Conditions, rates and mechanisms of fundamental metamorphic processes

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The origin of rock texture and microstructure is one of the least understood aspects of metamorphic petrology. Yet it is known that it drastically influences some of the most elemental properties of Earth's crust such as its behavior during plastic deformation, the way it transmits seismic waves, or the rate with which thermal anomalies form and dissipate in response to tectonic processes. Funding is requested for research that will lead to a new level of understanding of the fundamental processes that govern the formation of rock texture and microstructure. This research will integrate detailed petrographic and geochronological investigations with equilibrium and kinetic modelling to quantify the rates and pressure, temperature and chemical conditions of these fundamental processes that include nucleation, crystal growth, diffusion and mineral dissolution.***In the past, an approach to chemical equilibrium was utilized to estimate the conditions of rock formation. However, recent research by the applicant and coworkers induced the question whether the disequilibrium required for rock-forming processes may be larger than previously assumed which would have important implications for the way rock-forming conditions are estimated and how these estimates are interpreted. A particular focus of the proposed research will be to quantify the departure from chemical equilibrium required for metamorphic processes, and how this depends on the interplay of interface and strain energy and directed stress and metamorphic mineral reaction kinetics. This research will help to evaluate and develop new constraints on important tectonic processes ranging from the nature and rates of mountain belt formation to the mechanisms of flow of semi-viscous rocks in Earth's mid-crust.***Major questions to be addressed by the research are: (1) What is the order of magnitude of the key parameters that impact on rock texture and microstructure formation? (2) How are these key parameters related to each other and how do they depend on changes of the metamorphic environment during geological processes? (3) What is the link between these parameters, rock microstructure, and large-scale tectonic processes? Research on the interplay and magnitudes of the key parameters for rock microstructure formation is still in its infancy but required to advance our understanding of the role of chemical reaction kinetics in geological systems. The proposed research will increase the competitiveness of Canada's earth science sector contributing to public's intrinsic interest in minerals and rocks and how they form. Direct applications of that research will provide links to the resource extraction industries which form an important segment of the Canadian economy.**