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3-D Seismic Interpretation of Deepwater Cenozoic Stratigraphy, Erosion Systems and Salt Tectonics of the Central Scotian Slope Offshore Nova Scotia

Adam W. MacDonald1, David J.W. Piper2, David C. Mosher2, and Pierre Jutras1
1 Saint Mary's University, Halifax, NS
2 Geological Survey of Canada Atlantic, Dartmouth, NS

The Cenozoic stratigraphy of the Central Scotian Slope, part of the Mesozoic-Cenozoic Scotian Basin, is studied to understand influences of sea level change, salt tectonics and shelf-crossing glaciations on sedimentation patterns in a northern hemisphere passive continental margin setting. Recent 2D and 3D seismic data, biostratigraphy and geophysical logs provide new insights into the depositional history of this region. In the study area, Cenozoic strata have been cannibalized by deeply (500 m) eroded canyon systems from the Pliocene to the late Pleistocene. Within this canyon system, broad intercanyon regions are relatively complete in their stratigraphic succession. These regions provide an opportunity to study the effects of erosional systems and salt tectonics on sedimentation patterns and stratigraphy through the Cenozoic.

Cenozoic strata can be subdivided into two large scale successions. The Paleogene to Early Oligocene high stand system tract and the Early Oligocene to present low stand system tract, separated by a major Oligocene unconformity. Generally, the high stand setting trapped deltaic deposition on the shelf, while deepwater sedimentation was dominated by thick sequences of muds, silts and fine sands. The low stand system setting shows numerous channel and canyon forming events and remnants of turbidite systems, with well developed overbank levee deposits, stacked sediment waves and mass transport deposits. Detailed seismic facies analysis on the Cenozoic stratigraphy reveals a complex variety of extensional halokinetic structures. The timing of salt mobility is constrained in the stratigraphic framework by recognizing periods of stratigraphic uplift, onlap, erosion and faulting. Understanding low stand morphologies and sedimentation patterns is critical to deepwater reservoir exploration.

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