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Conceptual hydrogeological model of the Yonge Street Aquifer, south-central Ontario; a glaciofluvial channel-fan setting

Richard E. Gerber, David R. Sharpe, Hazen A. J. Russell, Steve Holysh and Esmaeil Khazaei
Conceptual hydrogeological model of the Yonge Street Aquifer, south-central Ontario; a glaciofluvial channel-fan setting (in Quaternary geology of southern Ontario and applications to hydrogeology, Hazen A. J. Russell (editor), Emmanuelle Arnaud (editor), Andrew F. Bajc (editor) and David R. Sharpe (editor))
Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre (July 2018) 55 (7): 730-767

Abstract

The Yonge Street Aquifer (YSA) in the Greater Toronto Area of south-central Ontario is a prolific municipal supply aquifer. It has been considered to be channelized sand and gravel linked to a bedrock valley. Despite considerable work, the fundamental conceptual model for the YSA is not well developed and documented. Based on high-quality data, a revised conceptual model of the aquifer is presented. Seismic profiles define the geometry of the regional stratigraphy with four distinct units: bedrock, Lower sediments, Newmarket Till, and Oak Ridges Moraine (ORM) sediment. Seismic data reveal two generations of roughly north-south channels: older sub-Newmarket Till channels within Lower sediments (termed Thorncliffe channel) and ORM-related channels (termed ORM channel) that incise both Newmarket Till and Lower sediments. The YSA is interpreted to occur within a Thorncliffe channel, with possible vertical connection to younger ORM channels and lateral connection to inter-channel Lower sediments. Thorncliffe channel deposits consist of fining-upward transitions from coarse gravel, to sand, to rhythmically bedded mud interpreted to be deposited within a channel - esker - subaqueous fan complex. Upper Thorncliffe channel mud facies and overlying Newmarket Till provide a capping aquitard. The YSA conceptual model benefits from a strong understanding of facies changes in the Thorncliffe Formation. The deposits with highest permeability occur within up to 80 m thick gravel and sand sequences at the base of the Thorncliffe channel, with transmissivity ranging from 1500 to 4500 m (super 2) /day. Groundwater level response to municipal pumping confirms connection along the channel with muted hydraulic response laterally. Thorncliffe channels are interpreted to be up to 20 km long and approximately 2 km wide.


ISSN: 0008-4077
EISSN: 1480-3313
Coden: CJESAP
Serial Title: Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre
Serial Volume: 55
Serial Issue: 7
Title: Conceptual hydrogeological model of the Yonge Street Aquifer, south-central Ontario; a glaciofluvial channel-fan setting
Title: Quaternary geology of southern Ontario and applications to hydrogeology
Author(s): Gerber, Richard E.Sharpe, David R.Russell, Hazen A. J.Holysh, SteveKhazaei, Esmaeil
Author(s): Russell, Hazen A. J.editor
Author(s): Arnaud, Emmanuelleeditor
Author(s): Bajc, Andrew F.editor
Author(s): Sharpe, David R.editor
Affiliation: Oak Ridges Moraine Groundwater Program, Toronto, ON, Canada
Affiliation: Canadian Geological Survey, Ottawa, ON, Canada
Pages: 730-767
Published: 201807
Text Language: English
Summary Language: French
Publisher: National Research Council of Canada, Ottawa, ON, Canada
References: 128
Accession Number: 2018-082144
Categories: HydrogeologyApplied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. block diag., sects., strat. cols., 6 tables, geol. sketch maps
N43°45'00" - N44°15'00", W79°45'00" - W79°15'00"
Secondary Affiliation: Canadian Geological Survey, CAN, CanadaToronto and Region Conservation Authority, CAN, Canada
Country of Publication: Canada
Secondary Affiliation: GeoRef, Copyright 2018, 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: 2018
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