Seabed Mapping and Geohazard Identification in Northern Baffin Bay and Lancaster Sound
Robbie Bennett1, Calvin Campbell1, Steve Blasco1, and John Hughes-Clarke2
1Geological Survey of Canada, Natural Resources Canada, Dartmouth, NS, Canada.
2Ocean Mapping Group, University of New Brunswick, Fredericton, NB, Canada.
Preliminary resource assessments of the Baffin Bay - Lancaster Sound region suggest hydrocarbon resource potential similar to the Beaufort-Mackenzie Basin. Collaboration between the University of New Brunswick and Geological Survey of Canada (GSC) has resulted in the acquisition of multibeam echosounder and sub-bottom profiler data in the area since 2004. In 2008, the GSC and several University partners completed a joint research cruise to Northern Baffin Bay and Lancaster Sound, collecting seabed sediment samples and high resolution seismic reflection data. Integration of these datasets will improve understanding of the shallow geology of the area and will allow identification of potential seabed geohazards.
The shallow geology of Lancaster Sound consists of bedrock overlain by discontinuous glacial till draped by thin glaciomarine sediments. The glacial sediments and bedrock are overlain by <1 to ~10 m of post-glacial sediment. Ice scour is observed in water depths ranging from 110 m to 850 m. Scours typically incise the seabed to a depth of 1 - 4 m, with a maximum observed scour depth of 19 m. Since present day ice berg keels have a maximum draft of about 430 m in the area, ice scour in 850 m water depth likely occurred during the last glaciation when sea level was up to 120 m lower than present and glacial ice was up to 1000 m thick. The ice scour in 850 m of water was incised into glaciomarine sediment and subsequently buried by post-glacial sediments. The transition from glaciomarine to post-glacial sediments in the study area has been AMS dated at greater than ~11,000 Cal yr BP. Glacial fluting in the form of streamlined drumlins and seabed lineations is observed along the southern portion of Lancaster Sound and northeast of Bylot Island in Baffin Bay, indicating ice flow direction from west to east. Flutes rise up to 50 m above the seabed or incise as deep as 50 m into the subsurface, creating slope angles as great as 60°.
One of the largest passive margin earthquakes ever recorded (M 7.3) occurred in Northern Baffin Bay in 1933, however no evidence of recent slope failure was observed during the 2008 expedition. These data show that the shallow geology of Northern Baffin Bay is dominated by widespread glaciogenic debris flow deposition that resulted in the development of a glacially-fed trough mouth fan seaward of Lancaster Sound during the Quaternary. The trough mouth fan forms the upper portion of a large fluvial deltaic fed submarine fan that began to form in the Eocene and suggests the development of a major depocenter throughout the Cenozoic.
Most of the large-scale features observed in the shallow geology of the study area can be attributed to glacial processes that occurred more than 11,000 years ago. There are significant data gaps however and additional data will be required to better understand potential geohazards in this area.
AAPG Search and Discovery Article #90130©2011 3P Arctic, The Polar Petroleum Potential Conference & Exhibition, Halifax, Nova Scotia, Canada, 30 August-2 September, 2011.���������������������������������������������������������������������������������������������������