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LOCAL ICE ON WESTERN MELVILLE ISLAND, NWT, CANADA
NIXON, CHANTEL F University of Alberta.
England, John H University of Alberta.
Understanding the dynamics of former ice sheets and relative sea level in the western Canadian Arctic Archipelago is important for improving models of past climates and coastline stability, and for providing records of sediment transport to the adjacent Arctic Ocean Basin, whose depositional history is of growing international interest. At present, the late Quaternary glacial and sea level history of the Canadian High Arctic is best documented for the mountainous eastern Queen Elizabeth Islands (Dyke et al., 2002; England, et al., 2000) and the next stage of research has recently been initiated for the expansive lowlands of the western Canadian Arctic Archipelago. Western Melville Island has been selected because it supported a local ice cap (Hodgson, 1992), which flanked the adjacent Innuitian and Laurentide ice sheets during the Last Glacial Maximum (LGM). Research objectives for this study include determining the spatial and temporal relationship between these three ice masses during the LGM and also documenting the resulting magnitude and pattern of postglacial sea level change around the former Melville Island ice cap.
During the first season (2003) fieldwork concentrated on Inner Liddon Gulf, the largest marine embayment on SE Melville Island. This area was occupied by the SE margin of the local ice cap and during deglaciation, a marine corridor extended from southwest Hecla and Griper Bay to Liddon Gulf, splitting the island in two. A large ice-contact delta deposited by the ice cap marks marine limit (65 meters above sea level). Based on sea level curves constructed for inner Hecla and Griper Bay (Hanson, 2003; ~50 km to the northeast) the projected age of the 65 m shoreline could be greater than 11.5 ka BP. Shell samples relating to the 65m sea level and other lower, postglacial sea levels were collected and submitted for radiocarbon analysis.
Evidence for a recent transition from emergence to submergence along this coastline is recorded by coarse gravel onlapping vegetated coastal mudflats. Driftwood collected along the coast of Inner Liddon Gulf is also being dated and will help to test whether modern sea level is encroaching on beaches containing older wood (late Holocene) and mixing it with modern (anthropogenic) material. Driftwood at intermediate elevations will also be dated in order to construct postglacial relative sea level curves for this area.
Plans for 2004 fieldwork on western Melville Island include surveying and dating marine limits and postglacial shorelines throughout fiords flanking the western margin of the former local ice cap where both glacigenic and raised marine sediments have been cited. Currently, only three radiocarbon dates are available from the fiords of western Melville Island (Hodgson, 1992). These indicate that outlet glaciers from the local ice cap still occupied the fiords during the Younger Dryas Geochron (between 10 and 11 ka BP). This fieldwork will allow for further investigation of the response of the local ice cap on Melville Island to this climatic deterioration. The dynamics of the Melville Island ice cap will also contribute to a better understanding of the late glacial climate at high latitudes, and what role the ice played in the depositional record of the adjacent Arctic Ocean and its relationship to the NE extremity of Beringia.
Hodgson, D. A., 1992, Quaternary Geology of Western Melville Island, Northwest Territories: Geological Survey of Canada Paper 89-21.
England, J., Smith, I. R., and Evans, D. J. A., 2000, The last glaciation of east-central Ellesmere Island, Nunavut: ice dynamics, deglacial chronology, and sea level change: Canadian Journal of Earth Sciences, v. 37, p. 1355-1371.
Dyke, A. S., Andrews, J. T., Clark, P. U., England, J. H., Miller, G. H., Shaw, J., and Veilletter, J. J., 2002, The Laurentide and Innuitian ice sheets during the Last Glacial Maximum: Quaternary Science Reviews, v. 21, p. 9-31.
Hanson, M. A., 2003, Late Quaternary Glaciation, Relative Sea Level History and Recent Coastal Submergence of Northeast Melville Island, Nunavut: Unpublished thesis, Department of Earth and Atmospheric Sciences, University of Alberta.
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