三浦半島下部中新統葉山層群中に見出された安山岩貫入岩体の産状,化学組成及び年代
1988 年 33 巻 2 号 p. 59-66
詳細
1988 年 33 巻 2 号 p. 59-66
An intrusive andesile rock was found for the first time in the Miocene Hayama Group, Miura Peninsula, northeast of the Sagami Trough, Central Japan. This andesite has a chilled contact with the surrounding mudstone of the lowermost part of the Hayama Group. Major and trace element chemical analyses of the andesite verified that it is a high-K andesite of arc affinity. A K-Ar age of 23.4±0.8 Ma shows that the intrution of the andesite magma took place just after the deposition of the mudstone of the Hayama Group. This data suggest that the Hayama Group probably represents earliest Miocene fore-arc sedimentation associated with andesitc fore-arc volcanism.
