Encyclopedia of Astrobiology

2011 Edition
| Editors: Muriel Gargaud, Ricardo Amils, José Cernicharo Quintanilla, Henderson James (Jim) CleavesII, William M. Irvine, Daniele L. Pinti, Michel Viso

Komatiite

  • Nicholas ArndtEmail author
Reference work entry
DOI: https://doi.org/10.1007/978-3-642-11274-4_851

Keywords

Archean volcanic rock, mantle temperature

Definition

Komatiite is a volcanic rock of ultramafic composition. It is distinguished from the more common basaltic magma by a higher content of MgO (>18%) and low contents of most other elements.

Overview

Komatiite is relatively common in Archean greenstone belts, rare in Proterozoic belts, and virtually absent in younger regions. The type area is the 3.5 Ga  Barberton greenstone belt of South Africa where the rock type was first discovered. Examples are now known in most Archean greenstone belts, and komatiitic basalt, the fractionation product of komatiite, occurs in Proterozoic belts of northern Canada. The komatiites of Gorgona Island off the coast of Colombia are the sole well-documented example of Phanerozoic komatiite. The older, 3.5 Ga komatiites have different chemical compositions from younger komatiites, being characterized by high CaO/Al 2O 3 and low Al 2O 3/TiO 2. Important ore deposits of Ni-Cu sulfides are found in...
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References and Further Reading

  1. Arndt N, Lesher MC, Barnes SJ (2008) Komatiite. Cambridge University Press, Cambridge, p 488CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2011

Authors and Affiliations

  1. 1.Maison des Géosciences LGCAUniversité Joseph Fourier, GrenobleSt-Martin d’HèresFrance