Seismic images of a Grenvillian terrane boundary

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A series of gently dipping reflection zones extending to mid-crustal depths is recorded by seismic data from Lakes Ontario and Erie. These prominent reflection zones define a broad complex of southeast-dipping ductile thrust faults in the interior of the Grenville orogen. One major reflection zone provides the first image of a proposed Grenvillian suture—the listric boundary zone between allochthonous terranes of the Central Gneiss and Central Metasedimentary belts. Curvilinear bands of reflections that may represent "ramp folds" and "ramp anticlines" that originally formed in a deep crustal-scale duplex abut several faults. Vertical stacking of some curvilinear features suggests coeval or later out-of-sequence faulting of imbricated and folded thrust sheets. Grenvillian structure reflections are overlain by a thin, wedge-shaped package of shallow-dipping reflections that probably originates from sediments deposited in a local half graben developed during a period of post-Grenville extension. This is the first seismic evidence for such extension in this region, which could have occurred during terminal collapse of the Grenville orogen, or could have marked the beginning of pre-Appalachian continental rifting.

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Publication type Article
Publication Subtype Journal Article
Title Seismic images of a Grenvillian terrane boundary
Series title Geology
DOI 10.1130/0091-7613(1992)020<1027:SIOAGT>2.3.CO;2
Volume 20
Issue 11
Year Published 1992
Language English
Publisher Geological Society of America
Publisher location Boulder, CO
Contributing office(s) Woods Hole Coastal and Marine Science Center
Description 4 p.
First page 1027
Last page 1030
Country United States
Other Geospatial Lake Erie, Lake Ontario
Online Only (Y/N) N
Additional Online Files (Y/N) N
Google Analytic Metrics Metrics page
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