Major,minor, and trace element compositions of peridotitic and basaltic komatiites from the precambrian crust of Southern Africa |
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| Authors: | A Günter Herrmann Douglas P Blanchard Larry A Haskin Jeffrey W Jacobs Doris Knake Randy L Korotev Joyce C Brannon |
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| Institution: | (1) Geochemisches Institut der Universität, D-3400 Göttingen, Federal Republic of Germany;(2) The Lunar Science Institute, 3303 NASA Road 1, 77058 Houston, Texas, USA;(3) NASA Johnson Space Center, 77058 Houston, Texas, USA;(4) Lockheed Electronics Corporation, 77058 Houston, Texas, USA;(5) Wilhelm-Raabe-Str. 19, D-3005 Seelze/Hannover, Federal Republic of Germany;(6) Department of Chemistry, University of Wisconsin, 53706 Madison, Wisconsin;(7) NASA Johnson Space Center, 77058 Houston, Texas, USA |
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| Abstract: | Major and trace element compositional data are reported for nine mafic and ultramafic rock samples from the Barberton greenstone belt. Rocks from this province are among the oldest fragments of the Earth's crust ( 3.5 b.y.). The data are consistent with an oceanic crust related origin for these rocks. The high abundances of Ni in these samples make their origin by fractional crystallization of a primitive magma unlikely but are consistent with their generation by partial melting of an upper mantle source. The basaltic samples from the Komati formation can be related by small degrees of partial melting of a primitive upper mantle source to the peridotitic komatiite which probably derived from much more extensive partial melting of a similar source. REE and especially Ni abundances limit the proportion of olivine that is permitted in the residue. |
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