Monoclines and palaeochannels: evidence for syntectonic sedimentation in the Beaufort Group of the Karoo basin, South Africa
In the south-western part of the Karoo basin, southward-dipping monoclines apparently had an influence on sedimentation patterns in fluvial deposits of the Late Permian-Early Triassic Beaufort Group. Palaeocurrents in this area are generally directed towards the northeast but deviate sharply towards the east on the steep flanks and towards the north on the gently dipping flanks of all five monoclines examined. Lithofacies also show statistically significant differences on the two flanks of the DR-3 monocline which is associated with a major uranium deposit. Structural evidence suggests that the monoclines probably formed after compaction of the sediments, therefore, an earlier phase in their development must have been responsible for the characteristic sedimentation patterns. It is suggested that shallow synclines, related to compressional paroxysms of the Cape orogeny, deflected streams parallel to their axial trends. As uranium occurs preferentially in thick channel sandstones, their association with monoclines can therefore be used as an exploration tool in the Karoo. © 1994.