CGRG Bibliography of Canadian Geomorphology
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Author : Bennett, R.; Blasco, S.; MacLean, B.; Rochon, A.; Hughes Clarke, J.; Beaudoin, J.; Bartlett, J.; Jenner, K.; and Schell, T.
Date : 2005.
Title : Paleoceanography, seabed morphology and geologic framework of the NW Passage.
Publication : Arctic Net 2005 Programme. Annual Scientific Meeting, December 13-16, 2005. Banff, Alberta
Issue :
Page(s) : 19-20.
Abstract
Thirty kHz multibeam echosounder and 3.5 kHz sub-bottom profiler data were continuously collected as CCGS Amundsen transited the NW Passage during the 2004 and 2005 ArcticNet field programs. These geophysical data in conjunction with sediment cores collected at key sites are being used to map seabed morphology, interpret the regional geologic framework and to investigate the paleoceanographic history of the NW Passage over the past 20,000 years to meet the objectives of project 1.6. The known, but very patchy, geologic framework of the seabed of the NW Passage inter-channels consists of bedrock base overlain by discontinuous glacial till. Thin glaciomarine sediments drape the till and/or bedrock. Discontinuous localized accumulations of Holocene sediment infill depressions with thickness varying from <1 to 10 m. Amundsen geophysical data has significantly extended this stratigraphy to new areas not previously surveyed. Sediment coring of this sequence of sediments at key sites identified on sub-bottom profiles will define the geological framework of the inter-channel areas. Sediment core sampling is currently focused on the localized thick Holocene deposits to determine the waxing and waning of the sea-ice regime over the past 10,000 years. To date, seven piston cores ranging in length from 1.3 to 7.0 m have been acquired for paleoceanographic reconstructions. The first piston core to be analyzed was collected in Lancaster Sound during 2004. The core has been split, logged, described and sub-sampled for detailed sedimentological, chronological and paleoceanographic analyses. Initial results indicate the core successfully penetrated about 5.3 m of undisturbed Holocene sediment covering the last 10,700 – 10,500 cal years BP; confirming the interpretation of the geophysical data. Regional geological mapping of the NW Passage to locate Holocene sediment depocentres has resulted in the identification of a variety of geomorphic features on the seabed that shed light on glacial and recent processes responsible for shaping the morphology of the NW Passage. In 2004, streamlined linear fluting features were mapped in about 400m water depth in Amundsen Gulf. These features are on strike with similar terrestrial features on Victoria Island to the east. Multibeam and subbottom mapping coverage of the Amundsen Gulf flutes was expanded during the 2005 field program revealing a widespread distribution of these features. Flutings with associated current scour were observed from multibeam data close to the CA18 mooring site in southern Amundsen Gulf. Smaller scale flutings were also observed in the eastern Canadian Arctic in PondInlet and Eclipse Sound. Processes responsible for the generation of these features include glacial ice streaming and/or high velocity subglacial meltwater discharge. In addition, gas vents or pockmarks have been observed in the seabed of Barrow Strait in water depths of about 300m. Sub-bottom profiles over the Barrow Strait pockmarks reveals that these features are actively venting fluids.
Bibliography of Canadian Geomorphology