Oxygen isotope evidence for slab-derived silicate melt in Lau basin back-arc lavas

Abstract

Geochemical variations in back-arc basin lavas have been attributed to varying proportions of compositionally distinct mantle and slab-derived components in their sources. Possible slab components (fluids, melts, or rocks from sedimentary, mafic or ultramafic parts of the lithosphere) are heterogeneous in oxygen-isotope compositions (δ^(18)O). Consequently, δ^(18)O values of back-arc lavas can provide information on the origin (e.g., the part of the slab from which they were derived), amounts, and properties (fluids vs. melts) of slab components delivered to the back-arc mantle.

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