2D Depth Seismic Imaging in the Gaspé Belt, a Structurally Complex Fold and Thrust Belt in the Northern Appalachians, Québec, Canada

Abstract

The Gaspé Belt is located in the Québec part of the Northern Appalachians. Its present geometry is complicated by the fact that the rocks were deposited on and deformed over previously structured fold and thrust belt. The objective of the recent (2000–2002) seismic survey of the Ministère des Ressources Naturelles et de la Faune du Québec was to obtain new seismic cross sections in this complex fold belt in order to better interpret its structural geometry. The surface geology displays high complexity, with sub-horizontal to sub-vertical bedding, open to tight folds and normal, reverse and strikeslip faults. A depth seismic imaging study was carried out on a 2D cross section through the Gaspé Belt by integrating all available geological data throughout the processing procedure. The challenge of seismic processing was the determination of the velocity model used for depth migration. For this case study, various methods for velocity model determination, from interpretative estimation to advanced travel time inversion, were applied and the combined interpretations of these depth migrated images were used to confirm a recent structural model of Acadian foreland thrust and fold belt in the Gaspé Peninsula.