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Geophysical Research at the University of Manitoba, Department of Geological Sciences

The geophysics research group at the University of Manitoba consists of three faculty members: Dr. Ian Ferguson (Professor), Dr. Andrew Frederiksen (Associate Professor), and Dr. Wooil Moon (Professor Emeritus), along with one technician and a variable number of graduate students (four as of July, 2014).

The research of Ian Ferguson and students in the electromagnetic geophysics group includes magnetotelluric (MT) imaging and tectonic interpretation of Precambrian continental lithosphere; examination of the effects of Earth resistivity on electrical power transmission; and application of electromagnetic (EM) methods in near-surface environmental and groundwater studies. The MT studies focus on Precambrian terrains in Canada and Australia, and have included studies of the Trans Hudson Orogen; Grenville Province; Western Superior province; Slave craton, Wopmay orogen and Canadian Cordillera; and Yilgarn craton and Fraser orogen in Australia. In the most recent study Ferguson and students have imaged the crust and lithospheric mantle beneath the Grenville Province in southern Ontario (Figure 1). The primary objective of the recent work in power transmission studies has been examination of the control of geological structures on ground potential rise of HVDC electrodes, e.g., the effect of the anisotropy in layered rocks in sedimentary basins. Previous near-surface studies of the electromagnetic geophysics group have included mapping paleochannel aquifers in southwestern Manitoba; delineating saltwater contamination in oil-fields in southwestern Manitoba; investigating shallow fracturing and groundwater in Precambrian shield rocks; monitoring freezing of soil; and delineating thickness and pore-water salinity of mine tailings (Figure 2). He is presently working on projects involving EM monitoring of CO2 sequestration at the Aquistore site in Saskatchewan and delineating permafrost at an anthropological site in the Canadian Arctic.

Fig. 01
Figure 1. Crustal resistivity overlain by seismic reflection profiles (Adetunji et al. 2014). Black continuous lines show previous interpretation based on seismic results and the dashed lines show additions and modifications of the interpretation based on resistivity data. GF=Grenville Front, CMMBz=Central Metasedimentary Boundary Belt Zone.
Fig. 02
Figure 2. Correlation of EM measurements and acid mine drainage at the Central Manitoba tailings (Sherriff et al. 2009). Image shows the EM31 horizontal-dipole mode apparent conductivity response draped over and blended with the relative elevation changes. Labelled values correspond to the pH measured in near-surface samples at these approximate locations. Red fenced lines labelled X-X’, Y-Y’, and Z-Z’ indicate locations of EM31 and EM38 profiles used for full 2-D inversion.

Andrew Frederiksen is a specialist in earthquake seismology, working on determining the structure of continental lithosphere from recordings of earthquake data, and so contributing to understanding the tectonic history of the Canadian Shield and the differing dynamics of the crustal and lithospheric processes involved. Figure 3 shows an example of his ongoing work in central Canada and adjacent areas of the United States, using two teleseismic methods (teleseismic tomography, which is sensitive to temperature and bulk composition, and shear-wave splitting, which is sensitive to mantle fabric) to map domains within the lithosphere of the Canadian shield, which are then related to tectonic and convective events over the past 2.6 Ga (Superior accretion, the Trans-Hudson orogeny, extension along the Mid-Continent Rift, and the influence of the Great Meteor hotspot). Continuing work on this area is being done as part of the international/multi-institution SPREE (Superior Province Rifting Earthscope Experiment, Stein et al., 2011) project, in which instrumentation was installed along the Mid-Continent Rift axis in both Canada and the USA from 2011-2013. Dr. Frederiksen is also currently developing improved techniques for extracting structural information from teleseismic data, such as a newly-developed method for independently measuring crustal thickness, sedimentary basin thickness, and crustal P/S velocity ratio from teleseismic P waves.

Wooil Moon is retired, but remains an active researcher in the areas of satellite geophysics and remote sensing.

Fig. 03
Figure 3. Comparison of seismic velocities obtained by P-wave tomography (red/blue shading) at two depths (150 km, left; 250 km, right) with shear-wave splitting measurements (green arrows and black contours, left panel) at sites in the western Superior Province, Mid-Continent Rift, and adjacent areas. A possible interpretation is overlain on the right panel (Frederiksen et al., 2013).

Contact information

Department of Geological Sciences
University of Manitoba
125 Dysart Road, Winnipeg, MB, R3T 2N2

I. Ferguson: IJ.Ferguson@umanitoba.ca, 204-474-9164
A.W. Frederiksen: Andrew.Frederiksen@umanitoba.ca, 204-474-9460
W. Moon: Wooil.Moon@umanitoba.ca, 204-474-9833

End

About the Author(s)

Ian Ferguson received his received his B.Sc. in 1981 and his Ph.D. in 1988 from Australian National University. He came to Canada in 1988 to take up a postdoctoral fellowship at the University of Toronto and has been on faculty at the University of Manitoba since 1990, currently at the rank of Professor. From 2009 to 2014 he was also Head of the Department of Geological Sciences. His research is focused on understanding the electrical conductivity of the earth at scales ranging from the near-surface to the deep lithosphere, primarily using electromagnetic and magnetotelluric techniques, and using conductivity to obtain information about lithology, mineralogy, pore fluids and tectonic history. He also does research and consulting work involving geomagnetically-induced currents, which are a potential hazard to powerline and pipeline infrastructure.

References

Adetunji A., Ferguson, I.J., and Jones, A.G., 2014. Crustal and lithospheric scale structures of the Precambrian Superior-Grenville margin. Tectonophysics, 614, 146–169.

Frederiksen, A.W., Bollmann, T., Darbyshire, F., and van der Lee, S., 2013, Modification of continental lithosphere by tectonic processes: A tomographic image of central North America, J. Geophys. Res. Solid Earth, 118, 1051–1066, doi:10.1002/jgrb.50060.

Sherriff, B.L., Ferguson, I.J, Gupton, M.W., VanGulck, J.F., Sidenko, N., Priscu, C., Pérez- Flores, M., Gómez-Treviño, E., 2009. A geophysical and geotechnical study to determine the hydrological regime of the Central Manitoba Gold Mine Tailings Deposit. Can. Geotech. J., 46, 1, 69-80.

Stein, S., et al., 2011. Learning from failure: The SPREE Mid-Continent Rift experiment, GSA Today, 21, 5–7, doi:10.1130/G120A.1.

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