Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Shimizu, K. Articles by Maruyama, S. Search for Related Content GeoRef GeoRef Citation

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

¹ Pheasant Memorial Laboratory, Institute for Study of the Earth's Interior, Okayama University at Misasa, Tottori 682-0193, Japan
² Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo, 152-8551, Japan

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.

Key Words: Belingwe • komatiite • garnet • xenocryst • crustal assimilation • continental flood basalt

This article has been cited by other articles:

				K. SHIMIZU, E. NAKAMURA, and S. MARUYAMA The Geochemistry of Ultramafic to Mafic Volcanics from the Belingwe Greenstone Belt, Zimbabwe: Magmatism in an Archean Continental Large Igneous Province J. Petrology, November 1, 2005; 46(11): 2367 - 2394. [Abstract] [Full Text] [PDF]