東北本州弧外側第三系の地質とその発達史  [in Japanese] Tertiary geology and its geological development of the outer zone of northeast Honshu Arc  [in Japanese]

The Outer Northeast Honshu Arc is underlain by the Paleogene and Neogene Systems and their pre-Tertiary basement rocks. The Paleogene System is exposed in small areas of the Pacific side, which are the Paleocene Heizaki Dacite, the Eocene Noda and Kogawa Groups and the Jodogahama Rhyolite, and the Oligocene Shiramizu Group. The Neogene System is widely distributed in Sannohe, Sendai-Matsushima and Joban areas. The lower part of the Lower Miocene Seriesis characterized by a huge amount of terrestrial effusive rocks. The middle-upper part of the Lower Miocene to the lower-middle part of the Upper Miocene are composed mainly of sandy-silty sediments deposited during marine transgression. The upper part of the Upper Miocene is chiefly made up of acidic pyrocrastic flows. The Pliocene Series was accumulated during two times of marine transgression. The stratigraphic relationship, volcanic activities and tectonic events recognized in the Tertiary sequences are interpreted by both the convergence rate of plate (OTSUKI, 1984, 1986) and the eustatic sea level change (HAQ, et al., 1987).