Palaeomagnetic samples were collected from 2 dykes belonging to the Gannakouriep dyke swarm, one located in the centre of the Richtersveld subprovince (8215), the other further S in the Steinkopf Domain (8212), where it has been clearly overprinted by a later metamorphic episode. Detailed thermal and A.F. demagnetization indicate that the primary remanence has been extensively overprinted in both dykes. The 40Ar/39Ar step-heating analyses of a whole-rock sample of the 8212 yield a plateau spectrum with an integrated age of 542 + or - 4 Ma; whereas, the 40Ar/39Ar spectrum for a whole-rock sample of 8215 yields a saddle-shaped spectrum with the minimum at approx 400 Ma.-from Authors