Abstracts

233 - Using geophysical logs for stratigraphic assessment of
glaciated terrains in southern Ontario
Heather Crow, Susan Pullan, & Hazen Russell
Geological Survey of Canada, Ottawa, Ontario, Canada
Downhole geophysical logs provide a means of identifying stratigraphic changes and characterizing
lithological units based on variations in physical properties of sediments. A suite
of logs, including natural and active spectral gamma, induced conductivity and magnetic
susceptibility, fluid temperature, and P and S-wave velocities, has been collected by the
Geological Survey of Canada in 55 wells drilled in glaciated terrains of southern Ontario.
This dataset provides the most comprehensive downhole geophysical characterization
available of Late Wisconsin stratigraphy in the province Ontario.
The wells are located within the Oak Ridges, Oro, and Waterloo moraines, and boreholes
range in depth from 25 – 200 m. The Quaternary stratigraphy consists of a succession of
sedimentary units separated by distinct erosional surfaces that can have considerable relief
due to incision by paleo-valleys. The geophysical data thus provides characterization of a
range of glacial and proglacial sedimentary settings that consist of laminated muds, sand
and gravel, and mud and sandy diamictons.
The geophysical signatures are varied, but common patterns emerge in the log suites
which can be attributed to certain glacial facies. For example, saw tooth patterns in
the gamma and induction logs indicate sediment dominated by high-energy environments
and rapid deposition. Hour glass and reverse hour-glass signatures are seen in
lower energy, rhythmically stratified mud and fine sand. Elevated P-wave velocities in
a stratigraphically young diamicton overlying lower velocity diamictons are indicative
of the Newmarket Till.
POSTER SESSION: Sustainability of
Groundwater Resources
Thursday October 29, 16:40
Room: Regent
118 - Groundwater Supplies from the Pierson Channel Buried
Valley Aquifer
Jeffery J. Bell
Friesen Drillers Ltd., Steinbach, Manitoba, Canada
A buried valley aquifer lies in the far southwestern corner of the Province of Manitoba,
which is known as the Pierson Channel Buried Valley Aquifer. The bedrock geology in
the area is the Pierre Formation, which consists of green bentonitic shale. During bedrock
surface mapping by the GSC in 1970, the buried valley feature was mapped, and
the thelweg of the channel was approximately determined. The entire sequence of the
180 IAH-CNC 2015 WATERLOO CONFERENCE