Seismic Evidence of Mantle Wedge Controls on Volcano Distribution along Aleutian-Alaska

Date: 4/25/2019

Time: 02:30 PM

Room: Cascade II

The along-strike variation of volcanic activities has been observed at many subduction zones. However, direct structural constraints on how volcano distribution is influenced by slab geometry and mantle wedge properties are limited. Using full-wave ambient noise tomography, here we present a high-resolution shear-wave velocity model for the Aleutian-Alaska subduction zone. The new model reveals multiple slab segments with varied mantle wedge velocities, correlating with the distribution of active volcanoes and a volcanic gap. Low shear-wave velocities are observed within the mantle wedge associated with all of the three volcanic areas along strike, suggesting a wet environment. In particular, the distinct low-velocity mantle forearc atop the Pacific slab implies a highly hydrated mantle wedge associated with the Aleutian volcanic arc. The hydrated mantle wedge may facilitate melt and, consequently, the production of magma feeding the volcanoes. Contrastingly, the mantle wedge beneath the Denali volcanic gap, with much higher velocities, reflects a relatively dry environment. The tomographic result presented in this study provides evidence for the control of mantle wedge hydration states on magmatism at subduction zones and serves as a detailed structural framework for future modeling of slab deformation and mantle wedge dynamics.

Presenting Author: Xiaotao Yang

Authors