アンデス山脈形成のトリガーとしての極乾燥環境形成:宇宙線生成核種による考察

• Project/Area Number: 18654084
• Research Category: Grant-in-Aid for Exploratory Research
• Allocation Type: Single-year Grants
• Research Field: Geology
• Research Institution: The University of Tokyo
• Principal Investigator: 横山 祐典 The University of Tokyo, 大学院・理学系研究科, 講師 (10359648)
• Co-Investigator(Kenkyū-buntansha): 松崎 浩之 東京大学, 工学系・研究科, 准教授 (60313194) ; 阪本 成一 国立天文台, ALMA推進室, 准教授 (60300711) ; 松本 拓也 大阪大学, 理学研究科, 助教 (50294145)
• Project Period (FY): 2006 – 2007
• Project Status: Completed (Fiscal Year 2007)
• Budget Amount: ¥3,200,000 (Direct Cost: ¥3,200,000); Fiscal Year 2007: ¥1,100,000 (Direct Cost: ¥1,100,000); Fiscal Year 2006: ¥2,100,000 (Direct Cost: ¥2,100,000)
• Keywords: アンデス山脈 / アタカマ砂漠 / 宇宙線生成核種 / 古気候 / テクトニクス / 古海洋 / 加速器質量分析 / 宇宙線

Research Abstract

アタカマ砂漠の乾燥化とアンデス山脈の隆起との関係についそ調べるため、チリのアンデス山脈から採取される岩石について宇宙線照射生成核種(CRN)をもちいた乾燥化の年代決定を行う実験法の確立を目指すことがこの研究の目的である。今年度は、これまでに本研究で遂行してきた実験結果をもとに地理情報システム(GIS)をつかって地形解析を行い、東京大学COE予算を用いてチリへ渡航し、経度と高度のことなる地点でのサンプリングを行った。代表者の横山と分担者の松崎、そして大学院生の城谷が参加し、研究協力者にあらたにAndres Veloso博士をくわえ、アントファガスタのVeloso博士の大学に拠点をおきながらのサンプリングを実施した。10月に行ったサンプリングの結果、採取したサンプルは合計300kgを超え、東部のカラマ周辺のサンプルについて10Beと26Alを用いた年代測定を行った。その結果、これまで考えられていた現地の岩石の照射年代よりもきわめて若い年代が得られた。アタカマ砂漠においては第四紀前期にはすでに極乾燥状態に入っていたというと考えられてきた。今回得られた結果は、これまで別の方法で決定された年代よりもオーダーで若いものであり、世界的にきわめて乾燥していると考えられている当地域の岩石についても、詳細な宇宙線生成核種による分析を行う必要があることを示唆しており、「地形学を含んだ地球表層プロセス研究において重要な知見となった。この結果は現在投稿準備中である。

Research Products

• [Journal Article] Prospects for the New Frontiers of Earth and Environmental Sciences. (2008)
  • Author(s): Yokoyama, Y., Matsuzaki, H., and Esat, T.M.
  • Journal Title: Quaternary Geochronology 3 Pages: 206-207
  • Peer Reviewed
• [Journal Article] Micropalaeontological evidence for Late Quaternary sea-level changes in Bonaparte Gulf, Australia. (2008)
  • Author(s): DeDeckker, P., and Yokoyama, Y.
  • Journal Title: Global and Planetary Changes 印刷中(掲載確定)
  • Peer Reviewed
• [Journal Article] Millennial-scale planktic foraminifer faunal variability in the East China Sea during the past 40,000 years (IMAGES MD012404 from the Okinawa Trough) (2008)
  • Author(s): Chang, Y.-Y., Wang, W.-L., Yokoyama, Y., Matsuzaki, H., Kawahata, H., and Chen, M.-T.
  • Journal Title: Terrestrial, Atmospheric and Ocean Sciences 印刷中(掲載確定)
  • Peer Reviewed
• [Journal Article] Issues in radiocarbon and U-series dating of corals from the last glacial period. (2008)
  • Author(s): Esat, T.M., and Yokoyama, Y.
  • Journal Title: Quaternary Geochronology 3 Pages: 244-252
  • Peer Reviewed
• [Journal Article] Identification of 1771 Meiwa Tsunami deposits using a combination of radiocarbon dating and oxygen isotope microprofiling of emerged massive Porites boulders. (2008)
  • Author(s): Suzuki, A., Yokoyama, Y, Kan, H., Minoshima, K., Matsuzaki, H., Hamanaka, N., and Kawahata, H.
  • Journal Title: Quaternary Geochronology 3 Pages: 226-234
  • Peer Reviewed
• [Journal Article] Relation between acid dissolution time in the vacuum test tube and time required for graphitization for AMS target preparation. (2007)
  • Author(s): Yokoyama, Y., Miyariri, Y., Matsuzaki, H., and Tsunomori, F.
  • Journal Title: Nuclear Instruments and Methods in Physics Research B 259 Pages: 330-334
  • Peer Reviewed
• [Journal Article] Japan Sea oxygen isotope stratigraphy and global sea-level changes for the last 50,000 years recorded in sediment cores from the Oki ridge. (2007)
  • Author(s): Yokoyama, Y., Kido, Y., Tada, R., Minami, I., Finkel, R.C., and Matsuzaki, H.
  • Journal Title: Palaeogeography, Palaeoclimatology, Palaeoecology 247 Pages: 5-17
  • Peer Reviewed
• [Journal Article] Age of glacial and periglacial landforms in northern Hokkaido, Japan, using OSL dating of fine grain quartz. (2007)
  • Author(s): Kondo, R., Tsukamoto, S., Tachibana, H., Miyairi, Y., and Yokoyama. Y.,
  • Journal Title: Quaternary Geochronology 2 Pages: 260-265
  • Peer Reviewed
• [Journal Article] Improvement of the 36Cl-AMS system at MALT using a Monte-Carlo ion-trajectory simulation in a gas-filled magnet. (2007)
  • Author(s): Aze, T., Matsuzaki, H., Matsumura, H., Nagai, H., Fujimura, M., Noguchi, M., Hongo, Y., and Yokoyama. Y.
  • Journal Title: Nuclear Instruments and Methods in Physics Research B 259 Pages: 144-148
  • Peer Reviewed
• [Journal Article] 深海堆積物の解析による最終氷期以降の南極半島周辺氷床の消長 (2007)
  • Author(s): 能美仁博, 横山祐典, 三浦英樹, 大河内直彦
  • Journal Title: 第四紀研究 46 Pages: 103-117
  • Peer Reviewed
• [Journal Article] Relation between acid dissolution time in the vacuum test tube and time required for graphitization for AMS target preparation. (2007)
  • Author(s): Yokoyama, Y., Miyairi, Y., Matsuzaki, H., Tsunomori, F.
  • Journal Title: Nuclear Instruments and Methods in Physics Research B (印刷中)
• [Journal Article] 放射性炭素を用いた気候変動および古海洋研究 (2007)
  • Author(s): 横山祐典
  • Journal Title: 真空 (印刷中)
  • NAID: 10019750291
• [Journal Article] Improvement of the ^<36>Cl-AMS system at MALT using a Monte-Carlo ion-trajectory simulation in a gas-filled magnet. (2007)
  • Author(s): Aze, T., Matsuzaki, H., Matsumura, H., Nagai, H., Fujimura, M., Noguchi, M., Hongo, Y., Yokoyama Y.
  • Journal Title: Nuclear Instruments and Methods in Physics Research B (印刷中)
• [Journal Article] Japan Sea Oxygen isotope stratigraphy and global sea-level changes for the last 50,000 years recorded in sediment cores from the Oki ridge. (2007)
  • Author(s): Yokoyama, Y., Kido Y., Tada, R., Minami, I., Finkel, R.C., Matsuzaki, H.
  • Journal Title: Palaeogeography, Palaeoclimatology, Palaeoecology 247 Pages: 5-17
• [Journal Article] 深海底堆積物の解析による最終氷期以降の南極半島周辺氷床の消長 (2007)
  • Author(s): 能美仁博, 横山祐典, 三浦英樹, 大河内直彦
  • Journal Title: 第四紀研究 46 Pages: 103-117
  • NAID: 10023992659
• [Journal Article] Age of glacial and periglacial landforms in northern Hokkaido, Japan, using OSL dating of fine grain quartz. (2007)
  • Author(s): Kondo, R., Tsukamoto, S., Tachibana, H., Miyairi, Y., Yokoyama, Y.
  • Journal Title: Quaternary Geochronology 2 Pages: 260-265
• [Journal Article] Dust influx reconstruction during the last 26,000 years inferred from a sedimentary leaf wax record from the Japan Sea. (2006)
  • Author(s): Yokoyama, Y., Naruse, T., Ogawa, N.O., Tada, R., Kitazato, H., Ohkouchi, N.
  • Journal Title: Global and Planetary Change 54 Pages: 239-250
• [Journal Article] Comment on "Extending the radiocarbon calibration beyond 26,000 years before present using fossil corals" by T.-C. Chiu, R.G. Fairbanks,R.A. Mortlock, and A.L. Bloom. (Quaternary Science Reviews 24 (2005)1797-1808). (2006)
  • Author(s): Yokoyama, Y., Esat, T.M.
  • Journal Title: Quaternary Science Reviews 25 Pages: 3081-3083
• [Journal Article] Sea-level during the early deglaciation period in the Great Barrier Reef, Australia. (2006)
  • Author(s): Yokoyama, Y., Purcell, A., Marshall, J.F., Lambeck, K
  • Journal Title: Global and Planetary Changes 53 Pages: 147-153
• [Journal Article] Variability in the Uranium isotopic composition of the oceans over glacial-interglacial timescales. (2006)
  • Author(s): Esat, T.M., Yokoyama, Y.
  • Journal Title: Geochimica et Cosmochimica Acta 70 Pages: 4140-4150
• [Journal Article] Growth Patterns of the Last Ice Age Coral Terraces at Huon Peninsula (2006)
  • Author(s): Esat, T.M., Yokoyama, Y.
  • Journal Title: Global and Planetary Changes 54 Pages: 216-224
• [Journal Article] Micropaleontological successions in the Panama Basin during the last deglaciation : response to sea-surface productivity induced by a transient climate change. (2006)
  • Author(s): Martinez, J.I., Rincon D., Yokoyama, Y., Barrows, T.T
  • Journal Title: Palaeogeography, Palaeoclimatology, Palaeoecology 234 Pages: 114-126
• [Presentation] In-situ宇宙線照射生成核種(Be-10, Al-26)を用いた南米チリ・アタカマ砂漠における乾燥化の研究 (2007)
  • Author(s): 城谷和代, 横山祐典, 阪本成一.松崎浩之
  • Organizer: 第2回東京大学原子力シンポジウム
  • Place of Presentation: 東京大学、東京
  • Year and Date: 2007-04-24
• [Presentation] Last glacial sea level recorded in the far field marine sediment cores from marginal seas. (Keynote, INVITED) (2007)
  • Author(s): Yokoyama, Y., and Lambeck, K.
  • Organizer: .XVII INQUA (International Union for Quaternary Research) Congress
  • Place of Presentation: オーストラリア、ケアンズ
• [Presentation] Reconstruction of the East Antarctic Ice Sheet history along the Skarvsnes coast using in situ produced cosmogenic nuclides. (2007)
  • Author(s): Yamane, Y., Yokoyama, Y., Miura, H., Maemoku, H., Iwasaki, S., and Matsuzaki, H.
  • Organizer: .XVII INQUA (International Union for Quaternary Research) Congress
  • Place of Presentation: オーストラリア、ケアンズ
• [Presentation] 宇宙線照射生成核種を用いた南米チリ・アタカマ砂漠における地表面露出年代測定 (2007)
  • Author(s): 城谷和代, 横山祐典, 松崎浩之, Eugenio E. Veloso
  • Organizer: 第10回AMSシンポジウム
  • Place of Presentation: 武田先端知ビル、東京
• [Book] 地球史が語る近未来の環境・第2章 (2007)
  • Author(s): 横山祐典
  • Total Pages: 237
  • Publisher: 東京大学出版会