Abstract
We have developed an improved method for examining the metamorphic history of subducting oceanic crust and its impact on chemical cycling at convergent margins. Our approach provides a much-needed metamorphic complement to records of subduction-zone cycling derived from studies of igneous rocks produced at volcanic arcs. By merging methods utilizing garnet zoning to establish prograde reaction histories with in situ high-resolution trace element geochemistry, and application to coesite eclogites representing subduction to depths beneath arcs, we are able to directly identify geochemical manifestations of reactions contributing to element mobility in the subducting slab that are only inferred in studies of volcanic arcs or theoretical metamorphic models.
