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Slab‐derived fluids, fore‐arc hydration, and sub‐arc magmatism beneath Kyushu, Japan
Author(s) -
Saita Hiroto,
Nakajima Junichi,
Shiina Takahiro,
Kimura JunIchi
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl063084
Subject(s) - geology , attenuation , mantle (geology) , slab , mantle wedge , seismology , volcano , peridotite , island arc , geophysics , tectonics , subduction , petrology , physics , optics
We estimate the three‐dimensional (3‐D) P wave attenuation structure beneath Kyushu, Japan, using a large number of high‐quality waveform data. Our results show that the mantle wedge is characterized by high‐attenuation regions in the fore‐arc corner and in the back‐arc beneath volcanoes, with the two regions separated by a low‐attenuation area. The volcanic gap in central Kyushu is underlain by low attenuation below the Moho. High attenuation in the fore arc is probably associated with serpentinized peridotite, while that in the back arc is interpreted as an upwelling flow that is the source of arc magmas. The presence of low‐attenuation mantle that separates the high‐attenuation hydrated, fore‐arc, and back‐arc mantle regions suggests that fluids are supplied from two depth levels of the slab by different mechanisms. Low attenuation beneath the volcanic gap probably results from intricate 3‐D mantle flow that is caused by tectonic processes such as back‐arc extension and ridge collision.