Journal of the Faculty of Science, Hokkaido University. Series 4, Geology and mineralogy;Vol.XVIII, No.3

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Fossil Rootless Fumaroles in the Noboribetsu Pumice Flow Deposits and Their Alteration Products in the Noboribetsu Formation, Kuttara Volcano, Southwestern Hokkaido, Japan

Kawachi, Shimpei;Ishii, Jiro;Matsui, Masaru;Miyasaka, Seigo;Nakajima, Masahiro;Kiminami, Kazuo;Kontani, Yoshihiro;Yamazaki, Tetsuyoshi;Hanabusa, Hiroshi;Kimura, Gaku;Shuto, Takami;Maniwa, Ken

Permalink : http://hdl.handle.net/2115/34850
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Abstract

Many fossil rootless fumaroles are found in the upper unwelded facies of the Noboribetsu Pumice Flow Deposits, which are distributed around the Kuttara Caldera, SW Hokkaido. Rootless crater pits immediately above the fumaroles are filled by pumice, scoria, ash, and mud of the Noboribetsu Formation overlying the Noboribetsu Pumice Flow Deposits. Alteration due to the fumarolic action clearly extends into the Noboribetsu Formation. The origin of the Noboribetsu Formation is suggested to be a base surge deposit based on its distribution and lithological characteristics.

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