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Lobal affinity of late Wisconsin tills at St. Marys in southwestern Ontario, Canada

Aleksis Dreimanis, Paul F. Karrow and Peter J. Barnett
Lobal affinity of late Wisconsin tills at St. Marys in southwestern Ontario, Canada
Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre (September 2014) 51 (9): 837-849

Abstract

The exposures at the St. Marys Cement Inc. quarry at St. Marys, Ontario, have been studied by geologists since the mid-1950s. This paper summarizes previous and new information collected in 2009, 2010, and 2012 and discusses the record of sediments resting on the bedrock surface that have been exposed during quarry operations. The exposed sediments illustrate the dynamic behavior of the Laurentide Ice Sheet in this area during the Late Wisconsin. Evidence for subglacial meltwater activity, shifting ice-flow directions during till deposition, a local or regional erosion event, possible subaerial exposure, and ice-marginal sedimentation is observed in the sequence of tills and stratified sediments exposed in the quarries. It also highlights how rapid lateral facies changes, complex contact relationships, and steep erosional contacts can prove to be challenging for correlation and extrapolation of subsurface units into three-dimensional stratigraphic models. Fourteen units were identified of which the lower six were deposited during the Nissouri age (Catfish Creek Drift). This included five layers of till deposited by a glacier that alternated from flowing out of the Lake Huron basin to that of a regional flow to the south-southwest. An angular unconformity cuts into these sediments and separates them from a finer-grained sediment sequence (primarily of Port Bruce age) consisting of glaciofluvial gravel, two fine-textured till layers, and rhythmically bedded glaciolacustrine sediments, all overlain by the uppermost till, the Rannoch Till, and Mitchell Moraine ice-marginal fan sediments.


ISSN: 0008-4077
EISSN: 1480-3313
Coden: CJESAP
Serial Title: Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre
Serial Volume: 51
Serial Issue: 9
Title: Lobal affinity of late Wisconsin tills at St. Marys in southwestern Ontario, Canada
Affiliation: University of Western Ontario, Department of Earth Sciences, London, ON, Canada
Pages: 837-849
Published: 201409
Text Language: English
Summary Language: French
Publisher: National Research Council of Canada, Ottawa, ON, Canada
References: 27
Accession Number: 2014-085351
Categories: Quaternary geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sect., 3 tables, geol. sketch maps
N43°16'00" - N43°16'00", W81°07'60" - W81°07'60"
Secondary Affiliation: University of Waterloo, CAN, CanadaOntario Geological Survey, CAN, Canada
Country of Publication: Canada
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Canadian Science Publishing, NRC Research Press, Ottawa, ON, Canada. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201444
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