Michael Giles

Geological problems with offshore Nova Scotia are associated with complex salt deformation beneath the shelf and slope. Features in this area record highly variable tectono-sedimentary environments with high rates of sedimentation and progradation during the Jurassic and Early Cretaceous. These features have impacted petroleum exploration; particularly seismic imaging and hampers the structural interpretation of basement morphology beneath the rift-related salt basins. To address these problems innovative structural modelling techniques were coupled with interpretation of public seismic data from offshore Nova Scotia. Dynamically scaled analogue models consisting silica sand and silicone rubber simulate sedimentation, salt mobilization and deformation of the brittle overburden sediments and ductile salt.

Recent hydrocarbon exploration and scientific activity along on the southwestern Scotian Slope has provided the opportunity to improve the understanding of past and present sedimentation patterns and processes recorded on the slope. Eight seismic horizons in the Harrington 3D Cube were correlated in the dip and strike directions across the study area, creating the stratigraphic framework. The scope of this study is to explore the Cenozoic stratigraphy in terms of the mass transport complexes (MTC) and discern how these complexes have affected the evolution of the Scotian margin with particular emphasis within the Harrington Block (3D seismic cube provided by EnCana Corporation).

Four seismic facies (A, B, C, and D) were identified in the Barrington 3D seismic cube were used to distinguish and describe six units within the cube. Seismic facies interpretation of the cube demonstrates that the upper portion of the Scotian Slope was comprised of chaotic, discontinuous reflectors suggesting that the Cenozoic strata of the primarily records successive MTC deposits. Four of the six units observed in this study were identified as MTC deposits.

Four triggering mechanisms have been suggested to initiate MTC's along the Scotian margin: seismicity, glacial sediment overloading, gas hydrates and salt tectonics. Most likely the triggering events for these MTC's are some combination of the four mechanisms that cause instability along the Slope. The results and interpretation of these MTC deposits will help to improve the understanding of deep water basin development, slope evolution and assist in geo-hazard assessment of offshore Nova Scotia.

Keywords: mass transport complexes (MTC), 3D seismic stratigraphy, seismic facies, Scotian Slope, Cenozoic stratigraphy, triggering mechanisms, slope processes, geo-hazards.
Pages: 63
Supervisor: David Mosher / Grant Wach