- © 2008 Geological Society of South Africa
Pans are a common feature in certain portions of the southern African landscape. One aspect of pan formation may relate to the nature of the geology upon which the pan forms. Klippan, located south of Witbank, Mpumalanga Province, was mined through by opencast methods which exposed the Permian Vryheid Formation (Karoo Supergroup) underlying the pan. This consists of clastic sedimentary strata (conglomerate, sandstone, and siltstone) and coal of the number 1 and 2 seams. Detailed investigations of these strata, based on borehole logs, examination of the pit highwall, structural analysis, photographic mosaics and lateral facies analysis, reveal that the geological succession underlying the pan is no different from the strata elsewhere in the adjacent coalfield. The sequence below the number 1 coal seam and above the number 2 coal seam does not exhibit any extraordinary lithologies, weathering features, sedimentary structures or compactional features that would have caused the pan to have formed at this particular location. The conclusion is that the subsurface geology did not play a role in pan formation. However, on a regional basis, underlying geology does play a role in pan formation as clearly observed in the Witbank – Middelburg region as pans are confined primarily to rocks of the Karoo Supergroup and virtually no pans occur in the pre-Karoo lithologies that surround this northern edge of the Karoo basin.