Pleistocene subglacial tunnel valleys in the central North Sea basin: 3‐D morphology and evolution
Abstract 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...
Published in: | Journal of Quaternary Science |
---|---|
Main Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Wiley
2006
|
Subjects: | |
Online Access: | http://dx.doi.org/10.1002/jqs.1015 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjqs.1015 https://onlinelibrary.wiley.com/doi/pdf/10.1002/jqs.1015 |
id |
crwiley:10.1002/jqs.1015 |
---|---|
record_format |
openpolar |
spelling |
crwiley:10.1002/jqs.1015 2024-09-09T19:45:18+00:00 Pleistocene subglacial tunnel valleys in the central North Sea basin: 3‐D morphology and evolution Lonergan, Lidia Maidment, Susannah C. R. Collier, Jenny S. 2006 http://dx.doi.org/10.1002/jqs.1015 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjqs.1015 https://onlinelibrary.wiley.com/doi/pdf/10.1002/jqs.1015 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Journal of Quaternary Science volume 21, issue 8, page 891-903 ISSN 0267-8179 1099-1417 journal-article 2006 crwiley https://doi.org/10.1002/jqs.1015 2024-07-25T04:22:02Z Abstract 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 ... Article in Journal/Newspaper Ice Sheet Wiley Online Library Journal of Quaternary Science 21 8 891 903 |
institution |
Open Polar |
collection |
Wiley Online Library |
op_collection_id |
crwiley |
language |
English |
description |
Abstract 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 ... |
format |
Article in Journal/Newspaper |
author |
Lonergan, Lidia Maidment, Susannah C. R. Collier, Jenny S. |
spellingShingle |
Lonergan, Lidia Maidment, Susannah C. R. Collier, Jenny S. Pleistocene subglacial tunnel valleys in the central North Sea basin: 3‐D morphology and evolution |
author_facet |
Lonergan, Lidia Maidment, Susannah C. R. Collier, Jenny S. |
author_sort |
Lonergan, Lidia |
title |
Pleistocene subglacial tunnel valleys in the central North Sea basin: 3‐D morphology and evolution |
title_short |
Pleistocene subglacial tunnel valleys in the central North Sea basin: 3‐D morphology and evolution |
title_full |
Pleistocene subglacial tunnel valleys in the central North Sea basin: 3‐D morphology and evolution |
title_fullStr |
Pleistocene subglacial tunnel valleys in the central North Sea basin: 3‐D morphology and evolution |
title_full_unstemmed |
Pleistocene subglacial tunnel valleys in the central North Sea basin: 3‐D morphology and evolution |
title_sort |
pleistocene subglacial tunnel valleys in the central north sea basin: 3‐d morphology and evolution |
publisher |
Wiley |
publishDate |
2006 |
url |
http://dx.doi.org/10.1002/jqs.1015 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjqs.1015 https://onlinelibrary.wiley.com/doi/pdf/10.1002/jqs.1015 |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
Journal of Quaternary Science volume 21, issue 8, page 891-903 ISSN 0267-8179 1099-1417 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/jqs.1015 |
container_title |
Journal of Quaternary Science |
container_volume |
21 |
container_issue |
8 |
container_start_page |
891 |
op_container_end_page |
903 |
_version_ |
1809914913427030016 |