Investigation on variations of the geomagnetic paleo-intensity using deep-tow and sea-surface magnetic anomalies
| Project/Area Number |
15H05207
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 海外学術 |
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| Research Field |
Solid earth and planetary physics
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| Research Institution | Kobe University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
沖野 郷子 東京大学, 大気海洋研究所, 教授 (30313191)
佐藤 太一 国立研究開発法人産業技術総合研究所, 地質調査総合センター, 主任研究員 (50613246)
野木 義史 国立極地研究所, 研究教育系, 教授 (90280536)
藤井 昌和 国立極地研究所, 研究教育系, 助教 (80780486)
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| Project Period (FY) |
2015-04-01 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥16,120,000 (Direct Cost: ¥12,400,000、Indirect Cost: ¥3,720,000)
Fiscal Year 2018: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
Fiscal Year 2017: ¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2016: ¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000)
Fiscal Year 2015: ¥5,200,000 (Direct Cost: ¥4,000,000、Indirect Cost: ¥1,200,000)
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| Keywords | 地球磁場変動 / 地磁気異常 / 海洋底の磁化 |
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| Outline of Final Research Achievements |
The Cretaceous Normal Superchron (CNS) is a ~40 Myr-long period extending between Chrons M0 and 34 (~120-83 Ma) during which the geomagnetic field polarity remained normal. Systematic variations of the geomagnetic paleointensity have been suggested based on a deep-tow magnetic profile acquired in the Central Atlantic Ocean and selected sea-surface magnetic profiles worldwide crossing the whole CNS (Granot et al., 2012). We extend this study by using three additional data sets acquired in the South-Western Indian Ocean, the Northern Indian Ocean, and the Northern Pacific Ocean. Our analysis on these data do not well support the previous hypothesis of the geomagnetic paleointensity variation within the CNS. Further, our results indicate that it is of crucial importance to assess the two-dimensional character of the magnetized sources, because it leads to avoid interpreting spurious local effects as paleointensity variations and to derive a reliable geomagnetic paleointensity variation.
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| Academic Significance and Societal Importance of the Research Achievements |
海洋地殻形成の拡大速度から、太平洋ハワイ沖での海上観測での地磁気異常データから推定する古地磁気変動の時間分解能は、大西洋やインド洋での深海観測での地磁気異常データによる時間分解能とほぼ同等であることが確認できた。また、地磁気異常の変化から古地磁気変動の記録を抽出するためには、磁化原因物体の2次元性の吟味と3次元性の影響の除去が必須である。このことから、長期間にわたって地磁気逆転が起きなかった特異な時期である白亜紀スーパークロンにおける古地磁気変動の情報を得るには、太平洋ハワイ沖での複数測線での海上地磁気観測が鍵であり、この情報が地磁気成因の理解を進めるために重要であることが分かった。
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Report
(5 results)
Research Products
(23 results)
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[Presentation] Revisiting the Cretaceous Normal Superchron in the SW Indian Ocean2017
Author(s)
Dyment, J., Y. Gallet, R. Granot, N. Seama, M. Blanc, H. Choe, K. Okino, A. Pasenko, M. Phua, C. Poitou, S. Roth, T. Sato, T. Zhang, C. Hemond, E. Kraus, M. Makuzeni, G. Raifman, V. S. Razafimamonjy, A. Schatz and F. Resseguier
Organizer
American Geophysical Union 2017 Fall Meeting
Related Report
Int'l Joint Research
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