Seismic imaging of mantle wedge corner flow and arc magmatism

Proceedings of the Japan Academy, Series B. Physical and Biological Sciences

Akira HASEGAWA¹ 

[1] Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University

关键词: corner flow;    arc magmatism;    mantle wedge;    H2O;    seismic tomography;   

DOI  :  10.2183/pjab.94.015

学科分类：物理（综合）

来源: Japan Academy

【 摘 要 】

I reviewed studies on the inhomogeneous seismic structure of the mantle wedge in subduction zones, in relation to corner flow and its implications for arc magmatism. Seismic studies in Tohoku clearly imaged the descending flow portion of the corner flow as a thin seismic low-velocity layer right above the slab. Slab-derived H2O is fixed to the layer as hydrous minerals, which are brought down by the slab and eventually decompose. The released H2O rises and encounters the ascending flow, formed to fill the gap caused by the descending flow. The combination of H2O addition and adiabatic decompression causes partial melting within the ascending flow. For many subduction zones, seismic tomography has distinctly imaged the ascending flow of the corner flow as a seismic low-velocity and/or high-attenuation layer in the mantle wedge inclined nearly parallel to the slab. These observations indicate that the volcanic front in subduction zones is formed both by the ascending flow and the addition of slab-derived H2O.

【 授权许可】

Unknown