--> Abstract: Cenozoic Sedimentation Processes of the Central Scotian Slope, by Kent W. Simpson, David C. Mosher, John M. Stewart, and Grant D. Wach; #90039 (2005)

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Cenozoic Sedimentation Processes of the Central Scotian Slope

Kent W. Simpson1, David C. Mosher2, John M. Stewart3, and Grant D. Wach1
1 Dalhousie University, Halifax, NS
2 Geological Survey of Canada Atlantic, Dartmouth, NS
3 McGregor GeoScience Ltd, Halifax, NS

Detailed 2D and 3D seismic reflection data provide the sequence stratigraphic framework and geomorphologic information to allow interpretation of the sedimentation history of an area on the central Scotian Slope, deep water of offshore Nova Scotia. In this context, these data provide for assessment of the relative significance of varying sedimentary processes and ultimately assessment of the contribution of mass-wasting to progradation of a classic passive continental margin.

Dominant depositional styles are off-shelf progradation by low-stand glacial outwash turbidity current activity and high-stand interglacial hemipelagic drape. Occasional mass transport deposits (MTD) have been interpreted, initially by their appearance in profile view: chaotic seismic reflectors bounded by upper and lower irregular surfaces. One particular MTD of probable Pleistocene age is correlated throughout the 3D seismic cube (25 km x 60 km) in water depths of 750 - 2000 m. A render of the surface of this deposit shows a blocky debris flow, with individual blocks sometimes as large as 250 metres in diameter. Coherent reflectors, interpreted to represent turbidites, thin downslope and drape underlying morphologies created by mass-transport processes and salt migration. A layer-bound fault system is apparent in section, interrupting Cenozoic sediments, including the MTDs. Surface renders show this fault system to be polygonal in form, suggesting a syneresis process for their formation. As the fault system cuts much of the studied stratigraphy, MTDs are likely unrelated to this faulting. The modern seafloor shows evidence of downslope-trending gullies and channels, suggesting off-shelf sedimentation in mass-transport processes continued into the Holocene.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005