新潟地域の魚沼ピンクテフラ層の広域対比の検討

概要

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Widearea correlation of the Uonuma Pink Tephra Bed (about 0.95Ma) in the Niigata region to the several Tephra Beds in the northeast and central Japan was attempted. The correlation was examined on the basis of their lithology, petrography and chemical composition of glass shards. The U8 Tephra Bed in the Umegase Formation in the Boso Peninsula was surely confirmed in correlation and the chemical composition of the glass shards is characteristic showing higher content of FeO (1.7-1.9%), CaO (around 1.8%), Tio_2(around 0.3%) and MgO (0.30-0.35%) as similar to the Uonuma Pink Tephra among silicic tephras in Japan. The Tamatsukuri Tephra Bed in northwest Miyagi Prefecture represents very similar unit sequence as the Uonuma Pink Tephra Bed in addition to the petrographical similalities, and can be possibly correlated. Besides, in the Aizu region, a candidate Tephra Bed for widearea correlation was found out. Thus the Uonuma Pink Tephra Bed was revealed as the one of the prominent widespread Tephras in northeastern and central Japan in early Pleistocene.
新潟大学教育人間科学部の論文