|Title||Insights from combined interpretation of sediment cores and geophysical logs in the Niagara Peninsula, southern Ontario|
|Download||Download (whole publication) |
|Licence||Please note the adoption of the Open Government Licence - Canada
supersedes any previous licences.|
|Author||Burt, A K; Crow, H|
|Source||Regional-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
|Alt Series||Ontario Geological Survey, Open File Report 6349|
|Publisher||Natural Resources Canada|
|Publisher||Government of Ontario|
|Meeting||Regional-Scale Groundwater Geoscience in Southern Ontario: Open House; Guelph; CA; February 27-28, 2019|
|Related||This publication is contained in Regional-Scale Groundwater
Geoscience in Southern Ontario: An Ontario Geological Survey, Geological Survey of Canada, and Conservation Ontario Geoscientists Open House |
|NTS||30L/13; 30L/14; 30L/15; 30M/02; 30M/03; 30M/04; 30M/06|
|Lat/Long WENS|| -80.0000 -78.7500 43.5833 42.7500|
|Subjects||hydrogeology; 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; Phanerozoic; Cenozoic; Quaternary|
|Program||Groundwater Geoscience Aquifer Assessment & support to mapping|
|Released||2019 02 08|
|Abstract||In 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.
|Summary||(Plain Language Summary, not published)|
Volume of abstracts for Ontario Geological Survey and Geological Survey of Canada groundwater geoscience Open house with Conservation Ontario.