Chemostratigraphic correlation of carbonate successions in the Gariep and Saldania Belts, Namibia and South Africa

Inter- and intrabasinal correlation of Neoproterozoic carbonate successions and associated glaciogenic deposits from the Pan-African Gariep Belt and the Kango inlier in the Saldania Belt (Namibia and South Africa) is proposed on the basis of new delta(13)C(Carb) and Sr-87/(86)Sri data. Highly positive delta(13)C(Carb) values (as much as + 8.65parts per thousand) and low Sr-87/(SrI)-Sr-86 ratios (0.7071-0.7077) were obtained on carbonate successions of the Hilda Subgroup between an older and a younger diamictite in the Port Nolloth Group (Gariep Belt). These results are in agreement with data elsewhere that suggest deposition between the global similar to750 Ma Sturtian and similar to 580 Ma Marinoan glaciations. Considerably lower, positive delta(13)C(Carb) values (up to + 1.01parts per thousand) and higher Sr-87 /Sr-86(I) ratios (0.7082-0.7085) mark the carbonates (Bloeddrif Member, Holgat Formation) on top of the Numees Formation diamictite and support a correlation of this diamictite with the Marinoan glaciation. In the southern extension of the Gariep Belt, correlation of the Widouw Formation limestone (Gifberg Group) with the Bloeddrif Member carbonates is proposed based on similar isotopic characteristics. In the Kango inlier of the Saldania Belt, two carbonate-bearing members exist in the Matjies River Formation. The lower one of these two (Nooitgedacht Member) compares well with the Hilda Subgroup, whereas the upper one (Kombuis Member) shows strong similarities to the Bloeddrif Member carbonates. This implies that all younger stratigraphic units of the Kango inlier are not correlatives of the Port Nolloth Group, as previously assumed, but syn- to post-orogenic with respect to the 540-580 Ma Pan-African orogeny.