Figure F2. Geologic map of the southwest Japan forearc region and the Leg 190 Muroto and Ashizuri drilling transects. The Shimanto accretionary prism provides a landward analog of the Nankai accretionary prism. Note the widespread 17- to 12-Ma igneous activity, probably due to the initial subduction of the young Shikoku Basin oceanic lithosphere. Previous ODP/DSDP drill sites are shown by open circles. The dashed line shows the location of the cross section shown in Figure F3.