Terrestrial Vertebrate Colonisation and the Ecca-Beaufort Boundary in the Southeastern Main Karoo Basin, South Africa: Implications for Permian Basin Evolution

Stepping out across the Karoo retro-foreland basin: Improved constraints on the Ecca-Beaufort shoreline along the northern margin

“…Furthermore, some of the lithofacies that dominate this interval, and the interpreted depositional environments, are very similar to those described from the Waterford Formation of the Ecca Group by Rubidge et al (2000) and Mason et al (2015) from the south-western and south-eastern main Karoo Basin, respectively. In particular, Rubidge's (1988) Facies A and E, which are considered to be most diagnostic of the Waterford Formation further south in the basin (Rubidge et al, 2000(Rubidge et al, , 2012Mason, 2007;Mason et al, 2015), correspond directly with Lithofacies types R and Sd, respectively.…”

“…Furthermore, some of the lithofacies that dominate this interval, and the interpreted depositional environments, are very similar to those described from the Waterford Formation of the Ecca Group by Rubidge et al (2000) and Mason et al (2015) from the south-western and south-eastern main Karoo Basin, respectively. In particular, Rubidge's (1988) Facies A and E, which are considered to be most diagnostic of the Waterford Formation further south in the basin (Rubidge et al, 2000(Rubidge et al, , 2012Mason, 2007;Mason et al, 2015), correspond directly with Lithofacies types R and Sd, respectively. Based on lithologic and genetic similarities, we consider the stratigraphic interval where FA2, FA3, and FA4 occur to be lithologically equivalent to the Waterford Formation, which forms the uppermost stratigraphic unit of the Ecca Group in the south of the main Karoo Basin, and these rocks should thus be included within the Ecca rather than the Beaufort Group.…”

“…In the southern Karoo Basin, the currently accepted lithostratigraphic contact between the Ecca and Beaufort groups is taken at the Waterford-(uppermost Ecca Group) Abrahamskraal (lowermost Beaufort Group) contact (Cole et al 2016;Rubidge et al 2012). This reflects a change in depositional environment from subaqueous conditions to subaerial fluvial environments (Johnson, 1976;Rubidge et al, 2000Rubidge et al, , 2012Welman et al, 2001;Mason et al, 2015). However, the Waterford Formation is not mapped north of 30° 40' S (1:1M Geological Map 2019, Council for Geoscience, Pretoria), with the contact of the Ecca and Beaufort groups instead being shown at the contact between the shales of the Tierberg or…”

“…Because of this, current understanding of vertebrate distribution in the main Karoo Basin and mid-to late Permian Beaufort Group biostratigraphy is based mostly on results from the southern parts of the basin (e.g. Kitching, 1977;Keyser and Smith, 1979;Rubidge, 1995Rubidge, , 2005Mason, 2007;Rubidge et al, 2013;Mason et al, 2015;Smith et al, 2020). This paper reports on the sedimentary characteristics documented across the Ecca-Beaufort contact in the distal sector of the main Karoo Basin (sensu Catuneanu et al, 1998) and assesses whether the same criteria used to define the Ecca-Beaufort contact in the proximal sector of the main Karoo Basin can be applied to these outcrops.…”

Unique trackway on Permian Karoo shoreline provides evidence of temnospondyl locomotory behaviour

“…In the southern Karoo Basin, the Waterford Formation constitutes the uppermost Ecca Group [38][39][40][41][42][43], but has recently been shown to also be present in the north of the basin, where it gradationally overlies the Volksrust or Tierberg formations [37]. This diagnostic and easily recognisable formation, which incorporates strata previously assigned to the upper Volksrust and/or conformably overlying lower Balfour Formation (including the now defunct Normandien and Estcourt formations [36,37]), is characterized as being generally arenaceous in nature, generally ripple-marked, as well as containing rhythmically-bedded carbonaceous shale and ubiquitous soft sediment deformation structures (Fig 3).…”