Palaeomagnetic evidence for early Pleistocene in the central and northern North Sea

Stoker, Martyn S.; Skinner, A. C.; Fyfe, J. A.; Long, David A.

doi:10.1038/304332a0

Cited by 56 publications

(32 citation statements)

References 11 publications

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“…We note, however, that based on the presence of small amounts of IRD in sediments on the Vøring Plateau as old as 12.6 Ma, Fronval and Jansen (1996) suggested that glaciers and small ice caps large enough to calve into the sea have existed on land areas boarding the Nordic Seas during cold phases since middle Miocene times. More detailed stratigraphic information of the glacial deposits on the shelf are available both for the northern North Sea area (Stoker et al, 1983;Stoker and Bent, 1985;Sejrup et al, 1987Sejrup et al, , 1991Sejrup et al, , 1994Eidvin and Rundberg, 2001) and from the Mid-Norwegian shelf Eidvin et al, 1998;Dahlgren et al, 2002;Hjelstuen et al, 2004).…”

Section: Norwegian Marginmentioning

confidence: 97%

Pleistocene glacial history of the NW European continental margin

Sejrup

Hjelstuen

Dahlgren

et al. 2005

Marine and Petroleum Geology

245

203

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Section: Norwegian Marginmentioning

confidence: 97%

Pleistocene glacial history of the NW European continental margin

Sejrup

Hjelstuen

Dahlgren

et al. 2005

Marine and Petroleum Geology

245

203

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“…Good chronostratigraphic age-constraints on the Pleistocene stratigraphy of the offshore UK North Sea are largely lacking. The Brunhes-Matuyama palaeomagnetic reversal event (730 ka) was identified by Stoker et al (1983) in several BGS boreholes in the central North Sea within the preglacial deltaic succession (known as the Aberdeen Ground Formation in this area). The oldest tunnel valleys incise into this formation, and hence they can be constrained only as being younger than early Pleistocene in age.…”

Section: Study Area Stratigraphymentioning

confidence: 99%

“…This unit is the Aberdeen Ground Formation of Early-Middle Pleistocene age, which exhibits a similar seismic response in all of the central North Sea area (Stoker et al, 1985;Cameron et al, 1987). The Brunhes-Matuyama magnetic event at 730 ka was identified by Stoker et al (1983) within the Aberdeen Ground Formation in boreholes 75/33 and 81/26. Towards the top of the Aberdeen Ground Formation there is sedimentological and microfossil evidence for deterioration in climatic conditions in the central and northern North Sea (Stoker et al, 1985;Long et al, 1988), and thus the erosional unconformity, that defines the top of the Aberdeen Ground Formation and marks the base of the tunnel valley package, has been inferred by all previous workers to be of glacial origin.…”

Section: Age Constraintsmentioning

confidence: 99%

Pleistocene subglacial tunnel valleys in the central North Sea basin: 3‐D morphology and evolution

Lonergan

Maidment

Collier

2006

J Quaternary Science

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Four phases of cross-cutting tunnel valleys imaged on 3-D seismic datasets are mapped within the Middle-Late Pleistocene succession of the central North Sea basin (Witch Ground area).In plan the tunnel valleys form complex anastomosing networks, with tributary valleys joining main valleys at high angles. The valleys have widths ranging from 250 to 2300 m, and base to shoulder relief varying between 30 and 155 m, with irregular long-axis profiles characteristic of erosion by water driven by glaciostatic pressures. The youngest phase of tunnel valleys are smaller and have a thinner infill than the older generations. The fill of the larger valleys comprises three seismic facies, the lowermost of which has high amplitudes and is discontinuous. The middle facies consists of wedge-shaped packages of low-angle dipping reflectors and is overlain by a facies characterised by sub-horizontal reflectors, which onlap the valley margins. The seismic character, and comparison with lithologies identified in other northwest European Pleistocene tunnel valleys both onshore and offshore, suggests that the lower two seismic facies are most likely sand and gravel-dominated, while the uppermost facies consists of glaciolacustrine and marine muds. The 3-D morphology of the valley margins combined with the geometry of the infill packages suggest that episodic discharge of subglacial meltwater was responsible for incising the valleys and depositing at least some of the infill. Proglacial glaciofluvial deposits are inferred to account for some of the fill overlying the subglacial deposits. Glaciolacustrine and marine muds filled remaining valley topography as the ice sheet retreated. The preserved valley margins are shown to be time-transgressive erosion surfaces that record changes in geometry of the tunnel valley system as it evolved through time, implying that valleys associated with each ice-sheet advance/retreat cycle were dynamic and probably long-lived. Within the constraints of the existing stratigraphy the oldest tunnel valleys in the Witch Ground area of the central North Sea are most likely to be Marine Isotope Stage (MIS) 12 (Elsterian, ca. 470 ka) in age and the youngest pre-MIS 5e (last interglacial, ca. 120 ka). If each tunnel valley phase was formed during the retreat of a major ice sheet then four glaciations with ice coverage of the central North Sea are recorded in the pre-Weichselian, Middle-Late Pleistocene stratigraphy.

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“…Ice sheets reached the bed of the North Sea on numerous occasions in the Middle Pleistocene (Holmes, 1997) and periods of full ice cover can be inferred for the Cairngorms. The earliest Scottish ice sheet recognised from sediments in the northern North Sea is at 1.2 Ma (Stoker et al, 1983), but small glaciers probably developed in the mountains during stadial periods from the start of the Pleistocene at 2.6 Ma (Gordon, 1993). An ice cover model based on 18 O proxies and constrained by burial histories derived from two-nuclide cosmogenic isotope results indicates ice cover >7 m thick existed on the Cairngorms Plateau for at least half of the last 800 ka and almost all of MIS 4-2 .…”

Section: Cairngorm Torsmentioning

confidence: 99%

Glacial modification of granite tors in the Cairngorms, Scotland

Hall

Phillips

2006

J Quaternary Science

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A range of evidence indicates that many granite tors in the Cairngorms have been modified by the flow of glacier ice during the Pleistocene. Comparisons with SW England and the use of a space-time transformation across 38 tor groups in the Cairngorms allow a model to be developed for progressive glacial modification. Tors with deeply etched surfaces and no, or limited, block removal imply an absence of significant glacial modification. The removal of superstructure and blocks, locally forming boulder trains, and the progressive reduction of tors to stumps and basal slabs represent the more advanced stages of modification. Recognition of some slabs as tor stumps from which glacial erosion has removed all superstructure allows the original distribution of tors to be reconstructed for large areas of the Cairngorms. Unmodified tors require covers of non-erosive, cold-based ice during all of the cold stages of the Middle and Late Pleistocene. Deformation beneath cold-based glacier ice is capable of the removal of blocks but advanced glacial modification requires former wetbased glacier ice. The depth of glacial erosion at former tor sites remains limited largely to the partial or total elimination of the upstanding tor form. Cosmogenic nuclide exposure ages together with data from weathering pit depths , from the surfaces of tors and large erratic blocks require that the glacial entrainment of blocks from tors occurred in Marine Isotope Stages (MIS) 4-2, 6 and, probably, at least one earlier phase. The occurrence of glacially modified tors on or close to, the main summits of the Cairngorms requires full ice cover over the mountains during these Stages. Evidence from the Cairngorms indicates that tor morphology can be regarded as an important indicator of former ice cover in many formerly glaciated areas, particularly where other evidence of ice cover is sparse. Recognition of the glacial modification of tors is important for debates about the former existence of nunataks and refugia.

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Palaeomagnetic evidence for early Pleistocene in the central and northern North Sea

Cited by 56 publications

References 11 publications

Pleistocene glacial history of the NW European continental margin

Pleistocene glacial history of the NW European continental margin

Pleistocene subglacial tunnel valleys in the central North Sea basin: 3‐D morphology and evolution

Glacial modification of granite tors in the Cairngorms, Scotland

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