Melts of Ocean Island Basalts (OIB) and Their Sources: Evidence from Melt Inclusions and Quenched Glasses of Rocks

Abstract

In this paper, we examine the compositions of basaltic melts from ocean islands using our regularly updated database of analyses of melt inclusions in minerals and glasses of igneous rocks. Mean concentrations of major, trace, and volatile components in melts were calculated for the global dataset (22 550 analyses from 33 island systems) and for the most extensively studied complexes (Iceland, Hawaii, Canaries, Galapagos, and Reunion). It was found that the mean contents of most elements fall between the mean compositions of magmas from mid-ocean ridges (most depleted) and intraplate continental complexes (most enriched). Variations of element ratios in particular complexes were considered in detail, and it was found that they can be described by mixing magmas from a depleted source and variably enriched materials. The abundances of trace elements in the supposed mantle sources were estimated. The depleted source is most clearly manifested in Iceland and is almost identical to the depleted mantle the melting of which produces mid-ocean ridge basalts.