Ultramafic rocks in the centre of the Vredefort structure (South Africa): geochemical affinity to Bushveld rocks

The geochemistry and mineral chemistry of ultramafic rocks in the centre of the Vredefort structure have been reinterpreted. A detailed examination of previously published major element, trace and REE analyses as well as mineral analyses strongly suggests a magmatic origin in contrast to previously postulated tectonic emplacement of mantle material. A strong geochemical affinity to ultramafic rocks from the Bushveld Complex is evident. The magmatic nature of the ultramafic rocks in the centre of the Vredefort structure has implications for the discussion of the metamorphic history of the Vredefprt structure which shows evidence of unusually high, and as yet not satisfactorily explained, geothermal gradients during peak metamorphism.