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TitleRegional unconformities and the sedimentary architecture of the Oak Ridges Moraine area, southern Ontario
LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorSharpe, D; Pugin, A; Pullan, S; Shaw, J
SourceCanadian Journal of Earth Sciences vol. 41, no. 2, 2004 p. 183-198, Open Access logo Open Access
Alt SeriesGeological Survey of Canada, Contribution Series 200030
Alt SeriesEarth Sciences Sector, General Information Product 13
PublisherCanadian Science Publishing
Mediapaper; on-line; digital
File formatpdf
NTS30M/13; 30M/14; 30M/15; 30M/16NW; 30M/16NE; 31C/04SW; 31C/04NW; 31D/01; 31D/02; 31D/03; 31D/04
AreaToronto; Newmarket; Trenton; Whitby; Port Hope; Aurora; Finger lakes; Canada; United States of America
Lat/Long WENS-80.0000 -77.7500 44.2500 43.7500
Lat/Long WENS-77.5000 -76.0000 43.2500 42.5000
Subjectssurficial geology/geomorphology; stratigraphy; geophysics; glacial deposits; moraines; drumlins; depositional history; channel deposits; sedimentation; seismic reflection surveys; seismic surveys; stratigraphic analyses; lithostratigraphy; unconformities; erosion; Oak Ridges Moraine; Late Wisconsinan Unconformity; seismic facies; Cenozoic; Quaternary
Illustrationssketch maps; block diagrams; digital elevation models; cross-sections; seismic profiles; photographs
ProgramNSERC Natural Sciences and Engineering Research Council of Canada
ProgramOak Ridges Moraine NATMAP Project
AbstractSeismic stratigraphy, geometry, and sediment facies within the Oak Ridges Moraine (ORM) area of Ontario record major structural elements and surfaces of the Quaternary sedimentary sequence. The derived stratigraphic architecture can be used to identify the key elements of a regional erosional surface, represented by an unconformity in the subsurface, and associated overlying channel sediments. The erosional surface - unconformity forms a distinct time datum in the Quaternary sequence, which provides an important aid to lithostratigraphic correlation. The architecture also gives improved understanding of the effects of erosion on the late-glacial landscape. The surfaces of erosional drumlins and intervening troughs, and the beds and banks of meltwater channels in the ORM area, define the regional unconformity, highlighted by seismic profiles linked to continuously cored boreholes. These features are attributed to regional-scale, subglacial meltwater flow events. The sculpted surfaces, which are analogous to water-eroded forms, the presence of boulder lags and coarse-grained deposits on the regional erosional surface, and the channels with undulating profiles provide the vital supporting evidence for a meltwater interpretation. The inter-regional extent of the unconformity is inferred from the coherence of regional paleoflows and the extent of drumlinized uplands, tunnel channels, and scoured bedrock terrain across ~75% of the landscape from the ORM area east and south to the Finger Lakes, New York. The implied magnitude of erosion suggests a pressing need for directed sedimentological study in those ocean basins that were probable depositional sites for flood deposits.

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