Properties of Hydrous Haplogranitic Melts

Abstract

Water is generally recognized as the most important magmatic volatile component, both for its abundance and for its effects on physical and chemical properties of the melt. The fundamental role of water was understood very early by Goranson (1931), who emphasized that “many debatable problems of volcanology ... may be readily apparent if we know how water dissolved in magmas behaves at different temperatures and pressures”. The dramatic effects of the change of water content of the melt on phase relations (as outlined in Chap. 2) is due to the variation of physical properties of melts with changing water content (e.g., viscosity, density, diffusivity, solubility of other elements). Therefore, the role of water in melting processes (collecting and segregation of melts), migration of melts, and crystallization of magmas is fundamental.