Intellectual merit. This proposal will investigate diffusive crystal dissolution in silicate melts ? one of the key processes in igneous petrogenesis. In a magma conduit, chamber or ocean, entrained xenoliths/xenocrysts and newly crystallized minerals would sink or rise depending on their density relative to the melt. The relative motion induces convection. Upon descent or ascent, each mineral grain could undergo dissolution in the presence of convection. The convective dissolution rate of minerals in silicate melts has not been quantified before. Recent theory can predict convective dissolution rates; the necessary input parameters include the system conditions (melt and mineral compositions as well as temperature and pressure), melt and mineral density, the solubility of the mineral, diffusivity of the principal equilibrium-determining component, and viscosity of the melt. This project is designed to constrain these parameters. Viscosity and density can be estimated from available models. The diffusivity and solubility may be extracted from diffusive dissolution experiments. New work is proposed work as follows: (i) testing the theory for applicability in magmatic systems; (ii) conducting diffusive crystal dissolution experiments, from which diffusivity and solubility will be extracted; (iii) quantifying data from diffusive crystal dissolution experiments as a function of temperature and pressure; (iv) developing models to predict diffusive and convective crystal dissolution rates in nature, focusing on convective dissolution rates as a function of temperature and pressure for a given mineral-melt system. The ultimate goal is to develop a tool to predict convective dissolution rate of crystals in natural silicate melts, with application to digestion or survival of xenocrysts in magmas.
Broader Impacts. The project will support graduate and undergraduate students, a post-doctoral research associate. Participation of an international collaborator will further scientific networking between the United States and other nations. The P.I. regularly incorporates his research into teaching at different levels.
