Subglacial deformation and water-pressure cycles as a key for understanding ice stream dynamics: evidence from the Late Ordovician succession of the Djado Basin (Niger).
27 pages International audience Subglacial deformation is crucial to reconstructing glacier dynamics. Sediments associated with the Late Ordovician ice sheet in the Djado Basin, Niger, exhibit detailed structures of the subglacial shear zone. Three main types of subglacial shear zones (SSZ) are disc...
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ftunivbourgogne:oai:HAL:hal-00509918v1 2024-01-07T09:43:59+01:00 Subglacial deformation and water-pressure cycles as a key for understanding ice stream dynamics: evidence from the Late Ordovician succession of the Djado Basin (Niger). Denis, Michaël Guiraud, Michel Konaté, Moussa Buoncristiani, Jean-François Biogéosciences UMR 6282 (BGS) Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS) Département de Géologie Université Abdou Moumouni Niamey Part of this work funded by research grants provided by the TOTAL ‘‘Projets Nouveaux Afrique'' and research allocation from the Ministère de l'Education Nationale, de la Recherche et de la Technologie. 2010-09 https://hal.science/hal-00509918 https://doi.org/10.1007/s00531-009-0455-z en eng HAL CCSD Springer Verlag info:eu-repo/semantics/altIdentifier/doi/10.1007/s00531-009-0455-z hal-00509918 https://hal.science/hal-00509918 doi:10.1007/s00531-009-0455-z ISSN: 1437-3254 EISSN: 1437-3262 International Journal of Earth Sciences https://hal.science/hal-00509918 International Journal of Earth Sciences, 2010, 99 (6), pp.1399-1425. ⟨10.1007/s00531-009-0455-z⟩ Hirnantian Soft-bed deformation Subglacial shear zones Subglacial water pressure Ice/bed decoupling Ice stream [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology info:eu-repo/semantics/article Journal articles 2010 ftunivbourgogne https://doi.org/10.1007/s00531-009-0455-z 2023-12-12T23:37:23Z 27 pages International audience Subglacial deformation is crucial to reconstructing glacier dynamics. Sediments associated with the Late Ordovician ice sheet in the Djado Basin, Niger, exhibit detailed structures of the subglacial shear zone. Three main types of subglacial shear zones (SSZ) are discriminated. The lowermost SSZ, developed on sandstones, displays Riedel macrostructures and cataclastic microstructures. These resulted from brittle deformation associated with strong glacier/bed coupling and low porewater pressure. Where they developed on a clay-rich bed, the overlying SSZ display S–C to S–C' fabrics, sheath folds, and dewatering structures. These features indicate high ductile shear strain and water overpressure. On finegrained sand beds, the SSZ exhibit homogenized sand units with sand stringers, interpreted as fluidized sliding beds. The succession of subglacial deformation processes depends on fluid-pressure behavior in relation to subglacial sediment permeability. Fluid overpressure allows subglacial sediment shear strength and ice/bed coupling to be lowered, leading to ice streaming. Article in Journal/Newspaper Ice Sheet Université de Bourgogne (UB): HAL International Journal of Earth Sciences 99 6 1399 1425 |
institution |
Open Polar |
collection |
Université de Bourgogne (UB): HAL |
op_collection_id |
ftunivbourgogne |
language |
English |
topic |
Hirnantian Soft-bed deformation Subglacial shear zones Subglacial water pressure Ice/bed decoupling Ice stream [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology |
spellingShingle |
Hirnantian Soft-bed deformation Subglacial shear zones Subglacial water pressure Ice/bed decoupling Ice stream [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology Denis, Michaël Guiraud, Michel Konaté, Moussa Buoncristiani, Jean-François Subglacial deformation and water-pressure cycles as a key for understanding ice stream dynamics: evidence from the Late Ordovician succession of the Djado Basin (Niger). |
topic_facet |
Hirnantian Soft-bed deformation Subglacial shear zones Subglacial water pressure Ice/bed decoupling Ice stream [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology |
description |
27 pages International audience Subglacial deformation is crucial to reconstructing glacier dynamics. Sediments associated with the Late Ordovician ice sheet in the Djado Basin, Niger, exhibit detailed structures of the subglacial shear zone. Three main types of subglacial shear zones (SSZ) are discriminated. The lowermost SSZ, developed on sandstones, displays Riedel macrostructures and cataclastic microstructures. These resulted from brittle deformation associated with strong glacier/bed coupling and low porewater pressure. Where they developed on a clay-rich bed, the overlying SSZ display S–C to S–C' fabrics, sheath folds, and dewatering structures. These features indicate high ductile shear strain and water overpressure. On finegrained sand beds, the SSZ exhibit homogenized sand units with sand stringers, interpreted as fluidized sliding beds. The succession of subglacial deformation processes depends on fluid-pressure behavior in relation to subglacial sediment permeability. Fluid overpressure allows subglacial sediment shear strength and ice/bed coupling to be lowered, leading to ice streaming. |
author2 |
Biogéosciences UMR 6282 (BGS) Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS) Département de Géologie Université Abdou Moumouni Niamey Part of this work funded by research grants provided by the TOTAL ‘‘Projets Nouveaux Afrique'' and research allocation from the Ministère de l'Education Nationale, de la Recherche et de la Technologie. |
format |
Article in Journal/Newspaper |
author |
Denis, Michaël Guiraud, Michel Konaté, Moussa Buoncristiani, Jean-François |
author_facet |
Denis, Michaël Guiraud, Michel Konaté, Moussa Buoncristiani, Jean-François |
author_sort |
Denis, Michaël |
title |
Subglacial deformation and water-pressure cycles as a key for understanding ice stream dynamics: evidence from the Late Ordovician succession of the Djado Basin (Niger). |
title_short |
Subglacial deformation and water-pressure cycles as a key for understanding ice stream dynamics: evidence from the Late Ordovician succession of the Djado Basin (Niger). |
title_full |
Subglacial deformation and water-pressure cycles as a key for understanding ice stream dynamics: evidence from the Late Ordovician succession of the Djado Basin (Niger). |
title_fullStr |
Subglacial deformation and water-pressure cycles as a key for understanding ice stream dynamics: evidence from the Late Ordovician succession of the Djado Basin (Niger). |
title_full_unstemmed |
Subglacial deformation and water-pressure cycles as a key for understanding ice stream dynamics: evidence from the Late Ordovician succession of the Djado Basin (Niger). |
title_sort |
subglacial deformation and water-pressure cycles as a key for understanding ice stream dynamics: evidence from the late ordovician succession of the djado basin (niger). |
publisher |
HAL CCSD |
publishDate |
2010 |
url |
https://hal.science/hal-00509918 https://doi.org/10.1007/s00531-009-0455-z |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
ISSN: 1437-3254 EISSN: 1437-3262 International Journal of Earth Sciences https://hal.science/hal-00509918 International Journal of Earth Sciences, 2010, 99 (6), pp.1399-1425. ⟨10.1007/s00531-009-0455-z⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1007/s00531-009-0455-z hal-00509918 https://hal.science/hal-00509918 doi:10.1007/s00531-009-0455-z |
op_doi |
https://doi.org/10.1007/s00531-009-0455-z |
container_title |
International Journal of Earth Sciences |
container_volume |
99 |
container_issue |
6 |
container_start_page |
1399 |
op_container_end_page |
1425 |
_version_ |
1787425286813384704 |