Subduction Zone Magmas

A focus of this research group has been the study of magmatic processes in subduction zone environments. Interests in this problem are wide-ranging. One recent area of focus is on the conditions and processes that lead to the unique major and trace element abundance signatures observed in subduction zone magmas. Quantifying the role of H2O in the melt generation process is also of central interest. By obtaining estimates of pre-eruptive H2O contents of primitive arc magmas, we can infer the source of this volatile and estimate the trace element and isotopic compositions of elements that are added when a fluid-rich component is derived from the slab and added to the overlying mantle wedge. Our work in the Mt.Shasta region of California shows that a fluid released by the dehydration of minerals carried in the subducting slab contributes most of the trace element signature to subduction zone magmas. This trace element rich fluid flux-melts the overlying mantle it ascends into the hot, shallower portion of the mantle wedge, and the final melt products are sampled from the shallowest depths at the top of the mantle wedge.