Connectivity between the western and eastern limbs of the Bushveld Complex

The mafic layered rocks of the Bushveld Complex are 6 - 8 km thick and outc rop over an area of 65 000 km(2). The mafic sequences in the western and ea stern limbs are remarkably similar, which suggests that they formed within a single magma chamber. Yet previous interpretations of the Bouguer gravity anomalies negate the possibility that they could be connected at depth. Th ese gravity models are inadequate as they do not consider the isostatic res ponse of this huge mass of mafic rock on the crust. isostatic readjustment caused the base of the crust to be depressed by up to 6 km. In terms of thi s model it becomes possible to construct a gravity profile, consistent with observed data, which includes a 6 - 8 km-thick sequence of mafic rocks a m ere 11 km deep in the crust, connecting the western and eastern limbs of th e Bushveld Complex, where there is no central positive gravity anomaly.