Sequence stratigraphy and plate tectonic significance of the Transvaal succession of southern Africa and its equivalent in Western Australia

The Transvaal succession in the northeastern part of the Kaapvaal Province of southern Africa is the erosional remnant of four, 2.7 to 2.1 Ga unconformity-bounded stratigraphic units, or sequences, each of which is 10(2) to 10(3) m thick and spans 10(7) to 10(8) years. Three of these Phanerozoic-like cratonic sequences occur in the western part of the Kaapvaal Province and in the Pilbara Province of Western Australia; thus, the two provinces once were part of the same continent, Vaalbara. The stratigraphically lowest sequence historically assigned to the Transvaal succession is part of the Ventersdorp Supergroup in Kaapvaal and the upper part of the Fortesque Group in Pilbara. It consists predominantly of arkosic sandstone and basaltic andesite; it probably is less than or equal to 2687 +/- 2 Ma. The second sequence contains the quartz arenites, dolomites, and banded-iron formations of the Transvaal and Griqualand West successions in the Kaapvaal and the Hamersley Group in the Pilbara. The span of ages (2684 +/- 6 to 2432 +/- 31 Ma), lithologies, and geographic extent of this sequence imply that the Limpopo orogeny, which welded the Zimbabwe Province to Vaalbara, is less than or equal to 2.47 Ga (not 2.67 +/- 0.05 Ga). The third sequence (the Pretoria and Postmasburg groups in the Kaapvaal and the lower part of the Wyloo Group in the Pilbara probably is the elastic wedge generated by the Limpopo orogeny. The fourth sequence (dominated by the felsites of the Rooiberg Group) is restricted to northeastern Kaapvaal. Sequence stratigraphy, lithostratigraphy, and lithofacies indicate that the Pilbara rifted from the southern edge of western Kaapvaal. The Penge Iron Formation in northeastern Kaapvaal, the Asbesheuwels Iron Formation in southwestern Kaapvaal and the Brockman Iron Formation in the Pilbara are the same formation, in which cyclothemic units 0.6 to 15.0 m thick extended greater than or equal to 1200 km.