<国立科博専博>東北日本北部陸域における新第三紀火山活動 : その1.火山活動域の変遷

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The historical transition of the Miocene volcanic centers are deduced from the distribution of volcanic central facies (lavas and volcanic breccias) in the northern Honshu. Transitions of volcanic fields took place in the following four stages; 1) earlier than 18 Ma, 2) 18-15 Ma, 3) 15-12 Ma, 4) later than 12 Ma. In the first stage, volcanic activity in the northern Honshu was restricted to the area along the Japan Sea coast. The volcanic front shifted eastwards to the Backbone Range and reached the Pacific coast in the second stage. The southern part of the northern Honshu (Hachinohe∿the northern part of Iwate Prefecture) became a site of volcanic activity slightly later. Widening of the volcanic fields reached the climax at 15.5 Ma. The third stage was characterized by volcanism in a wide area after the opening of the Japan Sea. In the last stage, the volcanic front began to recede westwards to the eastern margin of the Backbone Range.
国立科学博物館の論文
1987-12-01