Discussion on 'Zircon Pb-evaporation age determinations of the Oak Tree Formation, Chuniespoort Group, Transvaal Sequence: implications for the Trans-vaal-Griqualand West basin correlations'

摘要

Walraven & Martini (1995), are to be congratulated on their contribution on the age of the Oak Tree Formation. Nonetheless, some aspects of their presentation require a short discussion, particularly because of the recent developments in the South African Committee for Stratigraphy and the ongoing discussion of the new subdivision of the Griqualand West Supergroup (Johnson, 1995). Moreover, this is a welcome opportunity for making new age data available to the geo-scientific community in South Africa. In the light of these new, yet unpublished, precise zircon ages for tuffs from the Campbell Group in Griqualand West (Altermann & Nelson, unpubl. data), discussion on the age of the Oak Tree Formation is even more important. A proper publication of this new data, its discussion, and basin modelling, are to follow elsewhere (Altermann & Nelson, unpubl. data).