LITHOSTRATIGRAPHY OF THE GRAAUW DUINEN FORMATION (CENOZOIC WEST COAST GROUP), SOUTH AFRICA

Abstract

The Graauw Duinen Formation forms part of the Cenozoic West Coast Group and was named after the farm Graauw Duinen 152 south of the Olifants River, where it is well exposed in mining faces of a heavy mineral sand mine. However, these exposures are ephemeral and more enduring natural sections at Cliff Point on the farm Geelwal Karoo 262 were chosen as the type area. The formation was previously regarded as a ‘Member’ of the Alexander Bay Formation, but along with other former subdivisions of this unit, has been elevated to ‘Formation’ status because of their broad significance on regional and even global scales. The formation essentially comprises late Neogene coastal calcareous aeolianites, widely distributed along the Namaqualand coast from north of Elands Bay to the Gariep (Orange) River. Fossils, stratigraphic context and correlation with the marine isotope record indicate that the age of the formation ranges from early to late Pliocene.