Orthopyroxene + sillimanite predating sapphirine + quartz: A rare case of ultrahigh-temperature metamorphism from the central zone, limpopo complex, South Africa

Georgy A. Belyanin, H. M. Rajesh, Krishnan Sajeev, Dirk D. Van Reenen

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Sapphirine + quartz and orthopyroxene + sillimanite occur in garnet from an Mg-Al granulite from the Central Zone of the Limpopo Complex in South Africa. Textural evidence and a chemical gradient in garnet between the zones preserving the inclusions argue for the formation of sapphirine + quartz after orthopyroxene + sillimanite. Petrological observations, pressure-temperature phase diagrams, and compositional and model proportion results on isopleths indicate the sapphirine + quartz + garnet + orthopyroxene (high-Al) assemblage as the peak metamorphic assemblage (~1050 °C at ~8.5 kbars), whereas orthopyroxene (low-Al) + sillimanite represents the prograde stage (at ca. 900 °C at ~8.5 kbars). Our report of these two diagnostic ultrahigh-temperature mineral assemblages in garnet from an Mg-Al granulite is unique, given the rare occurrence of sapphirine + quartz postdating orthopyroxene + sillimanite assemblage in granulites.

Original languageEnglish
Pages (from-to)1153-1163
Number of pages11
JournalCanadian Mineralogist
Volume50
Issue number5
DOIs
Publication statusPublished - Oct 2012

All Science Journal Classification (ASJC) codes

  • Geochemistry and Petrology

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