The main sedimentary carbonate units, as indicated in the Home Building Manual Part 1 & 2, on page 21, comprise:

In Gauteng Province, the carbonate formations comprise the Malmani Subgroup  of the Chuniespoort Group (Transvaal Supergroup), which is ~ 2600–2400 Ma. The Subgroup is subdivided into various formations of which some are chert-poor and some are chert-rich.  The dolomitic formations are, in places, overlain by younger rocks, of the Pretoria Group (2350–2100 Ma), Transvaal Supergroup, and/or the Karoo Supergroup (300–200 Ma), and/or mantled by unconsolidated material of Cenozoic age (≤ 65 Ma). 

In Kwazulu-Natal Province, the carbonate rock is hosted in the high-grade metamorphic rocks of the Marble Delta Formation of the Mzimkulu Group, which is ~ 1300–1250 Ma, which occurs as an oval-shaped outcrop, 10 km north-west of Port Shepstone.  Carbonate rock is also found in the Tugela Group, which is 1300 Ma, located near Kranskop and east of Greytown.

In Mpumalanga Province, the carbonate formations comprise the Malmani Subgroup (Chuniespoort Group, Transvaal Supergroup).  Alteration of dolomite to limestone (de-dolomitization) has occurred in many places due to the intrusion of the Bushveld Complex.

In the North West and Limpopo Provinces, the carbonate formations comprise the Malmani Subgroup of the Chuniespoort Group of the Transvaal Supergroup.  Alteration of dolomite to limestone due to the intrusion of the Bushveld Complex is particularly evident north-east of Mokopane (formerly known as Potgietersrus).

In the Northern Cape Province, carbonate rocks mainly comprise the Campbell Rand Subgroup (Ghaap Group, Transvaal Supergroup), which is ~ 2600–2400 Ma.  Carbonates can also be found in various Groups of the Gariep Supergroup, which is ~ 700 Ma, near Eksteenfontein, as well as in the Schwarzrand Formation of the Nama Group, which is ~ 550 Ma, near Vioolsdrif.

In the Western Cape Province, listed according to location, the carbonate rocks form part of the following:

In the Eastern Cape Province, the carbonate rocks form part of:

Although dolomite (carbonate) related instability may take place in any karstic terrain, most instability features have been noted in the Malmani Subgroup and the Campbell Rand Subgroup.  However, the risk of sinkhole and doline formation in the other groups cannot be excluded.

Areas on Dolomite
Is your town on dolomite?

See the list below: