title: Pathway from subducting slab to surface for melt and fluids beneath Mount Rainier.
abstract: Convergent margin volcanism originates with partial melting, primarily of the upper mantle, into which the subducting slab descends. Melting of this material can occur in one of two ways. The flow induced in the mantle by the slab can result in upwelling and melting through adiabatic decompression. Alternatively, fluids released from the descending slab through dehydration reactions can migrate into the hot mantle wedge, inducing melting by lowering the solidus temperature. The two mechanisms are not mutually exclusive. In either case, the buoyant melts make their way towards the surface to reside in the crust or to be extruded as lava. Here we use magnetotelluric data collected across the central state of Washington, USA, to image the complete pathway for the fluid-melt phase. By incorporating constraints from a collocated seismic study into the magnetotelluric inversion process, we obtain superior constraints on the fluids and melt in a subduction setting. Specifically, we are able to identify and connect fluid release at or near the top of the slab, migration of fluids into the overlying mantle wedge, melting in the wedge, and transport of the melt/fluid phase to a reservoir in the crust beneath Mt Rainier.
authors.affiliation: Department of Geology and Geophysics, MS#22, Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, Massachusetts 02543, USA.
authors.forename: R Shane
authors.initials: RS
authors.lastname: McGary
authors.affiliation: Department of Geology and Geophysics, MS#22, Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, Massachusetts 02543, USA.
authors.forename: Rob L
authors.initials: RL
authors.lastname: Evans
authors.affiliation: Energy and Geoscience Institute, University of Utah, 423 Wakara Way, Suite 300, Salt Lake City, Utah 84108, USA.
authors.forename: Philip E
authors.initials: PE
authors.lastname: Wannamaker
authors.affiliation: Department of Geology and Geophysics, MS#22, Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, Massachusetts 02543, USA.
authors.forename: Jimmy
authors.initials: J
authors.lastname: Elsenbeck
authors.affiliation: Department of Earth Science, University of Bergen, Allegaten 41, 5007 Bergen, Norway.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Rondenay