A ca. 200Ma hiatus between the Lower and Upper Transvaal Groups of southern Africa: SHRIMP U–Pb detrital zircon evidence from the Segwagwa Group, Botswana: Implications for Palaeoproterozoic glaciations

Meso-Archaean and Palaeo-Proterozoic sedimentary sequence stratigraphy of the Kaapvaal Craton

“…uplift -rifting -thermal subsidence; uplift and rifting is related to essentially volcanic and immature sandy fluvial deposition, with thermal subsidence being inferred to have accommodated the two maj or epeiric marine (argillaceous) successions and references therein). Age data on the Pretoria-Segwagwa succession is limited: (1) 2316±7 Ma (Re-Os; Hannah et al, 2004) at the base of the groups; (2) detrital z ircons within the Timeball Hill sandstones, Daspoort and Magaliesberg arenites, respectively, at 2250±14/ 15 Ma, 2236±13 Ma and 2193±20 Ma, provide maximum ages for those units (Mapeo et al, 2006; similar data given by Dorland et al, 2004); (3) emplacement date for the Bushveld Complex (2058±0.8 Ma; Buick et al, 2001), which intrudes largely above the Magaliesberg Formation, provides a minimum age for the groups, although a deformational event separates temporally the underlying sedimentary from the intrusive igneous rocks (Bumby et al, 1998) (Fig. 17).…”

The Kaapvaal Craton, South Africa: no evidence for a supercontinental affinity prior to 2.0 Ga?

“…Maximum age for protobasinal rocks of c. 2.68 Ga (Olsson et al in press) is speculative. Age data for Pretoria Group sandstones (shown in brackets; Mapeo et al 2006) reflect detrital zircons and thus represent maximum depositional ages for sampled sandstones; age at base of Pretoria Group (shown with *) from Hannah et al (2004); remaining age data from references in Eriksson et al (2001).…”

“…A major flood basalt (Hekpoort-Tsatsu-Ongeluk Fm's., respectively in TB, KB, GB) is dated in the GB at 2222±13 Ma (Pb-Pb; Cornell et al 1996). The base of the Pretoria Group is dated at 2316±7 Ma (Re-Os; Hannah et al 2004); detrital zircon dating within successively higher sandstone units varies from maximum sedimentation ages of 2250±14/15 Ma near the base, to 2236±13 Ma in the medial Daspoort sandstones to 2193±20 Ma in the Magaliesberg Formation, in a stratigraphically high position (Figure 1) (Mapeo et al 2006; similar detrital age data are given by Dorland et al 2004). Although the emplacement age for the Bushveld Complex reflects a minimum age for the Pretoria Group of 2058±0.8 Ma (Buick et al 2001), a time gap between the end of Transvaal sedimentation and Bushveld magmatism is indicated by regional compressive deformation of the sedimentary succession .…”

“…The uppermost mixed clastic-chemical sediments are related to final withdrawal of the epi-continental sea from NE to SW (e.g., Eriksson et al 2005). Deposition of the localised Duitschland Formation (far NE of the TB only) probably occurred within a depositional hiatus of possibly 80 My (possibly up to c. 200 My according to Mapeo et al 2006) separating Chuniespoort and Pretoria Groups (and equivalents in the other two basins), during which the chemical sedimentary succession was uplifted and extensively eroded; this erosion was largely along the southern part of the TB succession, essentially coincident with the paleo-Rand anticline (e.g., Eriksson et al 2001;their Figure 8).…”

Late Neoarchaean-Palaeoproterozoic supracrustal basin-fills of the Kaapvaal craton: Relevance of the supercontinent cycle, the "Great Oxidation Event" and "Snowball Earth"?

“…This geometry, allied to the predominant marly composition of the Duitschland, suggest an origin related to major weathering and erosion of Chuniespoort chemical lithologies during the hiatus (estimated between ca. 80 my and 200 my; respectively, Eriksson et al, 2001;Mapeo et al, 2006) separating the Chuniespoort Group from the succeeding Pretoria Group (Eriksson et al, 2001).…”