Virginia Brake

The geology of southwestern Nova Scotia is characterized by plutons of varying compositions intruding a Meguma host rock. Onshore, the Shelburne and Barrington Passage plutons intrude the folded Halifax and Goldenville Formations of the Meguma Group. The striped magnetic signature of the Meguma contrasts with a smooth, relatively uniform signature, in some cases positive, associated with the plutons. Previous studies of southwestern Nova Scotia have used gravity and aeromagnetic data to extend interpretations of this onshore lithology into the offshore. More recently, swath bathymetric studies have shown granite bedrock exposed at the surface. This study correlates between the coast and the outer portion of the continental shelf based on forward modelling of magnetic data. A series of profiles constrained by magnetic susceptibility values were used to create 2D cross-sections of lithology. An onshore profile investigates the Shelburne and Barrington Passage plutons. A database of magnetic susceptibility values measured for each lithologic unit provided information on composition and the possible genetic relationships between plutons. These onshore results were extrapolated into the offshore to develop a profile through Mud and Seal Islands to determine the relationship to the onshore plutons and put limits on the extent of the Seal Island Pluton. Areas of positive anomaly on the continental shelf were investigated and linked to the Seal Island profile. The extent of plutons in the offshore has been mapped and correlated to regional geology based on their magnetic anomaly and other geophysical

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Pages: 45
Supervisor: Sonya Dehler