Finding of talc- and kyanite-bearing amphibolite from the Paleoproterozoic Usagaran Belt, Tanzania

Keiko Mori, Tatsuki Tsujimori, Nelson Boniface

Research output: Contribution to journalLetterpeer-review

2 Citations (Scopus)

Abstract

We report a newly discovered assemblage of talc-kyanite in an amphibolite from the Isimani Suite of the Paleoproterozoic Usagaran Belt, central Tanzania. The amphibolite is characterized by the mineral assemblage of clinoamphibole, kyanite, talc with minor rutile, quartz, dolomite, and rare barite. The high Fe3+/(Fe3+ + Fe2+) ratio (0.48-0.80) of clinoamphibole and the presence of sulfate (barite) indicate a very-high oxidation state during metamorphism. P-T pseudosection modelling predicts that the studied talc- and kyanite-bearing amphibolites formed at high-pressure conditions (P > 1.0 GPa). Moreover, the modelling suggests formation of talc + kyanite + clinoamphibole at a highly oxidizing condition with CO2 fluid. This talc-kyanite association provides an index of high-pressure metamorphism of the Usagaran Belt and marks the oldest record of the talc- kyanite association in regional metamorphism in the Earth's history.

Original languageEnglish
Pages (from-to)316-321
Number of pages6
JournalJournal of Mineralogical and Petrological Sciences
Volume113
Issue number6
DOIs
Publication statusPublished - 2018 Dec 1

Keywords

  • Amphibolite
  • High-pressure metamorphism
  • Kyanite
  • Talc
  • Tanzania
  • Usagaran Belt

ASJC Scopus subject areas

  • Geophysics
  • Geology

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