Abstract
MESOZOIC igneous activity in South-West Africa is shown as lava plateaux and dyke swarms of basaltic composition and as a group of central volcanic complexes representing a highly variable range of rocks1. The Paresis complex (20° 15′ S., 15° 42′ E.) is one of the latter and is made up of a consanguineous suite of syenites, bostonites, rhyolites and associated foyaitic rocks, as well as minor basalts and gabbros. From structural and geochemical evidence Siedner2,3 concluded that the basaltic rocks of Paresis represent locally preserved remnants of the regional Stormberg volcanics coeval with, but genetically un related to, the central felsic suite. The age of Paresis is thus significant because it dates both the complex and the regional volcanism. The only other published chronological datum on Mesozoic igneous centres in South-West Africa is a potassium–argon age of 190±8×106 yr on biotite from the Klein Spitzkop granite4.
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