Deep structure beneath Lake Ontario: Crustal-scale Grenville subdivisions

Canadian Journal of Earth Sciences
By: , and 

Links

Abstract

Lake Ontario marine seismic data reveal major Grenville crustal subdivisions beneath central and southern Lake Ontario separated by interpreted shear zones that extend to the lower crust. A shear zone bounded transition between the Elzevir and Frontenac terranes exposed north of Lake Ontario is linked to a seismically defined shear zone beneath central Lake Ontario by prominent aeromagnetic and gravity anomalies, easterly dipping wide-angle reflections, and fractures in Paleozoic strata. We suggest the central Lake Ontario zone represents crustal-scale deformation along an Elzevir–Frontenac boundary zone that extends from outcrop to the south shore of Lake Ontario.Seismic images from Lake Ontario and the exposed western Central Metasedimentary Belt are dominated by crustal-scale shear zones and reflection geometries featuring arcuate reflections truncated at their bases by apparent east-dipping linear reflections. The images show that zones analogous to the interpreted Grenville Front Tectonic Zone are also present within the Central Metasedimentary Belt and support models of northwest-directed crustal shortening for Grenvillian deep crustal deformation beneath most of southeastern Ontario.A Precambrian basement high, the Iroquoian high, is defined by a thinning of generally horizontal Paleozoic strata over a crestal area above the basement shear zone beneath central Lake Ontario. The Iroquoian high helps explain the peninsular extension into Lake Ontario forming Prince Edward County, the occurrence of Precambrian inlier outcrops in Prince Edward County, and Paleozoic fractures forming the Clarendon–Linden structure in New York.

Study Area

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Deep structure beneath Lake Ontario: Crustal-scale Grenville subdivisions
Series title Canadian Journal of Earth Sciences
DOI 10.1139/e94-025
Volume 31
Issue 2
Year Published 1994
Language English
Publisher NRC Research Press
Contributing office(s) Woods Hole Coastal and Marine Science Center, Coastal and Marine Geology Program
Description 16 p.
First page 255
Last page 270
Country Canada, United States
Other Geospatial Lake Ontario
Online Only (Y/N) N
Additional Online Files (Y/N) N