Deformation of the Ross Ice Shelf, Antarctica

摘要: The structural features in the Camp Michigan area on northeastern margin of Ross Ice Shelf, Antarctica, include anticlines, synclines, drag folds, crevasses (some similar to strike-slip faults, others joints) and rifts (extraordinarily wide crevasses). Strain rates were measured surface ice shelf by determining relative positions stakes at various times triangulation. Nye9s flow law for is obtained a systematic simplification generalized proposed Glen. Glen9s laboratory data creep used determine necessary constants law, stresses calculated this basis. A fracture criterion formulated theoretical grounds. This may be described as revolution about hydrostatic stress line space. from strain actively crevassing areas are considered “unstable” greater than actual present. They would cause rupture material if they actually Stresses noncrevassing designated “stable.” plot stable versus unstable shows good agreement with theory. Folding was analyzed accordance method Biot. Even though an exact stability analysis used, predicted wave lengths agree only length youngest folds. extended rocks, but available insufficient definitely establish its validity rocks. principle least work indicates that faults do not necessarily intermediate principal axis plane fault, unavailability precludes formulation usable criterion. rocks amenable study Biot9s theory, lack prohibits wave-length prediction geologic examples.