Abstract
Tuff breccia was found in Yamagata-mura, Kunohe-gun, Iwate-Prefecture. This tuff breccia contains many granitic and andesitic rocks with a small numbr of chert fragments. The matrix part of the tuff breccia is characterized by the presence of coarse, euhedral or corroded hornblende crystals. K-Ar age of the hornblende is dated as 16.1±2.0 Ma, and therefore, the tuff breccia is considered to be formed at the Middle Miocene in age. At the northern Kitakami Mountains, the area of Neogene magmatism should have been more extended 10 km to the east than that was considered before.
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Schedule a callMore From: The Journal of the Japanese Association of Mineralogists, Petrologists and Economic Geologists
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