Grant: Discovery Grants Program - Individual

The earth's crust is in a state of flux as the plates slowly move relative to one another.  They only move centimetres per year, but over geological time this adds up. For example, 1 cm/year is equivalent to 1,000 km in 100,000,000 years. This is a reasonable time-span for the development of a mountain chain by the collision of two plates. For a plate to move, its base and edges have to deform. Movement near the surface is accommodated by fracturing (faulting), which may result in earthquakes. At depth, due to pressure, it is accommodated  by ductile flow; the crystalline rock flows as a solid, without fracturing. The hotter the rock the faster it flows. The bending of a candle standing in the sun is a ductile process. The behaviour of glaciers is similar to that of rocks, they flow slowly as a solid at depth, and form faults (crevasses) near the surface. Also, their flow is considerably faster in warm southern Canada than in frigid Antarctica. I am interested in the mechanisms responsible for deformation at all scales, from plate to microscopic. The mechanisms are influenced by such factors as: rock properties, temperature, confining pressure, rate of deformation and boundary conditions (e.g. plates colliding, or moving apart). These factors determine the characteristics of the deformed rock, and by examining the characteristics, I reconstruct the deformation history. For example the fissility of slate is a product of the deformation history; a similar history at higher temperature produces a schist. My interest is in unraveling the deformation history of selected areas (currently in the Canadian Cordillera), in order to understand the general processes and  basic principles. My modus operandi involves field observation, theoretical considerations, numerical and physical experimentation, determination of past temperature and pressure, and dating of the various stages in the history. Work of this type is fundamental to understanding plate tectonics and related phenomena.