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Spreading process of the Mariana Trough

Research Project

Project/Area Number 12440116
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field 固体地球物理学
Research InstitutionKobe University

Principal Investigator

SEAMA Nobukazu  Kobe University, Research Center for Inland Seas, Associate Professor, 内海域機能教育研究センター, 助教授 (30270862)

Co-Investigator(Kenkyū-buntansha) ISEZAKI Nobuhiro  Chiba University, Department of Earth Sciences, Professor, 理学部, 教授 (60107943)
HYODO Masayuki  Kobe University, Research Center for Inland Seas, Professor, 内海域機能教育研究センター, 教授 (60183919)
YAMAZAKI Toshitsugu  AIST, Institute for Marine Resources and Environment, Group Leader, 海洋資源環境研究部門, 研究グループ長
Project Period (FY) 2000 – 2002
Project Status Completed (Fiscal Year 2002)
Budget Amount *help
¥15,200,000 (Direct Cost: ¥15,200,000)
Fiscal Year 2002: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2001: ¥7,500,000 (Direct Cost: ¥7,500,000)
Fiscal Year 2000: ¥6,200,000 (Direct Cost: ¥6,200,000)
KeywordsMariana Trough / Back-arc Basin / Sea-floor Spreading / Ocean Bottom Electro-Magnetometers
Research Abstract

The Mariana Trough is a typical intra-oceanic back-arc basin that shows a variety of features. We have compiled extensive surface geophysical data (bathymetry, magnetic and gravity) of the Mariana Trough, which were collected during several Japanese cruises over the last few years. Topographic features and the mantle Bouguer anomaly (MBA) reveal distinct differences between regions. The north of 22N shows extremely low MBA indicating an incipient rifting. The central region between 21N and 14N shows characteristic slow-spreading features; existence of median valley neovolcanic zone and "Bull's eyes" MBA along the axes. The south of 14N shows an EPR type axial relief morphology and lower MBA than that in the central. Tectonic evolution can be inferred from the direction of spreading fabric, the trace of non-transform offsets, and by crustal ages identified by vector geomagnetic anomaly field. The crustal ages indicate that the seafloor spreading started at 4Ma, 6Ma and 3Ma at the northern end, the central, and the southern end, respectively. The spreading rates are generally slow (~20 mm/yr) in the northern and central areas, while they are fast (~35 mm/yr) in the south. Spreading axis directions have gradually changed by 15 degrees clockwise with age in the north of 17.5N, while they occurred at 3.5-3.0Ma from N35W to N5W just south of 17.5N. On the other hand, they are relatively constant in the southern end.
We have developed a new type of ocean bottom electro-magnetometer (OBEM), which is small and easy to handle with Filloux-type electrodes. Preliminary results of an OBEM observation for one year in the Mariana region suggest that very conductive zone (about 70km in depth) below the Marianas island arc and low conductivity zone with thickness of a few ten km beneath the Mariana Trough.

Report

(4 results)
  • 2002 Annual Research Report   Final Research Report Summary
  • 2001 Annual Research Report
  • 2000 Annual Research Report
  • Research Products

    (13 results)

All Other

All Publications (13 results)

  • [Publications] Mitsuzawa, K.: "Preliminary report of Deep-Tow/Yokosuka Cruise at hydrothermal areas in the Mid and Southern Mariana"JAMSTEC J.Deep Sea Res.. 17. 73-87 (2000)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] Masuda, H.: "Bathymetry and Hydrothermal activities in the southern Mariana Trough-reconnaissance results of YK-99-11"JAMSTEC J.Deep Sea Res.. 18. 265-273 (2001)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] Goto, T.: "Geophysical Experiments in the Mariana Region : Report of the YK01-11 cruise"InterRidge News. 11. 22-24 (2002)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] Seama, N.: "Preliminary Report of KR02-14 Kairei cruise"JAMSTEC J.Deep Sea Res.. 22. 89-106 (2003)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] Mitsuzawa, K. et al.: "Preliminary report of Deep-Tow/Yokosuka Cruise at hydrothermal areas in the Mid and Southern Mariana"JAMSTEC J. Deep Sea Res.. 17. 73-87 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] Masuda, H. et al.: "Bathymetry and Hydrothermal activities in the southern Mariana Trough - reconnaissance results of YK-99-11"JAMSTEC J. Deep Sea Res.. 18. 265-273 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] Goto, T. et al.: "Geophysical Experiments in the Mariana Region: Report of the YK01-11 cruise"InterRidge News. 11. 22-24 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] Seama, N. et al.: "Preliminary Report of KR02-14 Kairei cruise"JAMSTEC J. Deep Sea Res.. 22. 89-106 (2003)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] Goto, T.: "Geophysical Experiments in the Mariana Region : Report of the YKO1-11 cruise"InterRidge News. 11. 22-24 (2002)

    • Related Report
      2002 Annual Research Report
  • [Publications] Seama, N.: "Preliminary Report of KR02-14 Kairei cruise"JAMSTEC J. Deep Sea Res.. 22. 89-106 (2003)

    • Related Report
      2002 Annual Research Report
  • [Publications] Masuda, H.: "Bathymetry and Hydrothermal activities in the southern Mariana Trough -reconnaissance results of YK-99-11"JAMSTEC J. Deep Sea Res.. 10. 265-273 (2001)

    • Related Report
      2001 Annual Research Report
  • [Publications] Baba, K.: "A new technique for the incorporation of seafloor topography in electromagnetic modeling"Geophysical Journal International. (in press). (2002)

    • Related Report
      2001 Annual Research Report
  • [Publications] Mitsuzawa,K: "Preliminary report of Deep-Tow/Yokosuka Cruise at hydrothermal areas in the Mid and Southern Mariana"JAMSTEC J.Deep Sea Res.. 17. 73-87 (2000)

    • Related Report
      2000 Annual Research Report

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Published: 2000-04-01   Modified: 2016-04-21  

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