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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
earth and planetary sciences
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)
International Journal of Earth Sciences, Volume 99, No. 6, Year 2010
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Description
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 pore-water 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 fine-grained 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. © 2009 Springer-Verlag.
Authors & Co-Authors
Denis, Michaël
France, Dijon
Biogéosciences Bgs
France, Paris
Total S.a.
Guiraud, Michael
France, Dijon
Biogéosciences Bgs
Konaté, Moussa
Niger, Niamey
Universite Abdou Moumouni
Buoncristiani, Jean François
France, Dijon
Biogéosciences Bgs
Statistics
Citations: 80
Authors: 4
Affiliations: 3
Identifiers
Doi:
10.1007/s00531-009-0455-z
ISSN:
14373254
e-ISSN:
14373262
Research Areas
Environmental
Study Locations
Niger