CGRG Bibliography of Canadian Geomorphology
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Author : Furze, M.; and England, J.
Date : 2007.
Title : Evidence from the western Canadian Arctic Archipelago for early breaching of Bering Strait.
Publication : 37th Annual International Arctic Workshop. May 2-4, 2007. Skaftafell, Iceland. Institute of Earth Sciences, University of Iceland, Askja, Iceland.
Issue : Program and Abstracts.
Page(s) : 103.
Abstract
In situ paired valves of Cyrtodaria kurriana (Dunker, 1862), an estuarine species favouring open- water, low-arctic conditions, occur in coastal exposures at the head of Mercy Bay (74°N 119°E), in the western Canadian Arctic Archipelago. These shells occur together with Hiatella arctica and Portlandia arctica and were collected from bottom-set clay stratigraphically related to marine limit (~50 m asl). The modern North American distribution of C. kurriana shows two separate populations, an ‘Atlantic’ population in Baffin Bay and Greenland; and a ‘Beaufort Sea’ population centred on the Mackenzie Delta, extending westward to Bering Strait and eastward to Dolphin & Union Strait. Fossil records from the Atlantic population illustrate its northward migration from a glacial refugium along the New England coast. However, we are unaware of any evidence for a molluscan refugium during the last glaciation (MIS2) within the Arctic Ocean that would have served as a source for the deglacial assemblage noted in Mercy Bay, especially for C. kurriana. Our current evidence suggests that the establishment of the Beaufort Sea population northward to Mercy Bay (well beyond its present range) records the initial resubmergence of Bering Strait and the ingression of Pacific water into the Arctic Ocean. Multiple (concordant) AMS radiocarbon dates on C. kurriana and associated H. arctica valves from the Mercy Bay clay confirm that the species was well established in a large deglacial estuarine embayment by at least 11.5 14C ka BP (13.6 cal ka BP). This represents a minimum age on deglaciation and marine limit as well as, critically, the re-opening of Bering Strait. The occurrence of C. kurriana on Banks Island is at least 500 14Cyears earlier than previously reported dates from marine cores collected in Kotzebue Sound and the Chukchi Sea, at sites where relative sea level past above the critical sill depths (= 45m) leading into Bering Strait. The occurrence of C. kurriana in the western Canadian Arctic Archipelago during deglaciation provides an important constraint on the resubmergence of Bering Strait that include eustatic and possible far-field glacioisostatic and/or tectonic controls. The re-entry of Pacific water into the Arctic Ocean during ongoing deglaciation and relative sea level rise would have had significant impart on the evolving biogeography of this region (both terrestrial and marine flora and fauna). Furthermore, this new oceanic exchange would have likely occasioned both climatic and oceanographic responses in the Arctic Ocean Basin immediately prior to the Younger Dryas
Bibliography of Canadian Geomorphology