Multiple glaciations and marine transgressions, western Kennedy Channel, Northwest Territories, Canada
Along a 70 km section of western Kennedy Channel three prominent weathering zones are identified and serve to differentiate major events in the Quaternary landscape. The oldest zone (Zone 111b) is characterized by a deeply weathered, erratic‐free terrain which extends from the mountain summits down...
| Published in: | Boreas |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Wiley
1981
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1111/j.1502-3885.1981.tb00470.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1502-3885.1981.tb00470.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1502-3885.1981.tb00470.x |
| Summary: | Along a 70 km section of western Kennedy Channel three prominent weathering zones are identified and serve to differentiate major events in the Quaternary landscape. The oldest zone (Zone 111b) is characterized by a deeply weathered, erratic‐free terrain which extends from the mountain summits down to ca. 470 m above sea level. This zone shows no evidence of former glacierization. Zone 111a extends from ca. 470 to 370m above sea level and is characterized by sparse granite, gneiss and quartzite erratics amongst weathered bedrock and extensive, oxidized colluvium. The Precambrian provenance and uppermost profile of these erratics reflect the maximum advance of the northwest Greenland Ice Sheet onto northeastern Ellesmere Island. These uppermost erratics along western Kennedy Channel decrease in elevation southward and suggest that the former Greenland ice was thickest in the direction of the major outlet of Petermann Fiord. No evidence of a former ice ridge in Nares Strait was observed. Zone II is marked by the moraines of the outermost Ellesmere Island ice advance which form a prominent morpho‐stratigraphic boundary where they cross‐cut the zone of Greenland erratics at ca. 250–350 m above sea level. These moraines show advanced surface weathering and ice recession from them is associated with a pre‐Holocene shoreline at 162 m above sea level. Late Wisconsin/Würm glacial deposits, equivalent to Zone I, were not observed in the lower valleys bordering Kennedy Channel. The outermost Ellesmere Island ice advance (Zone II) is radiometrically bracketed by 14 C dates on in situ shells from subtill and supratill marine units which are 40,350±750 and>39,000 B.P., respectively. Amino acid age estimates on the same shell samples and others from similar stratigraphic positions all suggest ages of >35,000 B.P. Stratigraphically and chronologically this ice advance is correlated with the outermost Ellesmere Island ice advance 20–40 km to the north which formed small ice shelves when the relative sea level was ca. 175 m ... |
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