Contributions to Mineralogy and Petrology

, Volume 95, Issue 3, pp 376–383 | Cite as

Reduced sapphirine granulite xenoliths from the Lace Kimberlite, South Africa; implications for the deep structure of the Kaapvaal Craton

  • J. B. Dawson
  • J. V. Smith
Article
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Abstract

Sapphirine-bearing granulites, together with sapphirine-free granulites and eclogites, occur as xenoliths in the kimberlite of the Lace diatreme that penetrates the Kaapvaal craton, S. Africa. Absence of (calculated) Fe3+ in sapphirine, garnet and sillimanite, together with presence of graphite and sulphides, suggests highly reducing conditions of metamorphism. Chemical considerations and comparisons with experimental investigations suggest metamorphism of a sedimentary (?chlorite-montmorillonite) protolith at 900–1000° C and > 10 Kb; high Cr in the assemblage may point to a basic/ultrabasic precursor. The xenoliths indicate the presence of a very-high-grade granulite terrain, possibly similar to Enderby Land (Antarctica), beneath the Kaapval craton.

Keywords

Graphite Sulphide Experimental Investigation Mineral Resource Deep Structure 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
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Copyright information

© Springer-Verlag 1987

Authors and Affiliations

  • J. B. Dawson
    • 1
  • J. V. Smith
    • 2
  1. 1.Department of GeologyUniversity of SheffieldSheffieldUK
  2. 2.Department of Geophysical SciencesUniversity of ChicagoChicagoUSA

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