STRATIGRAPHY AND PALYNOSTRATIGRAPHY, KAROO SUPERGROUP (PERMIAN AND TRIASSIC), MID-ZAMBEZI VALLEY, SOUTHERN ZAMBIA

The Karoo Supergroup outcropst in the mid-Zambezi Valley, southern Zam bia. It is underlain by the Sinakumbe Group of Ordovician to Devonian age. The Lower Karoo Group (Late Carboniferous to Permian age) consist s of the basal Siankondobo Sandstone Formation, which comprises three facies, overlain by the Gwembe Coal Formation with its economically im portant coal deposits, in turn overlain by the Madumabisa Mudstone For mation which consists of lacustrine mudstone, calcilutite, sandstone, and concretionary calcareous beds. The Upper Karoo Group (Triassic to Early Jurassic) is sub-divided into the coarsely arenaceous Escarpment Grit, overlain by the fining upwards Interbedded Sandstone and Mudsto ne, Red Sandstone; and Batoka Basalt Formations. Palynomorph assemblag es suggest that the Siankondobo Sandstone Formation is Late Carbonifer ous (Gzhelian) to Early Permian (Asselian to Early Sakmarian) in age, the Gwembe Coal Formation Early Permian (Artinskian to Kungurian), the Madumabisa Mudstone Late Permian (Tatarian), and the Interbedded Sand stone and Mudstone Early or Middle Triassic (Late Scythian or Anisian) . The marked quantitative variations in the assemblages are due partly to age differences, but they also reflect vegetational differences re sulting from different paleoclimates and different facies. The low the rmal maturity of the formations (Thermal Alteration Index 2) suggests that the rocks are oil prone. However, the general scarcity of amorpho us kerogen, such as the alga Botryococcus sp., and the low proportion of exinous material, indicates a low potential for liquid hydrocarbons . Gas may have been generated, particularly in the coal seams of the G wembe Coal Formation, that are more deeply buried. (C) 1997 Elsevier S cience Limited.