Distribution of the Shimanto belt and geological map of the Murotohanto subbelt. (a) Distribution of the Shimanto belt in SW Japan. (b) Geological map of the Murotohanto subbelt (Eocene-Oligocene) on Muroto Peninsula (after Lewis et al. 2000) showing sample localities along the eastern (E1 to E4) and western coasts (W1 to W5). Sample E4 was taken from a large ex situ block of pillow lava interpreted to be from the Miocene Shiina volcanic rocks within the Nabae subbelt (e.g., Hibbard and Karig 1990; Mizoguchi et al. 2009).