Electromagnetic imaging of lithospheric and environmental targets

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Electromagnetic (EM) imaging provides information critical for answering questions from the very large-scale, such as how North America has formed and been deformed over the last 3 billion years, to the small-scale, such as how CO2 gas is distributed in the shallow sub-surface. EM studies involve recording and analyzing signals produced in the Earth by sources in the ionosphere and atmosphere and artificial sources including energized coils and wires. Signals with different frequencies and sources penetrate to different depths enabling imaging over multiple scales. The proposed research will address questions at the interface of geophysics and geology, examining parameters controlling electrical conductivity, and extracting information on tectonic, geological, and environmental processes. It will include training of a visiting scholar and at least one Ph.D., two M.Sc., and two B.Sc. (Honours) students, providing them with high-level knowledge and skills critical in tectonic studies, resource exploration, sustainable development, and environmental monitoring. ******The first component of the research will use the deep-penetrating magnetotelluric (MT) method to study continental crust and lithosphere in the Superior Province, Hudson Bay Basin, and northern Canadian Cordillera. Objectives include mapping lithospheric thickness, delineating conductive zones that trace fluid transport and crustal sutures, and defining anisotropic (directionally-varying) resistivity. This work will provide new information on tectonic processes and smaller-scale geological structures. In addition to improving the accuracy of MT interpretations and adding substantial value to existing national data sets, the results will provide important information for exploration for hydrocarbon, diamond, and mineral deposits. ******The second component of the research is EM imaging of CO2 injection at the Aquistore site at Estevan, Saskatchewan. Aquistore is being used to investigate the sequestering of CO2 in deep sedimentary basins as a method of greenhouse gas reduction and is one of a small number of such study sites globally. The project involves application of fairly well established EM methods to a new target, a 3.4 km deep CO2 reservoir unit located in the vicinity of a power station. Over the last four years we have collected a large data base of MT and controlled-source EM (CSEM) data at the site. The proposed research involves fully characterizing the CSEM data, including the repeatability of the measured responses, and determination of the pre-injection resistivity structure between the reservoir zone and the surface. The project will provide an internationally-important evaluation of the capacity of surface EM methods for monitoring CO2 sequestration in deep continental reservoirs and has significance for long-term reduction in greenhouse gases using sequestration methods.