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2001 Fiscal Year Final Research Report Summary

Quantitative modeling unifying magmatism and metamorphism

Research Project

Project/Area Number 11440159
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field Petrology/Mineralogy/Science of ore deposit
Research InstitutionThe University of Tokyo

Principal Investigator

IWAMORI Hikaru  Graduate School of Science, The University of Tokyo, Assoc. Prof., 大学院・理学系研究科, 助教授 (80221795)

Co-Investigator(Kenkyū-buntansha) TORIUMI Mitsuhiro  Graduate School of Frontier Sciences, The University of Tokyo, Prof., 大学院・新領域創成化学研究科, 教授 (10013757)
Project Period (FY) 1999 – 2001
Keywordssubduction zone / magmatism / metamorphism / numerical modeling / melting / metamorphic belt / seismic structure
Research Abstract

Recent knowledge concerning the phase relationships of hydrous peridotitic and basaltic systems allows us to model fluid generation and migration in subduction zones. Such numerical model has been developed in this study. The results have been compared with geological and seismic observations. The comparisons suggest that the thermal structure (determined by age and subduction velocity) of the subducting plate strongly controls the distribution of the aqueous fluids and melts in subduction zones through the position of the dehydration reactions, and that water subducted into the mantle is expelled at shallower than 200 km in most of the subduction zones in the world.
By constrast, as a consequence of the hot plate, including ridge subduction. pressure-temperature field appropriate for both high-and low-P/T regional metamorphism, together with a large amount of granitic magmatism, are produced simultaneously in the trench-foreacr system. The result supports the concept of paired metamorphic belts.
Deformation and P-T conditions of the Cretaceous Ryoke-Sambagawa metamorphic belts have been analyzed based on recent numerical modeling of plastic flow at convergent plate boundaries. The analyzes suggest that a three-dimensional corner flow in the forearc wedge associated with moderate obliquity (more than 45 degrees for the angle between the subduction direction and the trench) can explain the observed prolate strain. Based on the analyzes, the contemporaneous Ryoke (low *P/T*) - Sambagawa (high-*P/T*) metamorphic belts are suggested to have been formed within a single trehch-forearc system by a series of the events, not by accidental amalgamation of two distinct terranes, supporting the concept of a 'paried metamorphic belts'. The constrasting low- and high-*P/T* metamorphic conditions are demonstrated to be simultaneously achieved in the forearc region with the dynamic flow associated with ridge subduction, where a large temperature gradient is produced.

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] H.Iwamori, D.Zhao: "Melting and seismic structure beneath the northeast Japan arc"Geophys. Res. Lett.. 27. 425-428 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] D.Zhao, K.Asamori, H.Iwamori: "Seismic structure and magmatism of the young Kyushu subduction zone"Geophys. Res. Lett.. 27. 2057-2060 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] H.Iwamori: "Deep subduction of H20 and deflection of volcanic chain towards backarc near triple junction due to lower temperature"Earth Planet. Sci. Lett.. 181. 41-46 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] H.Iwamori: "Thermal effects of ridge subduction and its implicatins for the origin of granitic batholith and paired metamorphic belts"Earth Planet. Sci. Lett.. 181. 131-144 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] H.Iwamori: "Transportation of H20 and melting beneath the Japan arcs"Bull. Earthq. Res. Inst.. 76. 377-389 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] H.Iwamori: "Some remarks on deformation and P-T conditions of the Cretaceous regional metamorphic belts in southwest Japan"Earth Planet. Sci. Lett.. (in press).

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] H. Iwamori and D. Zhao: "Melting and seismic structure beneath the northeast Japan arc"Gedphys. Res. Lett.. 27. 425-428 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] D. Zhao, K. Asamori, and H. Iwamori: "Seismic structure and magmatism of the young Kyushu subduction zone"Gedphys. Res. Lett.. 27. 2057-2060 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] H. Iwamori: "Deep subduction of H20 and deflection of volcanic chain towards backarc near tripple junction due to lower temperature"Earth Planet. Sci. Lett.. 181. 41-46 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] H. Iwamori: "Thermal effects of ridge subduction and its implications for the origin of granitic batholith and paired metamorphic belts"Earth Planet. Sci. Lett.. 181. 131-144 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] H. Iwamori: "Transportation of H20 and melting beneath the Japan arcs"Bull. Earthq. Res. Inst.. 76. 377-389 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] H. Iwamori: "Some remarks on deformation and P-T conditions of the Cretaceous regional metamorphic belts in southwest Japan: reply to comment by M. Brown on "Thermal effects of ridge subduction and its implications for the origin of granitic batholith and paired"Earth Planet. Sci. Lett.. (in press).

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

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Published: 2003-09-17  

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