EEPS Colloquium: Paul Wallace

The Cascade Arc and the Subduction Zone Water Cycle

The Cascade arc is a warm-slab subduction zone characterized by the slow (3.5 cm/a) subduction of young (<10 Ma) oceanic crust. Elevated slab temperatures result in shallow dehydration beneath the forearc, providing a source of fluid at the base of the seismogenic zone and reduced slab flux to the mantle wedge beneath the volcanic arc. Calc-alkaline magmas formed in the mantle beneath the arc should therefore contain lower H2O and other volatile concentrations compared to arcs with cooler subducting plates. In this talk I test this hypothesis using data for mafic volcanics from different parts of the arc. The results can be used to investigate slab dehydration, magma formation processes, and along-arc variations, all in the context of the global subduction zone water cycle.

Host: Mike Krawczynski

EEPS colloquia are made possible by the William C. Ferguson Fund