Discovery of Archean continental and mantle fragments inferred from xenocrysts in komatiites, the Belingwe greenstone belt, Zimbabwe

Kenji Shimizu, Eizo Nakamura, Katsura Kobayashi, Shigenori Maruyama

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Controversy exists as to whether the 2.7 Ga Belingwe greenstone belt, Zimbabwe, is autochthonous or allochthonous. In this study we report direct evidence for an autochthonous continental setting for the Belingwe greenstone belt. Garnet and clinopyroxene xenocrysts were discovered in the fresh ultramafic komatiites. Major and trace element compositions of these xenocrysts suggest that they originated from mafic lower crust, presumably garnet granulite in composition, at a low temperature of ∼600 or ∼700 °C. Furthermore, in a komatiitic basalt sample, we have discovered orthopyroxene and clinopyroxene xenocrysts that may have originated from lithospheric mantle beneath the continental margin. Discoveries of these xenocrysts indicate that the komatiite magma was transported to the surface and quenched rapidly enough to prevent the complete melting of continental fragments.

Original languageEnglish
Pages (from-to)285-288
Number of pages4
JournalGeology
Volume32
Issue number4
DOIs
Publication statusPublished - Apr 1 2004

Keywords

  • Belingwe
  • Continental flood basalt
  • Crustal assimilation
  • Garnet
  • Komatiite
  • Xenocryst

ASJC Scopus subject areas

  • Geology

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