Production of silica-saturated tholeiitic magmas in island arcs

Abstract

Experimental crystallization of synthetic silica-saturated tholeiite and basaltic andesite at high water pressures has indicated that magmas of these types may be produced by partial melting of hydrous mantle peridotite to maximum depths of 70 and 20 km respectively. These experiments lend little support to the suggestion that andesitic or dacitic magmas may originate by a similar process at depths as great as 100 km. An origin by partial melting of mantle peridotite which has gained water from the dehydration of downgoing oceanic crust is discussed for tholeiitic basalts and basaltic andesites in island arcs.