Unroofing the Kalahari craton: Provenance data from Neoproterozoic to Paleozoic successions

The formation of the Kalahari craton ended with massive Mesoproterozoic tectonic processes, but hosts the history of the craton evolution since the Paleoarchean. We sampled more than 50 Neoproterozoic to Devonian sedimentary formations from the western and southern margin of the craton to decipher a typical Kalahari/Kaapvaal provenance. Major peaks for detrital zircons revealed an overwhelming abundance of Mesoproterozoic zircons (1.4 ñ 1.0 Ga) reflecting the Natal and Namaqua orogenies with multiple collisional phases. Zircons older than 1.8 Ga were not found in the samples. Other major peaks reflect tectonic processes during the Ediacara and Cambrian. The mostly immature Neoproterozoic rocks host partly an active margin provenance but no definite arc signature. Detrital zircon data, whole rock Pb and Nd isotope analyses resemble the existent data from Patagonia, and Antarctica fragments. We propose therefore, that an exotic block (Patagonia) represented the actual Neoproterozoic arc terrane and rifted away during the Paleozoic. The immature Devonian Bokkeveld Group hosts surprisingly Silurian to Lower Devonian zircons related to magmatic activity at the western and southwestern margin of the Kalahari craton, so far understood to be a passive margin. Massive pyroclastic activity is recorded only in Eastern Argentina, associated with a formerly Neoproterozoic Hirnantian glacial diamictite (now dated as 485 Ma) and quartz-arenites. The origin of this magmatic event is unknown. Our study demonstrates that detrital zircon data should be treated carefully if used for understanding a cratonic fingerprintî as characterising magmatic events might not be reflected at the margins of a craton.