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TitleInsights from combined interpretation of sediment cores and geophysical logs in the Niagara Peninsula, southern Ontario
DownloadDownload (whole publication)
AuthorBurt, A K; Crow, H
SourceRegional-Scale Groundwater Geoscience in Southern Ontario: An Ontario Geological Survey, Geological Survey of Canada, and Conservation Ontario Geoscientists Open House; by Russell, H A J; Ford, D; Holysh, S; Priebe, E H; Geological Survey of Canada, Open File 8528, 2019 p. 4, https://doi.org/10.4095/313544 (Open Access)
Year2019
Alt SeriesOntario Geological Survey, Open File Report 6349
PublisherNatural Resources Canada
PublisherGovernment of Ontario
MeetingRegional-Scale Groundwater Geoscience in Southern Ontario: Open House; Guelph; CA; February 27-28, 2019
Documentopen file
Lang.English
Mediaon-line; digital
RelatedThis publication is contained in Russell, H A J; Ford, D; Holysh, S; Priebe, E H; (2019). Regional-Scale Groundwater Geoscience in Southern Ontario: An Ontario Geological Survey, Geological Survey of Canada, and Conservation Ontario Geoscientists Open House, Geological Survey of Canada, Open File 8528
File formatpdf
ProvinceOntario
NTS30L/13; 30L/14; 30L/15; 30M/02; 30M/03; 30M/04; 30M/06
AreaNiagara Peninsula
Lat/Long WENS -80.0000 -78.7500 43.5833 42.7500
Subjectshydrogeology; surficial geology/geomorphology; environmental geology; geophysics; stratigraphy; geochemistry; sedimentology; sediments; core samples; geophysical logging; gamma ray logging; electromagnetic induction; conductivity; magnetic susceptibility; seismic velocities; temperature; geophysical interpretations; boreholes; lithology; groundwater resources; aquifers; geological mapping; 3-D mapping; source water protection; apparent conductivity; integrated approach; aquitards; Phanerozoic; Cenozoic; Quaternary
ProgramAquifer Assessment & support to mapping, Groundwater Geoscience
Released2019 02 08
AbstractIn 2013, the Ontario Geological Survey (OGS) initiated a three-dimensional (3-D) mapping project encompassing the Niagara Peninsula in support of source water protection and land use planning. Key project goals are to 1) build a regional scale 3-D framework model of Quaternary deposits that form both regional and local aquifers and aquitards, and 2) characterize the internal properties of the modeled units.
Between 2014 and 2017, 99 continuously cored boreholes were drilled, geologically logged, photographed and sampled in the field. Detailed sedimentological observations and field penetration test results on clay-rich intervals of core have now been augmented by pebble lithology counts and laboratory grain size and carbonate content analysis. Records were also kept regarding drilling methods, core recovery and intervals with drilling fluid losses.
The Geological Survey of Canada collaborated in the borehole study by acquiring a suite of geophysical logs in 14 boreholes which had been converted to PVC-cased monitoring wells. Natural gamma and induction (apparent conductivity and magnetic susceptibility) logs were acquired to investigate lithological variation within the sediments. Downhole seismic logs were acquired to measure material velocities. High-resolution fluid temperature logs identified regional groundwater temperature trends.
Significant changes in geophysical log responses were evident at major stratigraphic boundaries while subtle variations in responses provided insights into the geochemical and physical properties of the sediments within stratigraphic units. Key geological and geophysical logs from three boreholes have been selected to illustrate the benefits of an integrated approach. Borehole BH05 is characterised by glaciolacustrine mud and muddy diamicton, BH13 is dominated by glaciolacustrine mud, and BH14 intercepted gravel, sand and mud. Thinner beds of overconsolidated sandy silt diamicton and variably dolostone, gypsum and shale bedrock were also observed.
Gamma and induction responses are sensitive to changes in the proportion of sand, silt and clay within both diamicton and glaciolacustrine deposits. Potentially water-bearing sandy units are clearly distinguished by high magnetic susceptibility and low conductivity values while the reverse records units rich in clay-sized grains. On the Niagara Peninsula, it can be difficult to distinguish between glaciolacustrine mud and muddy till. However, decreases in velocity correspond to a change from grounded ice to a glaciolacustrine depositional setting, while increases in magnetic susceptibility relate to ice-rafted debris. The integrated examination of sediment cores and geophysical logs together provides an improved understanding of the complex local geological processes, and thus aided in the search for aquifers and the characterization of regional aquitard units.
GEOSCAN ID313544