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Seismic images of a tectonic subdivision of the Greenville Orogen beneath lakes Ontario and Erie

January 1, 1994

New seismic data from marine air-gun and Vibroseis profiles in Lake Ontario and Lake Erie provide images of subhorizontal Phanerozoic sediments underlain by a remarkable series of easterly dipping reflections that extends from the crystalline basement to the lower crust. These reflections are interpreted as structural features of crustal-scale subdivisions within the Grenville Orogen. Broadly deformed, imbricated, and overlapping thrust sheets within the western Central Metasedimentary Belt are succeeded to the west by a complex zone of easterly dipping, apparent thrust faults that are interpreted as a southwest subsurface extension of the boundary zone between the Central Metasedimentary Belt and the Central Gneiss Belt. The interpreted Central Metasedimentary Belt boundary zone has a characteristic magnetic anomaly that provides a link from the adjacent ends of lakes Ontario and Erie to structures exposed 150 km to the north. Less reflective, west-dipping events are interpreted as structures within the eastern Central Gneiss Belt. The seismic interpretation augments current tectonic models that suggest the exposed ductile structures formed at depth as a result of crustal shortening along northwest-verging thrust faults. Relatively shallow reflections across the boundary region suggest local, Late Proterozoic extensional troughs containing post-Grenville sediments, preserved possibly as a result of pre-Paleozoic reactivation of basement structures.

Citation Information

Publication Year 1994
Title Seismic images of a tectonic subdivision of the Greenville Orogen beneath lakes Ontario and Erie
DOI 10.1139/e94-023
Authors D. A. Forsyth, B. Milkereit, A. Davidson, S. Hanmer, Deborah R. Hutchinson, W. J. Hinze, R.F. Mereu
Publication Type Article
Publication Subtype Journal Article
Series Title Canadian Journal of Earth Sciences
Index ID 70134541
Record Source USGS Publications Warehouse
USGS Organization Coastal and Marine Geology Program; Woods Hole Coastal and Marine Science Center