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The mixed‐bed glacial landform imprint of the North Sea Lobe in the western North Sea

Roberts, David H.; Grimoldi, Elena; Callard, Louise; Evans, David J.A.; Clark, Chris D.; Stewart, Heather A.; Dove, Dayton; Saher, Margot; Ó Cofaigh, Colm; Chiverrell, Richard C.; Bateman, Mark D.; Moreton, Steven G.; Bradwell, Tom; Fabel, Derek; Medialdea, Alicia

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Authors

Elena Grimoldi

Louise Callard

Chris D. Clark

Heather A. Stewart

Dayton Dove

Margot Saher

Richard C. Chiverrell

Mark D. Bateman

Steven G. Moreton

Tom Bradwell

Derek Fabel

Alicia Medialdea



Abstract

During the last glacial cycle an intriguing feature of the British‐Irish Ice Sheet was the North Sea Lobe (NSL); fed from the Firth of Forth and which flowed south and parallel to the English east coast. The controls on the formation and behaviour of the NSL have long been debated, but in the southern North Sea recent work suggests the NSL formed a dynamic, oscillating terrestrial margin operating over a deforming bed. Further north, however, little is known of the behaviour of the NSL or under what conditions it operated. This paper analyses new acoustic, sedimentary and geomorphic data in order to evaluate the glacial landsystem imprint and deglacial history of the NSL offshore from NE England. Subglacial tills (AF2/3) form a discontinuous mosaic interspersed with bedrock outcrops across the seafloor, with the partial excavation and advection of subglacial sediment during both advance and retreat producing mega‐scale glacial lineations and grounding zone wedges. The resultant ‘mixed‐bed’ glacial landsystem is the product of a dynamic switch from a terrestrial piedmont‐lobe margin with a net surplus of sediment to a partially erosive, quasi‐stable, marine‐terminating, ice stream lobe as the NSL withdrew northwards. Glaciomarine sediments (AF4) drape the underlying subglacial mixed‐bed imprint and point to a switch to tidewater conditions between 19.9 and 16.5ka cal BP as the North Sea became inundated. The dominant controls on NSL recession during this period were changing ice flux through the Firth of Forth ice stream onset zone and water depths at the grounding line; the development of the mixed‐bed landsystem being a response to grounding line instability.

Citation

Roberts, D. H., Grimoldi, E., Callard, L., Evans, D. J., Clark, C. D., Stewart, H. A., …Medialdea, A. (2019). The mixed‐bed glacial landform imprint of the North Sea Lobe in the western North Sea. Earth Surface Processes and Landforms, 44(6), 1233-1258. https://doi.org/10.1002/esp.4569

Journal Article Type Article
Acceptance Date Dec 6, 2018
Online Publication Date Jan 28, 2019
Publication Date May 31, 2019
Deposit Date Jan 4, 2019
Publicly Available Date Jan 28, 2020
Journal Earth Surface Processes and Landforms
Print ISSN 0197-9337
Electronic ISSN 1096-9837
Publisher British Society for Geomorphology
Peer Reviewed Peer Reviewed
Volume 44
Issue 6
Pages 1233-1258
DOI https://doi.org/10.1002/esp.4569

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Copyright Statement
Roberts, David H., Grimoldi, Elena, Callard, Louise, Evans, David J.A., Clark, Chris D., Stewart, Heather A., Dove, Dayton, Saher, Margot, Ó Cofaigh, Colm, Chiverrell, Richard C., Bateman, Mark D., Moreton, Steven G., Bradwell, Tom, Fabel, Derek & Medialdea, Alicia (2019). The mixed‐bed glacial landform imprint of the North Sea Lobe in the western North Sea. Earth Surface Processes and Landforms 44(6): 1233-1258. DOI. To view the published open abstract, go to https://doi.org/ and enter the DOI.





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