The proposed research will elucidate the relationship between density and coordination changes of Al3+, Fe3+ and Ti4+ in silicate melts. Experiments are designed to obtain precise measurements of melt density using the double-bob Archimedean method over a range of compositions and temperatures at a pressure of one bar. The proposed density measurements will complement information on melt structure obtained by NMR, Raman and IR spectroscopy. Properties such as density, and the factors that affect them, are fundamental in studies of magma evolution - - they affect melt segregration at the source region, magma ascent through diapirs and fractures, and the processes that produce chemical diversification in magmas.
