Irrigasie Fm
Type Locality and Naming
Springbok Flats Basin. Named after the farm Irrigasie in the Springbok Flats area, north of Pretoria. It was established as a formal lithostratigraphic unit to describe the red bed and sandstone succession that sits between the coal measures and the desert sandstones within this isolated, fault-bounded basin. Lower formation in Stormberg Gr in Springbok Flats Basin
Synonym:
Lithology and Thickness
A predominantly fine-grained, red-bed succession that reaches a maximum thickness of approximately 200 meters. The lower portion consists of dark-grey mudstones and medium- to coarse-grained fluvial sandstones. It grades upwards into the Worthing Member, which is dominated by soft, easily weathered, reddish-brown, purplish, and greenish claystones and siltstones (mudrocks) with subordinate sandstone lenses and minor conglomerates.
Relationships and Distribution
Lower contact
Rests unconformably (and often disconformably) upon the coal-bearing shales and sandstones of the Hammanskraal Fm (the local equivalent of the Ecca Gr/Vryheid Fm).
Upper contact
Conformably and transitionally overlain by the fine-grained, pale-yellow aeolian desert sands of the Clarens Fm.
Regional extent
Geographically restricted to the Springbok Flats Basin, an elongate synclinal flexure located north of Pretoria (stretching between towns like Bela-Bela, Settlers, and Zebediela). Stormberg Gr equivalent (and historically, upper Beaufort Gr equivalent). Its upper section (the Worthing Member) is lithologically identical to, and in modern regional revisions often formally reassigned to, the Elliot Fm. Its lower portions are generally correlated with the Molteno Fm.
GeoJSON
Fossils
Age
Depositional setting
Continental fluvial to shallow lacustrine environments.
Additional Information