Abstract
Across-arc Li-B-Pb isotope systematics, together with trace element geochemistry and phase relationships in subducting slabs are used to understand the petrogenesis of lavas from the northeastern Japan arc. Our results suggest that accessory minerals and minor phases in the subducting slab play important roles in determining the chemical compositions of fluid released by dehydration. The strikingly different results for the northeastern Japan arc and the Izu arc in Li isotope across-arc variation show that not only chemical characteristics of the subducting slab but also the physical characteristics of the subduction zone could affect the Li isotope compositions of subducting slabs, producing heterogeneity in the Li isotope composition of the mantle.
