1 0 0 0 OA オホーツク海のメタンハイドレートとプルーム
- 著者
- 庄子 仁 JIN Young K OBZHIROV Anatoly SALOMATIN Alexander BARANOV Boris GLADYSH Vyacheslav 八久保 晶弘 南 尚嗣 山下 聡 高橋 信夫 SHOJI Hitoshi HACHIKUBO Akihiro MINAMI Hirotsugu YAMASHITA Satoshi TAKAHASHI Nobuo
- 出版者
- 東京地学協会
- 雑誌
- 地學雜誌
- 巻号頁・発行日
- vol.118, no.1, pp.175-193, 2009-03
- 被引用文献数
- 10
1 0 0 0 OA 極域アイスコアに記録された地球環境変動
1 0 0 0 IR 南アルプス南部, 大聖寺平および丸山における風食ノッチの発達プロセス
- 著者
- 小山 拓志
- 出版者
- 東京地学協会
- 雑誌
- 地學雜誌 (ISSN:0022135X)
- 巻号頁・発行日
- vol.120, no.6, pp.981-992, 2011-12-25
- 参考文献数
- 19
Turf scarps and patch-shaped barelands are clearly observed on windy alpine ridges and wind-swept slopes of Japanese mountains. This study investigates the formation and retreat of turf scarps at the Daisyoujidaira site (2700 m a.s.l.) and Maru-yama site (3025 m a.s.l.), Southern Japanese Alps.<br> The average distances of scarp retreat are 2.2 cm/2 years (Daisyoujidaira site: 2006-2008), 0.5 cm/year (Maru-yama site: 2006-2007), and 3.6 cm/year (Maru-yama site: 2007-2008).<br> At the Daisyoujidaira site, generation of turf scarps started on the walls of trails or gullies. The retreat processes of turf scarps are considered to be a combination of frost-thaw action (needle ice creep), deflation, rain-splash erosion, and slope wash. However, at the Daisyoujidaira site, turf scarps with curtain-like exposure of plant roots are protected from deflation and rain-splash erosion during summer.<br> On the other hand, at the Maru-yama site, eave collapsing and turf plucking occur frequently, and turf scarps continue to retreat. As a result, patch-shaped barelands continue to expand on the wind-swept slope of Maru-yama.
- 著者
- 松本 剛 宮下 純夫 荒井 章司 森下 知晃 前田 仁一郎 熊谷 英憲 大友 幸子 DICK Henry J. B.
- 出版者
- 東京地学協会
- 雑誌
- 地學雜誌 (ISSN:0022135X)
- 巻号頁・発行日
- vol.112, no.5, pp.705-719, 2003-10-25
- 参考文献数
- 20
- 被引用文献数
- 6 4
To characterise the crust-mantle boundary (petrological Moho) and to find evidence of ophiolite model, we investigated the lithology and the development process of the oceanic crust. We carried out geological and geophysical studies of Atlantis Bank core complex located at the eastern margin of the Atlantis-II active transform in the Southwest Indian Ridge (SWIR) using deep sea submersibles and remotely operated vehicles. Unaltered lower crust and uppermost mantle rocks were observed at the southwestern slope of Atlantis Bank. The lower crust of this part of Atlantis Bank is similar to the ophiolite exposed ashore. On the other hand, a large number of dike intrusions into gabbroic massifs were observed at the eastern wall and at the southern slope of the bank. This corresponds to the dike-gabbro transition in the ophiolite model. Dike intrusions were also observed in the mantle peridotite domains. This may, however, suggest melt intrusions into the bank near the spreading axis posterior to the mantle peridotite that was dragged out along the detachment faults, or may suggest possible horizontal melt intrusion from the segment centre to the segment edge characterised by a thin plutonic layer. The northern ridge-transform intersection RTI of the Atlantis-II active transform presents an L-shaped nodal basin, while the southern RTI presents a V-shaped one. The difference between northern and southern RTI types suggests differences in the structure and basement rock types. A fossil transform fault and RTI relics at the northern side of the spreading axis west of the Atlantis-II active transform were observed, suggesting a sudden change of the spreading direction in SWIR from 20 Ma