仙台周辺の新第三紀火山活動の研究(I)

高館層について

抄録

The Takadate formation (lower Miocene) is distributed in the northern part of the Abukuma plateau. This area is an upheaval (or not-subsiding) zone through the “green-tuff period”, defined by the Futaba fault, the Kagitori-Okubusi line and the Morioka-Sirakawa line.
The Takadate formation covers the Tsukinoki formation conformably, and is composed of volcanic rocks as follows: olivine-basalt, hypersthenebasalt, bytownite-basalt, (pigeonite)-augite- hypersthene-basalt_??_andesite, augite-hypersthene-andesite (P. series), augite-hypersthene-andesite (H. series), hornblende-andesite, and hypersthene-hornblende-rhyolite.
These volcanic rocks are the products of fissure eruption along the two upheaval mobile zones extending from south to north.
It is concluded that the Takadate formation, as well as Ryozen formation, is the products of the igneous activities related with violent fructuring movement of the earth crust in the originating stage of the “green-tuff region”.