Cryostratigraphy and Permafrost Evolution in the Lacustrine Lowlands of West-Central Alaska

摘要: The influence of permafrost growth and thaw on the evolution ice-rich lowland terrain in Koyukuk-Innoko region interior Alaska is fundamental but poorly understood. To elucidate this influence, cryostratigraphy properties perennially frozen sediments from three areas are described interpreted terms history. upper part late Quaternary at Koyukuk Innoko Flats comprise organic soils up to 4.5 m thick underlain by silt characterised layered reticulate cryostructures. volume visible segregated ice locally reaches 50 per cent, with lenses 10 cm thick. A conceptual model Late Pleistocene present day identifies four stages yedoma degradation five subsequent aggradation-degradation: (1) partial thawing wedges formation small shallow ponds troughs above wedges; (2) thermokarst lakes polygons; (3) deepening beneath lakes; (4) complete (5) lake drainage; (6) peat accumulation; (7) aggradation drained basins; (8) plateaus; (9) expansion a new generation features. These can occur differing places times, creating highly complex mosaic conditions, complicating predictions landscape response future climatic changes or human impact. Copyright © 2014 John Wiley & Sons, Ltd.