Mineral Dissolution in Silicate Melts

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

One of the fundamental questions for understanding volcanic and deep magmatic processes is how fast minerals grow or dissolve in a magma under a given condition. However, the seemingly simple question has only begun to be addressed recently. This award will allow the investigator to continue to undertake an experimental and theoretical modeling study of mineral dissolution and growth in silicate melts. Diffusive and convective crystal dissolution of plagioclase and quartz (two of the most major minerals) in magmas will be investigated in the next grant period. This study will provide predictive methods to calculate dissolution rates of specific minerals in silicate melts as a function of temperature, pressure and other conditions. Furthermore, the crystallization history of magma oceans during early evolution of Moon and Earth will be modeled. Mineral dissolution and growth are a fundamental process in igneous petrogenesis. In a magma conduit, chamber or ocean, entrained crystals and xenoliths 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 would undergo dissolution (if the ambient melt is undersaturated with respect to the mineral) or growth (if there is oversaturation) in the presence of convection. This study's ultimate aim is to provide a practical method for estimating convective mineral dissolution and growth rates. It is proposed to obtain the necessary data and develop relations to directly calculate diffusive and convective dissolution rates of two mafic minerals: olivine and clinopyroxene, in basaltic melts as a function of temperature, pressure, and melt composition. In this next grant period, the investigator and his team will investigate the dissolution kinetics of two felsic minerals: plagioclase in basaltic melts and quartz in felsic melts, including the relative role of interface reaction and mass transport in controlling the dissolution rates. Furthermore, with experimental data and theoretical understanding accumulated over the years, they will develop models for the crystallization history and evolution of lunar and terrestrial magma oceans. The new work will significantly improve our fundamental understanding of magmatic processes and magma ocean evolution.