New field, petrographic, geochemical and Rb–Sr/Sm–Nd isotope data are presented from early mafic dykes which intrude the Mesoproterozoic Cape Meredith Complex, West Falkland. The dykes, which have been previously regarded as being Ordovician in age, are seen in the field to cut a suite of lamprophyre sheets. New K–Ar data from biotite separates from two lamprophyres suggest a miminum age of emplacement of ∼520 Ma, confirming previous work. The Rb–Sr and Sm–Nd analyses of the pre-lamprophyre mafic dykes suggests that they were probably intruded during the late Neoproterozoic at ∼600 Ma. This new data has considerable implications for the previously published estimates of the longevity of intracontinental extension events in this part of Gondwana.