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Salt Canopies of the Central Scotian Slope and Their Impact from Sediment Transfer into the Deep-Water Areas off Nova Scotia, Canada

Kendell, Kris L.1; Deptuck, Mark E.1; Smith, Brenton M.1
1 Canada-Nova Scotia Offshore Petroleum Board, Halifax, NS, Canada.

The Scotian Basin has undergone a complex sedimentary history strongly influenced by salt tectonics. Spatial variations in salt-sediment interaction across the margin have produced several distinct salt tectonic domains documented in previous studies. This paper focuses on the central Scotian Slope, where a major salt canopy system extends up to 60 km seaward of the thickest parts of the Sable Subbasin, an important post-Jurassic depocenter. A key uncertainty in deepwater exploration in this area is the presence and distribution of turbidite reservoirs. Improved understanding of the canopy system may help in this regard. The canopy system covers about 11 500 km2 of the Scotian Slope and is poorly understood despite the fact that it has important implications for the transfer of sediment into deepwater and development of potential hydrocarbon-bearing structures.

Initial sediment loading above autochthonous Triassic salt in this area appears to have initiated the development of widespread expulsion rollover monoclines and salt withdrawal minibasins separated by salt feeder systems. There appears to be a strong association between areas with the highest density of salt feeders and regions of the slope where prominent detachment (Roho) systems developed. Detachment in such areas is interpreted to have taken place above expansive salt canopies that coalesced from underlying salt stocks. Major roho systems are recognized both on the eastern and western portions of the canopy system. Salt sediment interaction in areas with lower density of salt feeders produce a wide variety of structures including expulsion rollovers, salt withdrawal minibasins and subordinate amounts of detachment. Both of these expulsion processes have generated the large scale canopy system as seen on present day seismic profiles that has been reactivated by Tertiary depositional systems producing an even younger suite of potential hydrocarbon traps.

Salt contact maps and paleogeographic reconstructions have helped unravel the complex history of salt tectonics despite the limited amount of well control in this area. These maps combined with mapping of base salt highs have resulted in the identification of possible sediment fairways to deepwater.

 

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009