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TitleThe Late Quaternary History of Greely Fiord and Its Tributaries, West - Central Ellesmere Island
AuthorEngland, J
SourceCanadian Journal of Earth Sciences vol. 27, no. 2, 1990 p. 255-270, https://doi.org/10.1139/e90-025 (Open Access)
Year1990
PublisherCanadian Science Publishing
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf
ProvinceNunavut
NTS120; 39; 49
AreaEllesmere Island; Greely Fiord
Lat/Long WENS -88.0000 -60.0000 83.0000 76.0000
Subjectsgeochronology; surficial geology/geomorphology; marine geology; glacial history; moraines; glaciation; glaciers; glacial stages; ice movement; glaciomarine deposits; glacial deposits; radiocarbon dates; radiometric dates; isostasy; sea level fluctuations; paleogeography; fiords; morphology; marine deposits; Innuitian Ice-sheet; Agassiz Ice Cap; Quaternary
Illustrationsphotographs; sketch maps; tables
AbstractMoraines and meltwater channels mark the limit of the last glaciation that interfingered with the sea around the perimeter of Greely Fiord and its tributaries. The extent of this ice advance was dictated predominantly by its proximity to the sea. Consequently, the large tidewater glaciers at the fiord heads today were so constrained by calving that they advanced only 5 10 km. Similarly, grounding-line deposits from widespread plateau ice caps also terminate just below marine limit. The most extensive outlet glaciers, which advanced 20 35 km beyond present margins, are simply those that had access to the most extensive terrain above marine limit, i.e., the northwest margin of the Agassiz Ice Cap.Forty-one new 14C dates are presented. The onset of the last ice advance must predate marine shells collected from sediments overlying a former grounding line when sea level was 122 m higher than present. At this site, the lowermost shells collected from glaciomarine silts dated 38 070 ± 410BP, whereas a surface sample 13 m above them dated 22 900 ± 190BP. Although both dates may be minimum estimates, they are nonetheless associated with an ice margin that retreated only a few kilometres by 7850BP, suggesting the maintenance of the glacioisostatic loading (and relative sea level) during the interim. Nearby, shells in growth position overlying bedrock confirm that relative sea level was > 83 m asl by 38 010 ± 410BP (minimum age). These marine deposits lie outside the last ice limit and are not overlain by glacigenic sediments.Distal to the last ice limit, Greely Fiord was occupied by the full glacial sea, whose limit is marked by discontinuous beaches and wave-cut benches. The full glacial sea rises from 116 m north of Greely Fiord to a maximum elevation of 148 m bordering its south shore from which it descends to 112 m asl near the head of Caà±on Fiord. Numerous 14C dates on shells collected within 8 m of marine limit show that the full glacial sea remained stable from at least 8400 to 7400BP. Several other shell samples collected ~20 m below marine limit are much older (> 22 000BP). The position of relative sea level between ca. 8000 and > 22 000BP is uncertain; however, stratigraphic evidence for an intervening regression has not been found.The modest extent of the last ice limit encircling Greely Fiord, together with its occupancy by the full glacial sea, is fully compatible with the paleogeography previously reported from northeast Ellesmere Island and northwest Greenland. Furthermore, this data base provides a reinterpretation of a 500 km transect previously reported along west-central Ellesmere Island to the south and affirms that the Innuitian Ice Sheet, defined sensu stricto for the last glaciation, is supplanted by the full glacial Innuitian Sea, which penetrated the Queen Elizabeth Islands, constraining the last ice limit.
GEOSCAN ID5409

 
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