The objective of this project is to estimate the incompatible element composition of material subducted into the deep mantle. The composition of material subducted into the deep mantle (the "deep mantle subduction flux") differs from the composition of material subducted at the plate boundary (the "trench subduction flux") because some fraction of this material finds its way into subduction zone magmas ("the arc flux"). Since the deep mantle subduction flux is equal to the trench subduction flux less the arc flux, the deep mantle subduction flux can be determined if the trench subduction flux and arc fluxes are known. There is now a sufficiently advanced understanding of subduction zone processes and sufficient literature data for this to be done. This study will determine the trench subduction, arc, and deep mantle subduction fluxes for 8 arcs. New analytical work will be carried out to estimate the incompatible and isotopic composition of sediment being subducted adjacent the Andean southern volcanic zone; the study will otherwise make use of previously published data available in on-line databases. Estimates of the deep mantle subduction flux should allow more quantitative tests of broad ideas about the evolution of the Earth, including (1) the proposition that recycled oceanic crust and sediment is present in deep mantle plumes, (2) that subduction zone magmatism is the principal mechanism of the continental crust creation, and (3) that sediment subduction is an important control on the composition and volume of the continental crust. Broader impacts include graduate training (the study will constitute a doctoral dissertation) and participation of a member of an underrepresented group in research.
