Tectonics of the Miocene volcanism in E Hokkaido

It is proposed that the Miocene igneous belts in eastern Hokkaido extends down to the outer zone of Southwest Japan. Igneous rocks, such as 22 Ma-dacitic volcanic conglomerate in Holes 438 and 439, DSDP,and as a heat source for Jyouban hot spring, may connect both Miocene igneous belts. On the contrary the Miocene NE volcanic belt passes through the Oshima Peninsula and attains to the Sea of Japan. There was the zonal arrangement of middle Miocene to Pliocene igneous belts along the Japanese islands from the inner (back-arc) side to outer (trench) one : the arc, monogenic and forearc volcanic belts. The trench during this period was located less than about 100 km far from the forearc volcanic belt.