Early Triassic palaeoenvironments in the eastern Karoo Foreland Basin, South Africa

Abstract

The Beaufort Group sediments of the Karoo Supergroup in southern Karoo were deposited in a Permo-Triassic foreland basin associated with the development of the Cape Fold Belt. The eastern parts of this basin are often overlooked in palaeoenvironmental reconstructions. During the Early Triassic, deposition occurred in this region on a braided alluvial plain. Vegetation, although restricted to areas adjacent to water bodies, supported a healthy vertebrate population, notably Lystrosaurus and Thrinaxodon. Pulses of sedimentation produced interfingering of sandy Katberg Formation sediments and muddy Palingkloof Member sediments (Balfour Formation), as well as a lateral shifting of facies belts. The cause of these was episodes of tectonic activity associated with the development of the Cape Fold Belt. The source of the sediments was the Proterozoic basement of the Maurice Ewing Bank, which lay to the southeast of the area prior to Gondwana break-up. The exposure of the basement at this time is in marked contrast to the downward flexing of basement in areas further to the west. It defines the eastern side of the Karoo Basin and may account for the very thin sedimentary succession in Dronning Maud Land, Antarctica.