Glacitectonics : field guide

Abstract

Glacitectonism is defined here as “the deformation (folding, fracturing) caused as a glacier or ice sheet pushes into and overrides pre-existing sequence of sediments and/or bedrock”. This deformation occurs on a variety of scales from delicate micro-scale structures which can only be examined under the microscope, to large macro-scale features on the order of 10’s to 100’s of metres in scale. Glaciers and ice sheets are highly dynamic systems ‘pulsing’ or ‘oscillating’ as they advance or retreat (Benn and Evans, 2010). Consequently, the sediments they leave behind often contain a complex array of cross-cutting structures recording ‘multiple’ or ‘polyphase’ deformation histories that provide a detailed record of glacier evolution and ice sheet dynamics. Analysis and interpretation of the range of structures (folds, faults, tectonic fabrics) developed within proglacially to subglacially deformed sediments provides important information on the character of these glacier-induced deformation events. The application of techniques routinely used by structural geologists enable a greater understanding of the stresses responsible for their development, as well as helping to elucidate the nature of the interplay between ice-marginal to subglacial sedimentation and glacitectonic deformation