--> Abstract: Structural Interpretation and Seismic Imaging of the Gaspé Belt, a Structurally Complex Fold and Thrust Belt in the Northern Appalachians, by Donna Kirkwood, Eric Desaulniers, Anne Jardin, Martin Beche, and Jean-Yves Laliberte; #90039 (2005)

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Structural Interpretation and Seismic Imaging of the Gaspé Belt, a Structurally Complex Fold and Thrust Belt in the Northern Appalachians

Donna Kirkwood1, Éric Desaulniers1, Anne Jardin2, Martin Bèche2, and Jean-Yves Laliberté3
1 Université Laval, Sainte-Foy, QC
2 Institut Français du Pétrole, Rueil-Malmaison, France
3 Ministère des Ressources naturelles, Faunes et Parcs du Québec,

The Gaspé Peninsula is located in the Québec part of the Northern Appalachians and contains the most complete Mid-Paleozoic stratigraphic sequence of the Canadian Appalachians. Rocks of the Gaspé Basin rest unconformably on a Mid-Ordovician Taconian fold and thrust belt. They were in turn deformed by the mid-Devonian Acadian orogeny and are now part of the Gaspé Belt. The present geometry of the belt is thus complicated by the fact that the rocks were deposited on and deformed over a previously structured foothills type basement.

An integrated structural and seismic study was undertaken in the Gaspé Peninsula to test the structural framework for the mid-Devonian Acadian orogeny along a regional mega-transect in the central part of the Gaspé Peninsula. Seismic reflection data were acquired in 2002 for the Secteur Énergie of Ministère des Ressources naturelles, Faunes et Parcs du Québec. The challenge here was to obtain reliable seismic images in this complex foothills context in order to better interpret the subsurface structural style of the Acadian belt as well as the underlying Taconian basement. The surface geology displays high complexity, with sub-horizontal to sub-vertical bedding, open to tight folds and normal, reverse and strike-slip faults. The rocks also present strong lateral velocity contrasts and seismic data show low signal to noise ratio. A new method was developed to reprocess the seismic reflection data by introducing geological and structural knowledge into the velocity model building procedure in order to produce more realistic seismic images. Pre and post stack migration time and depth seismic images were obtained and provided additional information about the nature of faults, the architecture of sedimentary layers and the structural geometry related to deep thrusts.

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