Kinetics of quenching of hydrous feldspathic melts: quantification using synthetic fluid inclusions

A microthermometric analysis of fluid inclusions preserved during the isobaric quenching of H₂O-saturated, vesicular silicate melts provides a method for the determination of the glass transition temperature of hydrous silicate melts at high pressure. The method is based on the principle that the contraction of inclusion cavities during quenching is rate-limited by the volume relaxation of the melt. Viscous relaxation of the melt ceases during cooling at the glass transition temperature. Bulk densities of the fluid inclusions whose volumes are frozen at the glass transition preserve a record of the trapping event, i.e., the glass transition temperature. The method has been applied to seven compositions on the join albite-orthoclase. -from Authors