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1998 Fiscal Year Final Research Report Summary

Geodynamics of generation of oceanic crust-an example of the Oman ophiolite

Research Project

Project/Area Number 09041101
Research Category

Grant-in-Aid for international Scientific Research

Allocation TypeSingle-year Grants
SectionField Research
Research Field Geology
Research InstitutionNiigata University

Principal Investigator

MIYASHITA Sumio  Niigata Univ., Faculty of Science, Professor, 理学部, 教授 (60200169)

Co-Investigator(Kenkyū-buntansha) TAKAZAWA Eiichi  Niigata Univ., Faculty of Science, Lecturer, 理学部, 講師 (80222082)
ISHIKAWA Tsuyoshi  Shizuoka Univ., Faculty of Science, Lecturer, 理学部, 講師 (30270979)
UMINO Susumu  Shizuoka Univ., Faculty of Science, Associate Professor, 理学部, 助教授 (30192511)
川幡 穂高  地質調査所, 海洋地質部, 主任研究官
ARAI Shoji  Kanazawa Univ., Faculty of Science, Professor, 理学部, 教授 (20107684)
MASUDA Toshiaki  Shizuoka Univ., Faculty of Science, Professor (20107684)
Project Period (FY) 1997 – 1998
Keywordsophiolite / oceanic crust / Oman / mantle / layered gabbro
Research Abstract

The results obtained from this research project are summarized for each group.
Mantle group clarified an interaction between melt and mantle in the mantle-crust transition zone. Also they round the interaction was quite hetrogenous palce to place. Analyses of spinel using river sand show that the mantle peridotites of the Oman ophiolite are highly depleted compared to oceanic mantle, suggesting that signiricant modification or the mantle peridotite occured during later island arc stage.
Gabbro group round two series of gabbros previously regarded as successive complex, which were formed at advancing and dying magma chambers beneath ocean ridges, respectively. This is explained by overlapping ocean ridges where propagation and retreating or ridges appeared. The central part of ridge segment where thick Moho transition zone occurs was determined through regional detailed geological mapping in the northern Oman ophiolite. From the central part to the tip or ridge segmenl, mineral compositions or layered gabbro varies systematically from less evolved to more evolved compositions.
Upper crust group measured direction and thickness of dikes from extensive area in the northern Oman ophiolite. They found that the direction of dikes varies for each several km length, indicating the smallest order of segmentation of ocean ridges. The thickness of dikes increases from the central part to tip of the ridge segment in more large scale which is presumed from the petrological features of gabbro and mantle peridotite.
Structural group found two different mineral lineations on foliation plane in the metamorphic sole beneath the Oman ophiolite. Also they clarified that the degree of preferred orientation is quite various even in one outcrop.

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] Umino, S.and Horio, A: "Multistage magma mixing revcaled inphenocryst zoning of the Yunokuchi Pumice, Akagi Volcano, Japan." Journal of Petrology. 39. 101-124 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 宮下純夫・松尾重明: "MORBか沈み込み帯火成活動か-麻木・吉田(1998) : 徳島県南東部の四万十帯北帯に分布する沈み込み帯型緑色岩への討論" 岩石鉱物鉱床学会誌. 93. 347-351 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Miyashita, S.et al.: "TheNipesotsu Greenstone complex with special referrences to the lateralvariation of green-stone complexes in the northern Hidka zone, Hokkaido, Japan" Jour.Geol.Soc.Japan. 印刷中.

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Arai, S.et al.: "Concentrationof incompatible elements in oceanic mantle : Effect of melt/wall interactionin stagnant or failed conduits within peridotite" Geochim.Cosmochim.Acta. 61. 671-675 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Arai, S.: "Control of wall-rock composition on the formation of podiform chromitites as a result of magma/peridotite interaction." Resource Geol.47. 177-187 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Kawahata, H.et al: "Sulfate in plagiogranites from the Troodos ophiolite, Cyprus." Geochem.Jour.31. 119-124 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Umino, S.and Horio, A.: "Multistage magma mixing revealed inphenocryst zoning of the Yunokuchi Pumice, Akagi Volcano, Japan." Journal of Petrology. 39. 101-124 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Miyashita, S.and Matsuo, S.: "MORB of subduction zone magmatism : Discussion for the paperby Asaki and Yoshida (1998)" J.Min.Petr.Econ.Geol. 93. 347-351

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Miyashita, S.et al.: "The Nipesotsu Greenstone complex with special referrences to the lateralvariation of greenstone complexes in the northern Hidka zone, Hokkaido, Japan" Jour.Geol.Soc.Japan. (in press). (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Arai, S.et al.: "Concentrationof incompatible elements in oceanic mantle : Effect of melt/wall interactionin stagnant or failed conduits within peridotite" Geochim. Cosmochim.Acta. 61. 671-675 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Arai, S.: "Control of wall-rock composition on the formation of podiform chromitites as a result of magma/peridotite interaction." Resource Geol.47. 177-187 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Kawahata, H.et al.: "Sulfate in plagiogranites from the Troodos ophiolite, Cyprus." Geohem.Jour.31. 119-124 (1997)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1999-12-08  

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