Along-arc variation in seismic velocity structure related to variable growth of arc crust in northern Izu-Bonin intraoceanic arc

作者：Obana Koichiro^*; Kamiya Shinichiro; Kodaira Shuichi; Suetsugu Daisuke; Takahashi Narumi; Takahashi Tsutomu; Tamura Yoshihiko

来源：Geochemistry Geophysics Geosystems, 2010, 11(8).

DOI：10.1029/2010GC003146

• seismic tomography
• mantle wedge
• crustal evolution
• Izu-Bonin
• intraoceanic arc
• subduction zone

The Izu-Bonin arc is an intraoceanic island arc where the Pacific plate subducts beneath the Philippine Sea plate. Along-arc variation in thickness of the arc crust has been observed by previous active seismic surveys beneath the Izu-Bonin arc. We have imaged three-dimensional (3-D) seismic velocity structures in the northern Izu-Bonin arc using arrival time data of the earthquakes during 80 days of observations by ocean bottom seismographs and three permanent island seismic stations. Our 3-D velocity model indicates heterogeneous structure in the mantle wedge along the arc. Low-velocity anomalies related to upwelling flow in the mantle wedge are not uniform beneath the volcanic front. Low-velocity anomalies extending down to the subducting slab beneath the volcanic front coincide with thicker parts of the arc crust north of Aoga-shima and south of Sumisu-jima. This coincidence suggests that heterogeneous mantle upwelling flow fundamentally controls the growth of the arc crust. Along topographic highs in the forearc, low-velocity anomalies in the crust and uppermost mantle coincide with positive magnetic anomalies suggesting the presence of a remnant arc, providing further evidence of this view of arc crust formation.

• 出版日期2010-8-11