Ca-Fe-rich pyroxenes in Miocene perlites from the Tsugawa and Tadami areas, northeast JAPAN.

Shimazu, Mitsuo; Takano, Masaki

doi:10.2465/ganko1941.72.419

Cited by 5 publications

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“…Aphyric tholeiitic andesite similar to icelandite named by Carmichael (1964) is rare in Japan and was reported only from the Ashio and Shidara areas (Kuno, 1969), while tholeiitic dacite and rhyolite were reported from the Aizu-Tadami area (Shimazu and Takano, 1977) and Motegi area (Shiramizu et al, 1983).…”

Section: Introductionmentioning

confidence: 99%

Tholeiitic andesite and dacite of early Pleistocene age in Shikumi area, Niigata Prefecture, Japan.

Shimazu

Igarashi

Ohashi

1985

J. Japan. Assoc. Min. Petr. Econ. Geol.

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Aphyric tholeiitic andesite lavas are interbedded with the Middle Formation of the Uonuma Group of early Pleistocene age. The aphyric andesite contains microphenocrysts of augite , h ypersthene, plagioclase and olivine, and groundmass crystals of acicular plagioclase, pigeonite and subcalcic ferroaugite and is petrographically similar to icelandite . Tholeiitic dacite is found as small fragments in lapilli tuff and as large blocks in mud flow deposit . It contains microphenocrysts of ferroaugite, ferrohypersthene and plagioclase , and groundmass crystals of acicular plagioclase and ferropigeonite. Some of the dacites contain ferrohortonolite surrounded by pigeonite grains.From whole rock compositions and mineralogy of constituent minerals , the aphyric tholeiitic andesite and dacite are thought to be differentiated from tholeiitic magma which may have nearly the same chemical composition as that of the basalt xennlith in the anhvrir -4-if.

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Section: Introductionmentioning

confidence: 99%