Basal ice formation and deformation in central greenland: a review of existing and new ice core data
Published:January 01, 2000
R. Souchez, G. Vandenschrick, R. Lorrain, J.-L. Tison, 2000. "Basal ice formation and deformation in central greenland: a review of existing and new ice core data", Deformation of Glacial Materials, Alex J. Maltman, Bryn Hubbard, Michael J. Hambrey
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In this paper we review, and supplement, existing data to investigate the character, origin and deformation of the basal silty ice of the centre of the Greenland ice sheet as revealed in the Dye3, GRIP and GISP2 cores.
A major process of basal silty ice formation in the central part of Greenland is incorporation of relict non-glacial ice at the base of the ice sheet during its development. The evidence for this can be found in a stable isotope composition study, both in δD and δ18O, in a total gas content and gas composition study, in a comparison of the dielectric conductivity profile and chemical profiles. Ice crystallographic investigations and the study of the isotopic compositions in Nd, Sr and Pb of the mineral particles embedded in the silty ice help to clarify the situation.
The processes proposed to explain the stacked sequence developed in the basal silty ice of these central areas are folding resulting in the interbedding of silty ice and glacial ice, and flow-induced mixing related to circular motion of ice in bedrock depressions with flow separation accompanied by some entrainment of the underlying ice.
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Deformation of Glacial Materials
The flow of glacier ice can produce structures that are striking and beautiful. Associated sediments, too, can develop spectacular deformation structures, and examples are remarkbly well preserved in Quaternary deposits. Although such features have long been recognized, they are now the subject of new attention from glaciologists and glacial geologists.
This collection of papers addresses how the methods for unravelling deformation structures evolved in recent years by structural geologists can be used for glacial materials, and the opportunities offered to structural geologists by glacial materials for studying deformation in rocks.