CGRG Bibliography of Canadian Geomorphology
Search Results
Author : Blasco, S.M.; Bennett, R.; Hughes-Clarke, J.; Bartlett, J.; and Shearer, J.M.
Date : 2005.
Title : 3-D multibeam mapping reveals geological processes associated with fluted seabed, pockmarks, mud volcanoes, deep water ice scours and slump feature in the Beaufort Sea–Amundsen Gulf.
Publication : Joint Meeting of the Geological Association of Canada, the Mineralogical Association of Canada, the Canadian Society of Petroleum Geologists and the Canadian Society of Soil Sciences. May 15-18, 2005. Studley Campus of Dalhousie University, Halifax, Nova Scotia.
Issue :
Page(s) :
Abstract
During the summers of 2003-04, the research icebreaker CCGS Amundsen and coastal vessel CCGS Nahidik were used to collect digital, georeferenced marine geophysical data in the Beaufort Sea and Amundsen Gulf as part of the Beaufort Shelf seabed stability and Canadian Arctic Shelf Exchange Studies (CASES). A 30 kHz Kongsberg-Simrad EM300 multibeam echosounder and 3.5 kHz Knudsen 320R subbottom profiler were hull mounted on CCGS Amundsen. A 300 kHz Kongsberg-Simrad EM3000 multibeam echosounder was mounted on a launch on CCGS Nahidik which towed a 4 kHz Seistec subbottom profiler. Multibeam and subbottom profilers on each ship were used in combination for high-resolution 3-D mapping of seabed features. Streamlined fluting and crag-and-tail features in about 400 m of water on the bottom of Amundsen Gulf are on strike and similar in morphology to features on Victoria Island to the east. These features may be the product of a Laurentide ice stream or of high-velocity subglacial meltwater discharge. Ice scours with irregular paths have been observed to water depths of 400 m. Present day sea-ice pressure ridge keels scour to water depths of 55 m on the Beaufort Shelf. Low stand late Pleistocene sea level would have allowed pressure ridge keels to generate ice scours to approximately 175 m. The deep water events may be the product of iceberg calving from the retreating Amundsen Gulf ice stream. A large scale 9 km wide and 60 m deep submarine slump scar located on the Beaufort Shelf edge in about 250 m water depth may have occurred as a result of downslope creep failure. A localized concentration of several hundred active pockmark craters on the Beaufort Shelf may be forming by episodic, explosive gas venting. There is no evidence of collapse features around the craters. Some previously identified pingo-like features on the Beaufort Shelf may be mud volcanoes. Observed crestal methane venting associated with mud flows suggests seepage of gas, fluids and mud from depth.
Bibliography of Canadian Geomorphology