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Alkali basaltic-lamprophyric dykes intrude Precambrian gneisses in the Schirmacher Oasis, Queen Maud Land, East Antarctica. Rb-Sr and sm-Nd isotopic data on two lamprophyre dykes are reported from the Schirmacher Oasis. The lamprophyre dykes have given Rb-Sr biotite/whole rock isochron age of 439 +/- 10 Ma (2 sigma). Large variations in epsilon Sr and epsilon Nd indicate higher degree of crustal assimilation. Higher epsilon Sr (+54 to +72) and lower epsilon Nd (-7 to -13) of these dykes also suggest that the source was contaminated by older crust. Biotite/whole rock Rb-Sr isotope data on lamprophyre dykes show that the terrain was affected by thermal event during early Paleozoic which is correlated with the end of Pan-African orogeny.