• Search Research Projects
  • Search Researchers
  • How to Use
  1. Back to project page

1988 Fiscal Year Final Research Report Summary

Comparative Petrologic Study of Basaltic Rocks from the Kinki and Chubu Districts

Research Project

Project/Area Number 61470050
Research Category

Grant-in-Aid for General Scientific Research (B)

Allocation TypeSingle-year Grants
Research Field 鉱物学(含岩石・鉱床学)
Research InstitutionTOYAMA UNIVERSITY

Principal Investigator

UJIKE Osamu  TOYAMA UNIVERSITY Faculty of Science, 理学部, 助教授 (10176662)

Project Period (FY) 1986 – 1988
KeywordsBasaltic Rocks / Geochemistry / Central Japan / Island Arc / Depth of Subduction Zone / Mantle Material / East Japan Volcanic Zone / サブダクション帯
Research Abstract

The origins of basaltic rocks from the Kinki and Chubu districts were studied through extensive microprobe analysis of the phenocrysts and the whole-rock geochemistry. The studied rocks are alkalic, olivine tholeiitic and calc-alcalic basalts to andesites erupted in central Japan where the depth of the subducting Pacific plate (subduction zone) ranges from -150 to -400 km. Rocks from volcanoes beneath which the subduction zone is <-250 km deep are typical island-arc basalts and their derivatives in mineralogy and chemistry. On the other hand, despite their distribution in an island arc system, rocks from places beneath which the subduction zone is >-250 km deep show a magmatic affinity unlike the arc type: chemical compositions of the phenocrysts (olivine, plagioclase and clinopyroxene) are characteristic to non-arc settings; and the whole-rock analyses of the basalts do not show marked depletion of Ta, Hf and Ti relative to Th, Ce and Sm. These basaltic rocks formed probably from a so … More urce which has generated the Neogene alkalic volcanic rocks bearing a within-plate alkalic basalt affinity in west Japan, by greater degrees of melting at shallower depths. At places where the depth of the subduction zone is -250 km, olivine tholeiitic rocks with a within-plate basalt affinity erupted at -2 Ma, while rocks with an island-arc basalt affinity have been erupted at <1 Ma.
A batch of mantle material, potentially a source of the Neogene alkalic volcanic rocks in west Japan, is likely to have emplaced beneath the Ryohaku Mts. at the back-arc side of the East Japan Volcanic Zone. It is probable that a change in motion of the Philippine Sea plate at -3 Macaused the sudden drift of the non-arc type magma source from the uppermost mantle beneath the Ryohaku Mts. to that beneath the Norikura Volcanic Chain. The K-Ar age data suggest that at -1.5 Ma, the magma source was drifted westward back to the uppermost mantle beneath the Ryohaku Mts. by a steady flow of mantle convection beneath the East Japan Arc System. Less

  • Research Products

    (8 results)

All Other

All Publications (8 results)

  • [Publications] 氏家治: 岩石鉱物鉱床学会誌. 84. (1989)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] UJIKE,Osamu: Geochim.Cosmochim.Acta. 52. 2037-2046 (1988)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] UJIKE,Osamu: Can.J.Earth Sci.24. 2551-2567 (1987)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] UJIKE,Osamu: J.Jpn.Assoc.Miner. Petr.Econ.Geol.82. 245-256 (1987)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] UJIKE, Osamu: "Ueno basaltic rocks -Products of a non-arc type magmatism-." J. Jpn. Assoc. Miner. Petr. Econ. Geol.84. (1989)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] UJIKE, Osamu: "Probable mineralogic control on the mantle metasomatic fluid composition beneath the Northeast Japan arc." Geochim. Cosmochim. Acta. 52. 2037-2046 (1988)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] UJIKE, Osamu: "Geochemistry and origin of Archean felsic metavolcanic rocks, Central Noranda Area, Quebec, Canada." Can. J. Earth Sci.24. 2551-2567 (1987)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] UJIKE, Osamu: "Mantle metasomatic enrichment in LILE of basalt magma sources beneath the NE Japan arc, as indicated by the LILE/Y-Zr/Y plots." J. Jpn. Assoc. Miner. Petr. Econ. Geol.82. 245-256 (1987)

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

URL: 

Published: 1990-03-20  

Information User Guide FAQ News Terms of Use Attribution of KAKENHI

Powered by NII kakenhi