Hydrothermal alteration of lowermost crustal rocks at Hess Deep, East Pacific Rise

• Project/Area Number: 25400515
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Petrology/Mineralogy/Economic geology
• Research Institution: Okayama University
• Principal Investigator: Toshio Nozaka 岡山大学, 自然科学研究科, 准教授 (80252948)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Project Status: Completed (Fiscal Year 2015)
• Budget Amount: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000); Fiscal Year 2015: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000); Fiscal Year 2014: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000); Fiscal Year 2013: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
• Keywords: 海洋底 / 下部地殻 / 斑れい岩 / 変質 / ヘスディープ / 深海掘削

Outline of Final Research Achievements

Green spinel, corundum and diaspore were found in primitive troctolites recovered from Hess Deep, East Pacific Rise. This is the first discovery of these aluminous minerals from the in-situ oceanic crust. Petrological studies revealed that the aluminous minerals were formed by high-temperature acidic hydrothermal fluids and subsequent alteration during cooling of the magmatic lower crustal rocks. In addition, it was revealed that serpentinization took place at three-stage alteration by fluids with variable silica and oxygen activities, and that magnetite formed at multiple stages under high and low temperature conditions. All of these findings are important for further understanding of hydrothermal activities near the fast-spreading axes.

Research Products

• [Int'l Joint Research] インディアナ大学(米国)
• [Int'l Joint Research] ベルゲン大学(ノルウェー)
• [Int'l Joint Research] プリマウス大学(英国)
• [Journal Article] Primitive layered gabbros from fast-spreading lower oceanic crust. (2013)
  • Author(s): Gillis, K. M., Snow, J. E., Klaus, A., Akizawa, N, 他26名
  • Journal Title: Nature Volume: 505 Issue: 7482 Pages: 204-207
  • DOI: 10.1038/nature12778
  • Peer Reviewed
• [Presentation] ヘス・ディープ・リフト斑れい岩類におけるかんらん石の蛇紋石化作用 (2015)
  • Author(s): 野坂俊夫・R.P. ウィンチ・R.メイヤー
  • Organizer: 日本鉱物科学会2015年会
  • Place of Presentation: 東京
  • Year and Date: 2015-09-25
• [Presentation] Multipolarity remanences in lower oceanic crustal gabbros recovered by drilling at Hess Deep (Integrated Ocean Drilling Program Expedition 345) (2015)
  • Author(s): Morris, A., Horst, A., Friedman, S., and Nozaka, T.
  • Organizer: European Geosciences Union General Assembly 2015
  • Place of Presentation: Vienna
  • Year and Date: 2015-04-12
  • Int'l Joint Research
• [Presentation] Hydrothermal Spinel, Corundum and Diaspore in Gabbroic Rocks from the Hess Deep Rift, IODP Site U1415 (2014)
  • Author(s): T. Nozaka, R. Meyer and R.P. Wintsch
  • Organizer: American Geophysical Union Fall Meeting
  • Place of Presentation: San Francisco
  • Year and Date: 2014-12-15 – 2014-12-19
• [Presentation] ヘスディープ・リフトのかんらん石斑れい岩類およびかんらん岩類における高温変質作用 (2014)
  • Author(s): 野坂俊夫・R.メイヤー・R.P. ウィンチ
  • Organizer: 日本地質学会第121年学術大会
  • Place of Presentation: 鹿児島
  • Year and Date: 2014-09-13 – 2014-09-15
• [Presentation] Olivine alteration - Part 1: High-T alteration in troctolite (2014)
  • Author(s): T. Nozaka, R.P. Wintsch and R. Meyer
  • Organizer: IODP Expedition 345 Second Postcruise Meeting
  • Place of Presentation: Monterey
  • Year and Date: 2014-06-14 – 2014-06-16
• [Presentation] IODP Exp. 345 成果：海洋底から初めて層状はんれい岩採取に成功 (2014)
  • Author(s): 阿部なつ江・秋澤紀克・針金由美子・星出隆志・町澄秋・前田仁一郎・野坂俊夫・ピトン-マリー・ギリス-キャサリン・スノー-ジョナサン・クラウス-アダム・IODP Exp. 345乗船研究者
  • Organizer: 日本地球惑星科学連合大会
  • Place of Presentation: 横浜
  • Year and Date: 2014-04-28 – 2014-05-02
• [Presentation] Static and fault-related alteration in the lower ocean crust, IODP Expedition 345, Hess Deep (2014)
  • Author(s): A. McCaig, K. Faak, N. Marks, T. Nozaka, M. Python, B. Wintsch, Y. Harigane, S. Titarenko, and Expedition 345 Science Party
  • Organizer: European Geosciences Union General Assembly 2014
  • Place of Presentation: Vienna
  • Year and Date: 2014-04-27 – 2014-05-02
• [Presentation] IODP Site U1415 ヘス・ディープ・リフトの斑れい岩類に産する緑色スピネルとダイアスポア (2013)
  • Author(s): 野坂俊夫・ ボブ-ウィンチ・ ロマン-メイヤー・IODP Expedition 345 乗船研究者一同
  • Organizer: 日本地質学会第120年学術大会
  • Place of Presentation: 仙台
• [Presentation] 高P/T型変成帯に産する低温変成蛇紋岩の変成組織 (2013)
  • Author(s): 上田康太郎・野坂俊夫
  • Organizer: 日本地質学会第120年学術大会
  • Place of Presentation: 仙台
• [Presentation] 鳥取県若桜地域の三郡変成帯に産する苦鉄質片岩の変成温度圧力条件 (2013)
  • Author(s): 柿田恭平・野坂俊夫
  • Organizer: 日本鉱物科学会2013年年会
  • Place of Presentation: つくば
• [Presentation] EPR Hess Deep Rift 斑れい岩類の変質作用 (2013)
  • Author(s): 野坂俊夫
  • Organizer: オフィオライトとマントル掘削への岩石学シンポジウム
  • Place of Presentation: 金沢
• [Presentation] Deep fast-spread Oceanic Crust - Fluid Intereactions: Petrography and Volatiles from IODP Expedition 345 Hess Deep Plutonic Crust (2013)
  • Author(s): Meyer, R., Wintsch, R.P., Nozaka, T., Gillis, K.M., Snow, J.E., and IODP Expedition 345 Shipboard Scientific Party
  • Organizer: Goldschmidt Conference 2013
  • Place of Presentation: Florence
• [Book] The Proceedings of the Integrated Ocean Drilling Program, Expedition 345, Hess Deep Plutonic Crust: Exploring the Plutonic Crust at a Fast-Spreading Ridge: New Drilling at Hess Deep (2014)
  • Author(s): K.M. Gillis, J.E. Snow, A. Klaus, and the Expedition 345 Scientists
  • Publisher: Integrated Ocean Drilling Program
• [Book] Hess Deep plutonic crust: exploring the plutonic crust at a fast-spreading ridge: new drilling at Hess Deep (2013)
  • Author(s): Expedition 345 Scientists
  • Total Pages: 89
  • Publisher: Integrated Ocean Drilling Program
• [Remarks] 人類未到の海洋底深部からの岩石の採取と分析に成功
  • URL: http://www.okayama-u.ac.jp/tp/release/release_id116.html
• [Remarks] 人類未到の海洋底深部からの岩石の採取と分析に成功
  • URL: http://www.okayama-u.ac.jp/tp/release/release_id116.html