This is a field project to collect rocks from the Chile Ridge in order to study the effects on magmatism when a spreading ridge is being subducted. The authors will test two hypotheses: (1) that the subducting slab acts as a cap on upwelling of the mantle and affects the foucsing of the magma to the ridge axis; (2) the break- up of the slab can provide exchange between ocean mantle and mantle under the arc. The authors will study the elemental and isotopic composition of rocks at varying distances from the trench.
