S-type and I-type granitic rocks of the Ohmine District, central Kii Peninsula
|Volume Title:||Ganseki Kobutsu Kosho Gakkai-Shi Journal of the Japanese Association of Mineralogists, Petrologists and Economic Geologists|
|Source:||Ganseki Kobutsu Kosho Gakkai-Shi = Journal of the Japanese Association of Mineralogists, Petrologists and Economic Geologists, 77(8), p.267-277. Publisher: Nippon Ganseki Kobutsu Kosho Gakkai, c/o: Tohoku Daigaku Rigakubu, Sendai, Japan. ISSN: 0021-4825|
|Note:||In Japanese with English summary. 2 p. refs.|
|Summary:||The Ohmine granitic rocks of Miocene age (14 m.y.) intrude sedimentary rocks of the Chichibu, Shimanto and Kumano groups in the central Kii Peninsula, SW Japan. The granitic rocks occur as small high-level plutonic masses; their petrography and chemistry indicate both I- and S-types. The I-type Dorogawa mass consists of fine-grained porphyritic granodiorite and granite. Its phenocrysts are euhedral to subhedral plagioclase, hornblende and biotite, and the groundmass is composed of quartz and orthoclase in micrographic intergrowth and plagioclase. The second I-type, Shirakura, mass is made up of fine-grained porphyritic hornblende granite. The Dorogawa mass is distinguished from the Shirakura by the absence of orthoclase phenocrysts and by a high MgO/(MgO + FeO*) ratio. The Shirakura granite is intruded by the S-type Kose granite. The S-type Kose, Asahi, Tenguyama and Shiratani masses consist of porphyritic granite, while the Katago-Mukuro masses are composed of granite porphyry with a small amount of quartz porphyry. These S-type rocks commonly contain orthoclase phenocrysts and muscovite; the Tenguyama and Shiratani masses characteristically include clots of sillimanite, andalusite, garnet, cordierite, orthopyroxene, biotite, corundum and green spinel, though the minerals are absent in the country rocks and xenoliths. [M.Ak.]|
|Subjects:||Cenozoic; Granites; Granodiorites; Igneous rocks; Major elements; Mineral composition; Miocene; Neogene; Petrology; Plutonic rocks; Stratigraphy; Tertiary; Textures; Asia; Far East; Honshu; Japan; Kii Peninsula; Ohmine; Type igne; Type sedimentaire|
|Copyright Information:||GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom, Reference includes data from PASCAL, Institute de l'Information Scientifique et Technique|
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