Seismic imaging of subduction zone metamorphism
Abstract
Combined analysis of high-resolution seismic images of the Alaskaand Cascadia subduction zones reveals where metamorphic fluidsare released. Both images show the subducted oceanic crust asa dipping low-velocity layer with a clear termination depth.However, in Alaska the crust is thicker (15-20 km comparedto 8 km) and terminates at greater depth (120 km compared to40 km) than in Cascadia. Based on metamorphic reaction estimatesand geodynamic models, we demonstrate that the termination depthcorresponds to eclogitization of the crust triggered by dehydrationof water-bearing minerals, and that the location of this reactionis dependent on the thermal structure of the subducted slab.
- Publication:
-
Geology
- Pub Date:
- April 2008
- DOI:
- 10.1130/G24112A.1
- Bibcode:
- 2008Geo....36..275R