| Title | Geology of the Aurora high-quality stratigraphic reference site and significance to the Yonge Street buried valley aquifer, Ontario |
| Download | Downloads |
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| Licence | Please note the adoption of the Open Government Licence - Canada
supersedes any previous licences. |
| Author | Sharpe, D R ;
Pullan, S E; Gorrell, G |
| Source | Geological Survey of Canada, Current Research (Online) no. 2011-1, 2011, 24 pages, https://doi.org/10.4095/286269  Open Access |
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| Year | 2011 |
| Publisher | Natural Resources Canada |
| Document | serial |
| Lang. | English |
| Media | on-line; digital |
| File format | pdf (Adobe Acrobat Reader) |
| Province | Ontario |
| NTS | 31D/03 |
| Area | Aurora; Whitby |
| Lat/Long WENS | -79.5000 -79.4167 44.0833 44.0000 |
| Subjects | hydrogeology; stratigraphy; aquifers; groundwater; groundwater resources; groundwater surveys; groundwater regimes; resource management; hydrostratigraphic units; lithostratigraphy; silts; clays; Aurora
Basin; Yonge Street aquifer; Whitby Shale; Thorncliffe Formation; Oak Ridges Moraine; Newmarket Till |
| Illustrations | location maps; photographs; profiles; stratigraphic columns; block diagrams |
| Program | Groundwater Geoscience Aquifer Assessment &
support to mapping |
| Released | 2011 06 07 |
| Abstract | The Geological Survey of Canada (GSC) Aurora cored borehole intersects the Yonge Street aquifer (YSA), an important groundwater source in Ontario. The borehole, sited along a 7 km long seismic profile,
was drilled in order to provide data to improve sustainable use and management of groundwater in Aurora well fields and the regional aquifer system. Results provide high-quality hydrostratigraphic reference data, geological context, and a prospecting
model for this significant buried-valley aquifer. The improved conceptual hydrogeological model offers a plan to effectively stress and assess the YSA system.
A 130 m sedimentary succession unconformably overlies subhorizontal Whitby shale and a
low-relief bedrock surface with no defined valleys. Gas seeping from the shale is trapped in Thorncliffe Formation, a regional aquifer below confining aquitards. The regional aquifer occurs below ~209 m a.s.l. and is a 80 m thick, fining-upward, sand
and gravel sequence. It appears to represent a portion of a northeast-southwest-oriented channel, esker, and subaqueous fan system that fed Thorncliffe Formation aquifer sediments to the south. The newly identified aquifer system occurs above a
regional unconformity within the succession. A 25 m thick Newmarket Till and silt-clay rhythmite sequence confines this aquifer. This aquitard drapes into Aurora basin, a possible pre-existing sediment valley. High clay content in aquitard rhythmites
may allow conductivity logs to map it as a marker horizon. The overlying Oak Ridges Moraine (ORM) aquifer occurs as a 30 m thick gravel-sand-mud sequence above a second regional unconformity within the succession. This channel fill sequence is
thinner than nearby 100 m thick ORM channel sediments. |
| GEOSCAN ID | 286269 |
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