PRIMITIVE MANTLE MAGMAS RECORDED AS SILICATE MELT INCLUSIONS IN IGNEOUS MINERALS

Abstract

This paper reviews work on primitive silicate melt inclusions in basalt phenocrysts and evaluates its significance. Primary melt inclusions are small quantities of silicate melt included in minerals during coarsening, growth or recrystallisation of the crystal structure. Because they contain liquids formed in thermodynamic equilibrium with their host minerals, primary melt inclusions produced at different stages of evolution of the melts will record the liquid line of descent of magmatic systems. Moreover, assuming they become closed to the surrounding systems since the time of entrapment, primary melt inclusions in early-formed crystals may isolate pristine samples of high-pressure mantle-derived melts that were trapped prior to mixing at shallower levels. They can thus be used to obtain information on the processes that create magmas and the nature of their mantle source regions.