@article{oai:kumadai.repo.nii.ac.jp:00024674,
 author = {Yokose, Hisayoshi and Sato, Hajime and Fujimoto, Yuta and 小林, 哲夫 and Kobayashi, Tetsuo and Akimoto, Kazumi and 秋元, 和實 and Yoshimura, Hiroshi and Morii, Yasuhiro and Yamawaki, Nobuhiro and Ishii, Teruaki and Honza, Eiichi and 横瀬, 久芳 and 佐藤, 創 and 藤本, 悠太 and Maria Hannah, T. MIRABUENO and 小林, 哲夫 and Akimoto, Kazumi and 秋元, 和實 and 吉村, 浩 and 森井, 康宏 and 山脇, 信博 and 石井, 輝秋 and 本座, 栄一},
 issue = {1},
 journal = {地学雑誌},
 month = {May},
 note = {application/pdf, 論文(Article), To understand the submarine volcanism surrounding the Tokara Islands, a submarine topographic analysis and 67 dredge samplings were carried out. Prior to the submarine investigations, we reviewed comprehensively geological and geophysical data on this region and confirmed the complexity of both volcanic activity and tectonic setting of the Tokara Islands. In contrast to the homogeneous subaerial volcanic rocks comprising predominantly two-pyroxene andesite lava flows, the dredged samples vary from basaltic andesite to rhyolite in composition. Furthermore, we reveal that dacitic and rhyolitic pumices are abundant and broadly distributed throughout the submarine area. The recovered volcanic rocks were mainly subangular to angular cobble-boulder fragments of lava, scoria, and variably vesiculated pumice. Volcanic rocks with hornblende phenocrysts occur only north of the Tokara strike-slip fault, which is a major tectonic element of volcanism., The pumices can be classified into three categories based on the size and abundance of the phenocrysts: aphyric pumice, fine-grained porphyritic pumice, and coarse-grained porphyritic pumice. Occurrences, such as amount in a dredge, shape without extensive abrasion, large fragment size, and bulk rock chemical compositions of the major pumice fragments suggest that they are in situ, rather than originating as drifted pumice or air fall, exotic pyroclastic fragments derived from the four super-eruptions of Kyushu Island. Because dredged samples contained fresh volcanic glass in the groundmass, and are not covered by iron-manganese oxide crust, they appear to have originated from the Quaternary eruptions. Indeed volcanic islands have developed above the submarine erosional terraces (indicated as knick points at approximately 110 m in depth), which is assumed to have formed during the last glacial age. K-Ar age dating on the representative pumice samples resulted in ages of 0.60 ± 0.20 Ma and < 0.2 Ma, respectively. These newly obtained submarine data support that acidic volcanisms occurred around the submarine calderas during the Mid-Pleistocene age., http://www.jstage.jst.go.jp/article/jgeography/119/1/119_46/_article/-char/ja/},
 pages = {46--68},
 title = {トカラ列島における中期更新世の酸性海底火山活動},
 volume = {119},
 year = {2010},
 yomi = {コバヤシ, テツオ and アキモト, カズミ and アキモト, カズミ}
}