Fossil woods of Karoo age deposits in South Africa and Namibia as an aid to biostratigraphical correlation

Abstract

The Karoo Basin extended from South Africa, through Namibia, into adjacent southeastern South America during the Pal˦ozoic. Sedimentation in different parts of the basin varied in depth and duration, so attempts have been made to correlate the smaller basins within the whole region. Vertebrate fossils are rare in Namibia, as are good macroplants, but fossil wood is abundant. Samples have been collected from the Tsarabis, Huab and Gai As Formations and the Krone Member of the Etjo Sandstone Formation from several localities. The woods have been identified and correlated with woods from known biozones from the main South African Karoo Basin. Based on the wood the Tsarabis Formation is equivalent to the Ecca and Beafort Groups (Permian: Prototaxoxylon africanum, Araucarioxylon africanum and Araucarioxylon karooensis). The Huab Formation is equivalent to the Upper Beaufort Group (Permo-Triassic: Protopodocarpoxylon sp., A. africanum). The Gai As Formation has woods of the Upper Beaufort and even the Jurassic (Permo-Triassic-Jurassic?: Protopodocarpoxylon cf. P. lamtharii, Protopinace˦, A. africanum). An alternative interpretation is that the Protopinace˦ evolved earlier than the Jurassic in Namibia. The wood from the Krone Member ( A. karooensis) occurs in the South African Upper Beaufort so the range of this wood should be extended. More woods need to be examined to confirm this preliminary biostratigraphy and it needs to be further tested with other fossil data. The boundaries between the formations cannot be determined by the woods.