Remnants of the Pleistocene ice sheets in the permafrost zone as an object for paleoglaciological research

Abstract

Glaciogenic ice/sediment complexes which are the remnants of basal layers of the Pleistocene ice sheets and are widespread in the north of Western Siberia are the product of incomplete deglaciation. They are protected from melting by a thin cover mainly composed of till, fluvioglacial sands, solifluction deposits, etc. The main peculiarity of these complexes is the evidence of syngenetic glaciodynamic processes common to both the ice and the sediment components of the complex. They consist primarily of frozen till containing ice cement and lenses of relict glacier ice as well as glaciotectonites, i.e., plucked material from the glacier bed, and dynamorphic ice of non‐glacial origin. The presence of glaciogenic ice/sediment complexes indicates the former existence or regeneration of permafrost beneath the ice sheets. Their structure reflects the nature of ice motion and its impact on the glacier bed and testifies to the great significance of ground ice to glaciodynamic processes. It also indicates fluctuations in the lower limits of the subglacial permafrost, evidently caused by stadial changes in glacier thickness and possible involvement of subpermafrost water under pressure in basal nourishment of the ice sheet. The relict glacier ice found in Western Siberia dates back to the last glaciation of the area. Similar complexes may also be found in Chukotka, Alaska and Canada.