Trace element fractionation processes in the generation of island arc basalts

Abstract

Subduction-related magmas are characterized by distinctive minor and trace element ratios which are widely attributed to the introduction of a hydrous component from the subducted crust. Island arc rocks may usefully be subdivided into high and low Ce/Yb groups, and the latter are characterized by relatively restricted radiogenic isotope ratios. In general, high LIL/ HFSE ratios are best developed in low HFSE rocks, and the variation in LILE is less than that in HFSE. A local equilibrium model is developed in which the distinctive minor and trace element feature of arc rocks are the result of fluid percolation in the mantle wedge. Peridotite/fluid distribution coefficients are inferred to va..