Cretaceous biozonation based on terrestrial palynomorphs from two wells in the offshore Orange Basin of South Africa
Bernard Price Institute for Palaeontological Research, University of the Witwatersrand
The C-B1 and O-A1 petroleum exploration wells were drilled by SOEKOR Pty Ltd in 1988 and 1992, respectively, in the Orange Basin off the west coast of South Africa. A palynological analysis of the Cretaceous interval intersected by the two wells, for which the ages were adopted from foraminiferal studies, provides new information on the biostratigraphy and also on reconstructions of the Cretaceous palaeoflora and palaeoenvironment. The spores and pollen used in this study were extracted from over 500 samples of conventional cores, side-wall cores and ditch-cuttings. The identified terrestrial palynoflora includes 41 species of angiosperm and gymnosperm pollen, 85 species of fern and bryophyte spores, and two monolete spore taxa. Several of the pollen and spore taxa are possibly new species. Five palynological zones were established for each of the two wells, which are separated by a latitudinal distance of 300 km. Within the Early Cretaceous intervals of the two wells, there is a considerable degree of similarity in the palynological assemblages, which suggests that the terrestrial plant communities were relatively uniform. For the Late Cretaceous interval, however, there are marked differences suggesting that the plant communities had become more diverse and also that the palynomorphs were being supplied from separate geographical areas.
South Atlantic, marine sediments, pollen, spores, Southern Hemisphere, Mesozoic