  
Accumulation Rate ◽  
Dust Emission ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Last Glacial ◽  
The North ◽  
The North Sea ◽  
Dust Dynamics ◽  
Dust Accumulation

<p>Loess deposits are globally important dust archives but are often limited by imprecise chronological control. In particular, loess records adjacent to former ice sheets seldom have detailed, independent age models yet have the potential to elucidate the causes of past high latitude (>50° N in Northern Hemisphere) coarse dust emission close to former ice sheets, a relatively poorly known aspect of past dust dynamics. Loess deposits in southern Britain were formed in close proximity to western parts of the last glacial Eurasian ice sheets. However, currently their age and accumulation rate remain poorly known, limiting interpretation of the controls on last glacial coarse dust emission and deposition in the region.</p><p>Here we apply high sampling resolution quartz optically stimulated luminescence (OSL) to constrain the timing of dust accumulation and loess formation at the Pegwell Bay site in east Kent, SE England. The OSL ages and Bayesian (Bacon) age modelling results are the most detailed to date for western European loess, and show that loess began to accumulate around c. 25 ka, coinciding with Heinrich event 2 and the coupling of Fennoscandian and British-Irish ice sheets. There were two phases of greatly enhanced dust accumulation at the site, at 25-23.5 ka and 20-19 ka, separated by a lower accumulation rate period. Loess accumulation appears to have stopped or been dramatically reduced after 19-18 ka. We propose that the dynamics of the British-Irish and Fennoscandian Ice Sheets, associated glacial lake drainage, and linked reorganisations of atmospheric circulation, act to control loess accumulation at the site. In particular, we argue that both periods of enhanced dust accumulation were caused by advance-retreat phases of the North Sea ice lobe, and associated drainage of Dogger Lake. These events would have led to abrupt input of sediment-rich ice dammed lake and melt water from northern and eastern England and the North Sea into the exposed southern North Sea basin. This would have dramatically increased sediment availability for transport and deposition as loess in SE England. Easterly and north-easterly winds that could have transported this dust to SE England would have been enhanced by presence of an ice sheet anticyclone, enlarged during Fennoscandian and British-Irish ice sheet coalescence, as well as katabatic winds and easterly flow occurring on the northern side of Atlantic cyclones forced south of southern Britain by the extended western British-Irish ice sheet. As such, last glacial dust dynamics and loess accumulation in Britain is highly influenced by the interaction of the British-Irish and Fennoscandian ice sheets, Atlantic storm tracks, and the topography and drainage of the exposed North Sea basin.</p>

Detrital zircon U-Pb ages reveal ice sheet and North Sea drainage driven dust source variability recorded in late Quaternary loess deposits at Pegwell Bay, SE England

2021 ◽  
Author(s):  
Yunus Baykal ◽  
Thomas Stevens ◽  
Daniele Sechi ◽  
Giulia Cossu ◽  
Stefano Andreucci ◽  
...  
Keyword(s):  
North Sea ◽  
Detrital Zircon ◽  
Ice Sheet ◽  
Dust Deposition ◽  
Dust Source ◽  
The North ◽  
The North Sea ◽  
Single Grain ◽  
Loess Deposits ◽  
Two Phases

<p>Loess deposits are the most widespread terrestrial archive of past climate and environmental change. While several tens of metres thick loess-palaeosol sequences in central and eastern Europe record multiple glacial-interglacial cycles, substantially thinner deposits along the English Channel in north-western Europe may provide valuable “snapshots” of abrupt climatic and environmental changes in areas proximal to the North Atlantic. Recently, high-resolution luminescence dating of loess deposits at Pegwell Bay, SE England has enabled constraint of the timing of dust fall over south-east England to 25-19 ka when the British-Irish and Fennoscandian Ice sheets had coalesced and the associated strengthened high pressure system favoured dust entrainment from the exposed southern North Sea basin. Two phases of greatly enhanced dust deposition at the site are centred around 25-23.5 ka and 20-19 ka, contemporaneous with changes in North Sea ice sheet extent and ice dammed lake drainage. Such changes may have triggered abrupt flood events that would have greatly enhanced sediment supply potentially overriding the input from other sediment sources, e.g. major rivers like the Rhine. However, while the temporal link between ice sheet and dust dynamics is striking, this possibility remains untested due to lack of sufficiently source diagnostic provenance analyses of loess along the North Sea and Channel coasts. The use of single grain detrital zircon U-Pb age assemblages can discriminate different sources to loess in suitable settings. Given the geochronological heterogeneity of terranes that account for sediment input into the North Sea basin during the late last glacial ranging from Baltica in the east, Cadomia-Armorica in the south and Laurentia-Ganderia-Meguma-Avalonia in the north and west, detrital zircon ages have great promise to link changes in North Sea drainage with dust source activity. As such, high n detrital zircon age assemblages have here been analysed from two samples of loess deposited at Pegwell Bay during the two phases of enhanced dust deposition. Preliminary results indicate that glacifluvial sediments derived from both Scandinavia and Britain combined with input from major rivers draining central and western continental Europe act as dust source during the first phase while glacifluvial sediments from Britain dominate during the second phase linked to the final abrupt decay of the North Sea ice lobe. These findings based on single grain detrital zircon data alone highlight the method’s potential to detect abrupt dust source variability in a favourable scenario of heterogenous source terranes. They also emphasise the importance of abrupt changes in ice sheets and their drainage in controlling wider-scale, rapid and substantial changes in atmospheric dust emission in higher latitudes, and by extension possible subsequent climatic and environmental effects.</p>

scholarly journals Glacial Lake Pickering: stratigraphy and chronology of a proglacial lake dammed by the North Sea Lobe of the British-Irish Ice Sheet

2016 ◽  
Vol 32 (2) ◽  
pp. 295-310 ◽  
Author(s):  
David J. A. Evans ◽  
Mark D. Bateman ◽  
David H. Roberts ◽  
Alicia Medialdea ◽  
Laura Hayes ◽  
...  
Keyword(s):  
North Sea ◽  
Ice Sheet ◽  
Glacial Lake ◽  
The North ◽  
The North Sea ◽  
Proglacial Lake
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