We present LA-ICPMS U-Pb zircon ages and field data from the rift-related, Cryogenian-aged Toekems Sub-basin in the south-western Welwitschia Inlier on the southern margin of the Congo Craton in the Damara Belt (Northern Margin Zone), Namibia. The Toekems Sub-basin comprises a wedge up to 730m-thick of dominantly clastic sediments between Palaeoproterozoic basement and the Cryogenian Abenab Subgroup. The base of the succession is a distinct coarsening upward breccia that contains entirely basement clasts. The overlying strata consist of mixed polymictic conglomerates, debris flow diamictites, tuffs, volcaniclastic sandstone, siltstone, and minor carbonates. A pegmatite cross-cutting the basal breccia has yielded a mean weighted average 206Pb/ 238U age of 763±5Ma. This age statistically overlaps the nearby 756±2Ma Oas Syenite and 760±1Ma ash bed in the Ombombo Subgroup to the north and is somewhat older than the ca. 746Ma Naauwpoort Volcanics, which underlie the glacigenic Chuos Formation in the Summas Mountains to the south. This indicates that initial sedimentation in the Toekems Sub-basin began prior to 763Ma. However, the presence of laminae-deforming lonestones, iron-formation and the stratigraphic position relative to the overlying Rasthof cap carbonate suggest that most of the succession is glacially-influenced, and hence correlates with the Chuos Formation. These results imply a significant disconformity beneath the Naauwpoort Volcanics and suggest multi-phase rifting during the breakup of south-western Congo Craton from Rodinia.