摘要：A previous study of a longitudinal profile along the Bonin ridge concluded that remarkably thin forearc crust (< 10 km thick) along the northern half of the ridge indicates that the crust there was formed by forearc spreading during the initial stage of subduction along the Izu-Bonin intra-oceanic arc.However, a profile across the Bonin ridge shows a thicker crust.In this study, we construct a model that takes into account seismic and gravity data from both profiles.Re-modeling of the seismic data showed a north-south aligned area of thin crust (∼10 km thick) at the center of the Bonin ridge; this structure was confirmed by gravity data.The seismic data at the eastern end of the across-arc profile suggests that the crust thickens beneath the trenchward slope of the Bonin ridge.However, a petrological model suggests a trenchward extension of forearc oceanic crust that formed during the initial stage of subduction.Although further detailed investigation is required, we suggest that this contradiction can be explained either by the subduction of buoyant crust immediately beneath the forearc oceanic crust, or by the presence of a serpentinized mantle wedge beneath the forearc oceanic crust. Key words Seismic imaging gravity forearc Bonin ridge subduction zone.
关键词：Seismic imaging ;gravity ;forearc ;Bonin ridge ;subduction zone
