Seismic imaging of subduction zone metamorphism

Publication Type  Journal Article
Year of Publication  2008
Authors  Rondenay, S.; Abers, G. A.; Van Keken, P. E.
Journal Title  Geology
Volume  36
Issue  4
Pages  275-278
Journal Date  Apr
ISBN Number  0091-7613
Accession Number  ISI:000254641700001
Key Words  subduction; oceanic crust; seismic studies; metamorphism; eclogite; water; teleseismic body waves; multiparameter 2-dimensional inversion; dehydration reactions; crustal thickness; central alaska; mantle; beneath; water; slabs; arc
Abstract  

Combined analysis of high-resolution seismic images of the Alaska and Cascadia subduction zones reveals where metamorphic fluids are released. Both images show the subducted oceanic crust as a dipping low-velocity layer with a clear termination depth. However, in Alaska the crust is thicker (15-20 km compared to 8 km) and terminates at greater depth (120 km compared to 40 km) than in Cascadia. Based on metamorphic reaction estimates and geodynamic models, we demonstrate that the termination depth corresponds to eclogitization of the crust triggered by dehydration of water-bearing minerals, and that the location of this reaction is dependent on the thermal structure of the subducted slab.

Notes  

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URL  <Go to ISI>://000254641700001
DOI  Doi 10.1130/G24112a.1