Clarens Fm
Type Locality and Naming
Main Karoo Basin (SE), Main Karoo Basin (Eastern/Northern Forebulge) of South Africa, extending into the northern basins including Springbok Flats, Ellisras, Tshipise, and Tuli (Figure 5 in article). Upper formation in Stormberg Gr
Synonym: Upper Stormberg Group
Lithology and Thickness
Massive aeolian (wind-blown) sandstones. In the Karoo Supergroup of the Tshipise Basin (and the neighboring Tuli Basin) in northern South Africa, it is divided into Tshipise Member and Red Rocks Member.
The Tshipise Member (Upper Unit): This member forms the upper portion of the Clarens Formation, sitting above the Red Rocks Member and directly beneath the capping Letaba basalts. It consists of remarkably clean, fine-grained, well-sorted sandstone. It is typically white, cream, or pale pink, contrasting sharply with the red beds below it.
The Red Rocks Member (Basal Unit): This member forms the lower portion of the Clarens Formation, resting directly on the siltstones of the Bosbokpoort Fm. It is composed of very fine- to fine-grained clayey (clay-rich) sandstone. It has a distinct pink, red, or brownish-red color, often with a mottled appearance or irregular patches of cream-colored sand.
Relationships and Distribution
Lower contact
Overlies the fluvial sandstones and mudstones of the Elliot Fm in the Main Karoo Basin, and the Irrigasie Fm, Lisbon Fm, and Red Beds Fm in the northern basins (Figure 2; Figure 5 in article).
Upper contact
Capped abruptly by the massive flood basalts of the Drakensberg Group (or the equivalent Springbok Flats / Tuli basalts) (Figure 2; Figure 5 in article).
Regional extent
Widespread across the retroarc foreland system and northern Limpopo area basins (Main Karoo, Springbok Flats, Ellisras, Tshipise, and Tuli) (Figure 5).
GeoJSON
Fossils
Age
Depositional setting
Arid desert with active aeolian dune fields. This represents the final climax of the "overfilled" stage of the Karoo foreland basin, where sedimentation entirely outpaced subsidence (Section 2.1; Figure 2 in article). Tshipise Member features large-scale cross-bedding characteristic of an erg (sand sea) environment. The Red Rocks Member - the high clay content and calcareous concretions indicate that it was deposited in a semi-arid environment.
Additional Information
The Clarens Formation marks the absolute end of the sedimentary evolution of the Karoo basins before the tectonic regime shifted to the Gondwana breakup, which triggered the Drakensberg volcanism (Section 2.1 in article).