Coexistence of jadeite and quartz in garnet of the Sanbagawa metapelite from the Asemi-gawa region, central Shikoku, Japan

Tomoki Taguchi, Masaki Enami

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Coexistence of jadeite (Jd92) and quartz was newly found in an inner segment of a composite-zoned garnet from a metapelite in the southern albite-biotite zone of the Asemi-gawa region, Sanbagawa belt in central Shikoku, Japan. The assemblage of jadeite + quartz in garnet gives a minimum metamorphic pressure of 1.4-1.9GPa at 500-700 °C, which was significantly higher than that previously proposed for epidote-amphibolite facies conditions in the albite-biotite zone. Garnet includes quartz retaining high residual pressure (Δω1 values up to 11.7 cm-1), which is comparable to the residual pressure reported in eclogite and metapelite within the eclogite unit in central Shikoku. These results imply that (1) the inner segment of the composite-zoned garnet records prograde recrystallization under high-pressure blueschist to eclogite facies conditions and (2) at least a part of the southern albite-biotite zone of the Asemi-gawa region recrystallized under higher pressure conditions prior to the regional metamorphism from the greenschist to epidote-amphibolite facies that formed the regional thermal structure of the Sanbagawa belt of central Shikoku.

Original languageEnglish
Pages (from-to)169-176
Number of pages8
JournalJournal of Mineralogical and Petrological Sciences
Volume109
Issue number4
DOIs
Publication statusPublished - 2014
Externally publishedYes

Keywords

  • Eclogite facies metamorphism
  • Jadeite + quartz
  • Metapelite
  • Residual pressure
  • Sanbagawa belt

ASJC Scopus subject areas

  • Geophysics
  • Geology

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