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Figure F22. A. Bathymetric map of rear-arc region behind Aogashima, Myojin Knoll, Myojinsho, and Sumisu arc-front volcanoes (shown in Fig. F11). 40Ar/39Ar and K-Ar ages from Ishizuka et al. (2003b). Older ages (~12.5–3 Ma) from basalts to rhyolites of the rear-arc seamount chain volcanoes; younger ages (<3 Ma) from bimodal volcanic rocks in the broad zone of extension that overlaps with the eastern half of the rear-arc seamount chains; youngest ages (<1 Ma) from bimodal volcanic rocks of the narrow active rift (see Fig. F6). Site U1437 lies in a volcano-bounded basin (Fig. F15A) between the Manji and Enpo rear-arc seamount chains, at the foot of the flat-topped Manji Volcano, which was presumably beveled by wave action. (Continued on next page.)

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