Boron isotope compositions of antigorite-grade serpentinites in the Itoigawa-Omi area of the Hida-Gaien Belt, Japan

Chinatsu Yamada, Tatsuki Tsujimori, Qing Chang, Jun Ichi Kimura

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

The antigorite-grade serpentinite and Late Paleozoic high-pressure schists are main components of a serpentinite-matrix melange in the Itoigawa-Omi area, Hida-Gaien Belt, Japan. Based on the petrologic characteristics of the high-pressure schists, the melange is divided into two units, namely an šeeclogitic unitšf and a šenon-eclogitic unitšf. Our preliminary in-situ boron isotope analyses of five serpentinites using a laser-ablation multiple-collector inductively-coupled-plasma mass spectrometry (LA-MC-ICPMS) found a systematic difference of boron isotopic trends among the two units in the same melange. The šeeclogitic unitšf serpentinites from Yunotani and Kotagi-gawa are characterized by lower δ11B value (mostly lower than +10‰), whereas the non-eclogitic unit serpentinite from Omi-gawa is higher than +1‰. Although the δ11B value of <0‰ was not measured from the eclogitic unit serpentinites, the relatively low δ11B values of <+10‰might have recorded the signature of fluids released from deep subducted dehydrating slab. In contrast, the non-eclogitic unit serpentinite might have been affected by fluids released from shallower portion. Our new data confirmed the potential sensitivity of the boron isotope signature of serpentinites reflecting variation of high-pressure metamorphism.

Original languageEnglish
Pages (from-to)290-295
Number of pages6
JournalJournal of Mineralogical and Petrological Sciences
Volume114
Issue number6
DOIs
Publication statusPublished - 2019 Jan 1

Keywords

  • Antigorite serpentinite
  • Boron isotope
  • Hida-Gaien Belt
  • Itoigawa-Omi area

ASJC Scopus subject areas

  • Geophysics
  • Geology

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