Fig. 1: Regional map of the Izu-Bonin-Mariana convergent plate margin with sampling locations.
From: Boron isotopes in boninites document rapid changes in slab inputs during subduction initiation
a, b Locations of the International Ocean Discovery Program Expedition 352 drill sites in the Izu-Bonin forearc, Western Pacific. U1439 and U1442 are boninite sites, while U1440 and U1441 are forearc basalt sites. c Simplified logs for the two boninite holes (U1439C and U1442A), recovering lavas and dykes mainly of high-silica (HSB) and low-silica (LSB) boninites and their differentiation products, high magnesium andesites (HMA). The depths in the cores for each sample examined this study and HSB samples from Li et al.4 (light blue squares) are plotted alongside the core logs. The depth of two HSB samples from hole U1439A (In brackets) are also plotted alongside hole U1439C. For the purposes of this study HMA differentiates are not distinguished from their parental HSB or LSB. SB: Shikoku Basin; PVB: Parece Vela Basin; MT: Mariana Trough; KPR: Kyushu Palau Ridge; WPB: West Philippine Basin; AP: Amami Plateau; DR: Daito Ridge; ODR: Oki-Daito Ridge; mbsf: meters below the seafloor.
