Kinetics of garnet nucleation and growth during metamorphism

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The proposed research aims at a quantitative understanding of two fundamental processes during rock formation: nucleation and crystal growth. The rates and mechanisms of these processes will be investigated and their influences on the size and spatial distribution and chemical composition of the mineral content of rocks will be studied. The sizes and shapes of all the mineral grains in a rock and their mutual interrelationships define the texture of the rock. My research will provide new insights into the nature and rates of texture formation. This is important since rock-texture fundamentally contributes to bulk rock properties such as electrical conductivity, strength and the way solid Earth responds to changes in external forces. Only little is known about the mechanisms that control rock-texture formation and novel findings are required. A major focus of my research will be on the crystallization of garnet during rock metamorphism. Garnet is chosen because its chemical composition reflects the pressure (P) and temperature (T) conditions that prevailed in the Earth's crust during crystallization. It also allows for the determination of the rates with which P and T changed through time. This information is fundamental for an understanding of the tectonic evolution of mountain belts. Numerical models that simulate garnet crystallization will be developed and calibrated with mineral chemistries and textures observed in rocks. Progress will be made on the quantification of the rates of chemical equilibration during metamorphism. This is needed to correctly interpret mineral zoning and mineral assemblages on which so much tectonic interpretation depends. Funds are requested for field work, related costs for analytical studies and for the support of graduate and undergraduate students. Mentoring and training of students is an essential target of this research. Besides a deep understanding of fundamental processes during rock evolution, students will gain experience in the development of a research program, the communication of research results, and the application of state-of-the-art analytical and computational techniques.