Rb-Sr analyses of 101 samples from the Gaborone Granite Complex and associated rocks suggest that the isotopic systems have undergone at least two periods of disturbance and resetting at c2100 Ma and c. 15-1600 Ma. Only the central rapakivi-granite core has given an unambiguous isochron age of 2616 _+ 36 Ma. This is interpreted as the age of emplacement of the whole complex which is thus considered to be contemporaneous with the widespread Ventersdorp volcanicity. Isotopic disturbance was accompanied in most cases by open-system behaviour so that there has been a bulk loss of Sr relative to Rb and model age calculations yield spuriously low values. The isotopic data are consistent with the interpretation that the surrounding envelope of Kanye Volcanies are genetically related to the rest of the complex and peripheral Lobatse Volcanic Group, Mmathethe Granite and Semarule Syenite were all during the same magmatic event at around 2600 Ma.
