Fundamental rock magnetic studies on single-domain particles and anisotropy, and applications to paleomagnetism and petrophysics

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This program will study some fundamental aspects of rock magnetism, and its application to paleomagnetism and petrophysics. Important information concerning the intensity and direction of the ancient magnetic fields (paleomagnetism) of the Earth, Moon, rocky planets and meteorites in the geological past is carried by small stable single-domain (SSD) magnetic particles in rocks. The magnetic information they carry is locked-in when the rock is formed (called a natural remanent magnetization, NRM), and can remain stable over millions of years. This information is crucial for understanding the magnetic history of rocky planetary bodies, and for providing the data for reconstructing past plate tectonic motions on the Earth. This program will study some fundamental properties of SSD particles. One of the main aims is to improve computations of the ancient field direction and intensity from anisotropic rocks (rocks whose properties vary in different directions), which would enable useful paleomagnetic data to be obtained from a wider range of samples than has hitherto been possible. This could include older samples that are often more anisotropic and where reliable paleomagnetic data may not previously have been generated. This in turn could potentially allow plate tectonic reconstructions to be made further back in time. Another key aspect will be studying the properties of particles slightly larger than SSD size, and quantifying the conditions under which these particles can transform into metastable single-domain states. This is important since it may help to explain why a significant fraction of the NRM in rocks appears to reside in these slightly larger particles.*******The program will also study the fundamental properties of smaller single-domain particles that are termed superparamagnetic (SP). Whilst these particles do not retain a remanent magnetization, and are therefore not important in terms of paleomagnetism, we are pioneering their use as nanoparticle contrast agents. Their high magnetic susceptibility and small size makes them ideal tracers for monitoring the progress and environmental effects of hydraulic fracturing operations, monitoring production processes in the oil sands, and other applications important to the Canadian economy.*******Another aim of the program is to further establish links between rock magnetism and petrophysical parameters. In particular, we aim to quantify the relationships between magnetic anisotropy and the anisotropies of other key petrophysical properties (such as fluid permeability anisotropy, acoustic anisotropy, electrical anisotropy). This potentially will provide a means of estimating these other petrophysical properties from rapid, non-destructive magnetic anisotropy techniques. This would have important applications for optimizing production in shale oil and gas plays, and other types of reservoir where anisotropy is a key factor.***