Stratigraphy and palaeoenvironments of Richards Island and the eastern Beaufort continental shelf during the last glacial-interglacial cycle

• Main Author: Julian Murton
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2009
• Subjects: Uncategorised value; Beaufort Shelf; Ice; Ice Sheet; permafrost; Porcupine River; Richards Island
• Online Access: https://figshare.com/articles/journal_contribution/Stratigraphy_and_palaeoenvironments_of_Richards_Island_and_the_eastern_Beaufort_continental_shelf_during_the_last_glacial-interglacial_cycle/23318948

The Pleistocene lithostratigraphy exposed on northern Richards Island comprises seven units that correlate with the offshore seismostratigraphy of the eastern Beaufort Continental Shelf. Land-sea correlations, cryostratigraphic observations and proxy indicators of environmental change provide a record of palaeoenvironmental history that commences before the last glacial-interglacial cycle. After the high sea-level stand of the Last (Sangamonian) Interglaciation, marine regression exposed a large area of the eastern Beaufort Shelf to cold subaerial conditions and permafrost aggradation. Northward progradation of a braided river system was abruptly replaced by aeolian activity, probably as a result of diversion of the palaeo-Porcupine River by the advancing Laurentide Ice Sheet during the Late Wisconsinan. Glaciation of Richards Island by the Mackenzie palaeo-ice stream was brief (sometime between ~22 000 and 16 000 cal. yr BP), and deglaciation had certainly commenced by 14 300 cal. yr BP and perhaps by ~16 000 cal. yr BP or earlier. Major fluvial erosion during the Last Glacial-Interglacial Transition incised cross-shelf valleys and formed a regional erosion surface. The Holocene marine transgression trimmed some of the erosion surface and offshore, covered it with marine deposits.