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TitleGeochemistry of southern Ontario Quaternary sediments
DownloadDownload (whole publication)
AuthorKnight, R D; Bajc, A F; Kjarsgaard, B A; Crow, H; Stepner, D A J; Sharpe, D R; Russell, H A J
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. 18, (Open Access)
Alt SeriesOntario Geological Survey, Open File Report 6349
PublisherNatural Resources Canada
MeetingRegional-Scale Groundwater Geoscience in Southern Ontario: Open House; Guelph; CA; February 27-28, 2019
Documentopen file
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
NTS30; 31B; 31C; 31D; 31E; 31G; 40; 41A; 41G; 41H/03; 41H/04; 41H/05; 41H/06; 41H/12; 41H/13
AreaSouthern Ontario; Great Lakes
Lat/Long WENS -84.0000 -74.0000 46.0000 41.5000
Subjectshydrogeology; geochemistry; stratigraphy; Health and Safety; groundwater; aquifers; sediment geochemistry; boreholes; core samples; x-ray fluorescence analyses; mass spectrometer analysis; provenance; bedrock geology; lithology; sedimentary rocks; carbonates; dolomites; limestones; calcium geochemistry; magnesium geochemistry; glacial deposits; tills; Newmarket Till; Catfish Creek Till; chemostratigraphy; provenance indicators; human health; Phanerozoic; Cenozoic; Quaternary; Paleozoic; Precambrian
ProgramAquifer Assessment & support to mapping, Groundwater Geoscience
Released2019 02 08
AbstractGeochemical analysis constrained by stratigraphic units with detailed sampling of continuous core is rare in glaciated basins. The up to 200 m plus thickness of surficial sediment cover across 74,000 km2 area of southern Ontario (S-ON) and the presence of many hundred continuously cored boreholes provided an opportunity to investigate the chemostratigraphy of a large glaciated basin. The S-ON basin setting over Phanerozoic sedimentary carbonate and shale, and bounded by igneous and metamorphic rocks of Canadian Shield, provides an ideal setting for geochemical provenance studies and methods development. Geochemical analysis of 3,815 surficial sediment samples from 53 boreholes have been analysed via portable X-ray fluorescence spectrometry (pXRF) and traditional laboratory geochemical analytical methods.
Comparison of geochemistry from ICP-ES/MS and with pXRF indicates good characterization of the basin chemistry by the laboratory and pXRF analysis methods. Significant changes in elemental concentrations within individual cores are identified in multiple contexts, i) across formation contacts, ii) internally within formations, iii) absence of change across formation boundaries. These likely represent changes in depositional processes and provenance between Precambrian Shield and Paleozoic sources. Changes in elemental concentrations are commonly not correlated between boreholes at either the formation or sub formation level. On a regional scale, the geochemical ratio of CaO+MgO/SiO2+Al2O3 provides a Provenance Indicator (PI) to determine elemental contributions from a Paleozoic carbonate source relative to contributions from Precambrian Shield sources. As calcium and magnesium occurs in markedly higher concentrations in Paleozoic carbonate rocks, a higher PI value reflects greater input of material derived from these Paleozoic sedimentary rocks. Examination of the Newmarket Till using this PI shows a correlation between the amount of carbonate-derived material in the till-matrix and sampling distance relative to the shield margin indicates the deposition of increasingly carbonate-rich surficial sediments to a maximum at approximately 80-100 km south of the Shield-margin. Additionally to the PI, a geochemical distinction is observed between sediments deposited east (carbonate dominated) and west (dolomite dominated) of the Niagara Escarpment. Elevated MgO and CaO west of the Niagara Escarpment (Catfish Creek Till) indicates sourcing of Silurian dolomite, whereas east of the Escarpment (Newmarket Till) CaO-rich till is due to sourcing of Ordovician limestone.
The geochemical study of Quaternary sediments in southern Ontario has not found any evidence of elemental concentrations that might adversely affect groundwater quality and human health.