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The deforming bed characteristics of a stratified till assemblage in north East Anglia, UK: investigating controls on sediment rheology and strain signatures

The deforming bed characteristics of a stratified till assemblage in north East Anglia, UK: investigating controls on sediment rheology and strain signatures
The deforming bed characteristics of a stratified till assemblage in north East Anglia, UK: investigating controls on sediment rheology and strain signatures
The glacial coastal exposures of north Norfolk are a type site for subglacial glaciotectonic deforming bed sediments. This investigation of the lower stratified diamict within the North Sea Drift at West Runton reveals two distinct lamina types. Type 1 laminae are the product of primary extensional glaciotectonism, with ductile, intergranular pervasive shear predominating over brittle shear. Type 2 laminae also exhibit structures that can be attributed to ductile, intergranular pervasive shear and brittle shear, but the lateral continuity of Type 2 laminae and the presence of dropstone—like structures supports a primary subaqueous origin with secondary subglacial deformation.
When coupled with micromorphological analysis, these findings show that ductile, viscous creep mechanisms control sedimentary architecture, and that ‘shear stratification’ in particular, has the potential to affect the rheological properties of the sediment pile and the hydraulic routing of basal water, ultimately influencing critical effective pressure fluctuations and the thresholds controlling the subglacial drainage system.
deforming bed sediments, subglacial, tectonics, sedimentary architecture
0277-3791
123-140
Roberts, D.A.
61adbf03-0dd4-45cb-804f-1a171ac95634
Hart, J.K.
e949a885-7b26-4544-9e15-32ba6f87e49a
Roberts, D.A.
61adbf03-0dd4-45cb-804f-1a171ac95634
Hart, J.K.
e949a885-7b26-4544-9e15-32ba6f87e49a

Roberts, D.A. and Hart, J.K. (2005) The deforming bed characteristics of a stratified till assemblage in north East Anglia, UK: investigating controls on sediment rheology and strain signatures. Quaternary Science Reviews, 24 (1-2), 123-140. (doi:10.1016/j.quascirev.2004.03.004).

Record type: Article

Abstract

The glacial coastal exposures of north Norfolk are a type site for subglacial glaciotectonic deforming bed sediments. This investigation of the lower stratified diamict within the North Sea Drift at West Runton reveals two distinct lamina types. Type 1 laminae are the product of primary extensional glaciotectonism, with ductile, intergranular pervasive shear predominating over brittle shear. Type 2 laminae also exhibit structures that can be attributed to ductile, intergranular pervasive shear and brittle shear, but the lateral continuity of Type 2 laminae and the presence of dropstone—like structures supports a primary subaqueous origin with secondary subglacial deformation.
When coupled with micromorphological analysis, these findings show that ductile, viscous creep mechanisms control sedimentary architecture, and that ‘shear stratification’ in particular, has the potential to affect the rheological properties of the sediment pile and the hydraulic routing of basal water, ultimately influencing critical effective pressure fluctuations and the thresholds controlling the subglacial drainage system.

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More information

Published date: 2005
Additional Information: This paper reports research findings from a studentship topic originated and supervised by me. It uses results from thin-section studies to investigate subglacial processes, and is a key element in the current international debate on the viscous or plastic nature to till deformation, relating to glacier dynamics, and climate change.
Keywords: deforming bed sediments, subglacial, tectonics, sedimentary architecture

Identifiers

Local EPrints ID: 15684
URI: https://eprints.soton.ac.uk/id/eprint/15684
ISSN: 0277-3791
PURE UUID: 549e0e29-25e5-422e-85a4-35b5205c7ae1
ORCID for J.K. Hart: ORCID iD orcid.org/0000-0002-2348-3944

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Date deposited: 25 May 2005
Last modified: 06 Jun 2018 13:13

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Author: D.A. Roberts
Author: J.K. Hart ORCID iD

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