Carbonaceous High-Alumina Shale in the Transvaal Supergroup: Evidence of Early Proterozoic Karstic Wheathering in a Marine Environment

  • Thomas O. Reimer


Extensive beds of carbonaceous shale occur within a thick sequence of Lower Proterozoic dolostone, the lower Transvaal Supergroup of South Africa. The shale contains such high concentrations of A12O3 (21.9%) and K2O (6.5%) that it is compositionally similar to Precambrian paleosols which developed on a variety of rock types. It is proposed that the alumina was concentrated from contemporaneously exposed dolostone through the removal of over 98 % of the original mass by weathering. The shale contains angular fragments and blocks of chert which are attributed to an insoluble component of the dolostone. The abundant Corg also may have been inherited from the dolostone but the abundant potassium is attributed to the introduction of diagenetic pore fluids.

Stratigraphic relationships reveal that the carbonaceous shale was deposited extensively in the photic zone of a shallow epeiric sea. The shale occurs throughout virtually the entire preserved extent of the Transvaal Supergroup (250000 km2), presumably indicating widespread emergence in adjacent areas and the weathering of voluminous dolostone. The dissolved ions may well have reprecipitated within the basin as dolostone which subsequently weathered, resulting in a chemical cycle. Chert breccia within the shale is attributed to locally high relief which induced debris flows.


Carbonaceous Shale Kaapvaal Craton Breccia Zone Detrital Component Transvaal Supergroup 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Beukes NJ (1986) The Transvaal Sequence in Griqualand West. In: Anhaeusser CR, Maske S (eds) Mineral deposits of southern Africa. Geol Soc S Afr 1:819–828Google Scholar
  2. Brimhall GH, Lewis CJ, Ague JJ, Dietrich WE, Hampel J, Teague T, Rix P (1988) Metal enrichment in bauxites by deposition of chemically mature aeolian dust. Nature (London) 333:819–824CrossRefGoogle Scholar
  3. Button A (1973) The stratigraphic history of the Malmani Dolomite in the eastern and northeastern Transvaal. Trans Geol Soc S Afr 77: 229–248Google Scholar
  4. Button A (1979) Early Proterozoic weathering profile on the 2,200 m.y.-old Hekpoort Basalt, Pretoria Group, South Africa. Univ Witwatersrand Econ Geol Res Unit Inf Circ 133: 19ppGoogle Scholar
  5. Button A (1986) The Transvaal sub-basin of the Transvaal Sequence. In: Anhaeusser CR, Maske S (eds) Mineral deposits of southern Africa. Geol Soc S Afr 1:811–817Google Scholar
  6. Button A, Tyler N (1981) The character and exonomic significance of Precambrian weathering and erosion surfaces in Southern Africa. Econ Geol 75th Anniv Vol, New Haven, pp 686–709Google Scholar
  7. Clay AN (1986) The stratigraphy of the Malmani Subgroup in the Carletonville area, Transvaal: Genetic implications for lead-zinc mineralization. In: Anhaeusser CR, Maske S (eds) Mineral deposits of southern Africa. Geol Soc S Afr 1:853–860Google Scholar
  8. Eriksson KA (1972) Cyclic sedimentation in the Malmani Dolomite, Potchefstroom Synclinorium. Trans Geol Soc S Afr 75:85–97Google Scholar
  9. Eriksson KA, Truswell JF (1974a) Tidal flat association from a lower Proterozoic sequence in South Africa. Sedimentology 21:293–309CrossRefGoogle Scholar
  10. Eriksson DA, Truswell JF (1974b) Stratotypes of the Malmani Subgroup northwest of Johannesburg, South Africa. Trans Geol Soc S Afr 77:211–222Google Scholar
  11. Fryer BJ (1977) Rare earth evidence in iron formations for changing Precambrian oxidation states. Geochim Cosmochim Acta 41:361–367CrossRefGoogle Scholar
  12. Hall AL (1938) Analyses of rocks, minerals, ores, coal, soils, and waters from Southern Africa. S Afr Geol Surv Mem 32:876ppGoogle Scholar
  13. Jackson ML, Tyler SA, Willis AL, Bourbeau GA, Pennington RP (1948) Weathering sequence in clay size minerals in soils and sediments. I. Fundamental generalizations. J Phys Coll Chem 52: 1237–1260CrossRefGoogle Scholar
  14. Muhs DR (1983) Airborne dust fall on the California Channel islands, USA. Arid Environ 6:223–238Google Scholar
  15. Nance WB, Taylor SR (1976) Rare earth element patterns and crustal evolution I. Australian post-Archean sedimentary rocks. Geochim Cosmochim Acta 40: 1539– 1551CrossRefGoogle Scholar
  16. Oberthür T (1983) Metallogenetische Überlegungen zur Bildung des Carbon Leader Reef, Carletonville Goldfield, Witwatersrand, Südafrika. Thesis, Cologne Univ, 214 ppGoogle Scholar
  17. Reimer TO (1983) Pseudo-oolites in rocks of the Ulundi Formation, lower part of the Fig Tree Group, South Africa. Precambrian Res 20:375–390CrossRefGoogle Scholar
  18. Reimer TO (1985a) Volcanic rocks and weathering in the early Proterozoic Witwatersrand Supergroup, South Africa. Geol Surv Finland Bull 331:33–49Google Scholar
  19. Reimer TO (1985b) Rare earth elements and the suitability of shales as indicators for the composition of the Archean continental crust. N Jahrb Min Abh 152:211 -223Google Scholar
  20. Reimer TO (1986) Al2O3-rich rocks from the early Precambrian of the Kaapvaal Craton as indicators for paleosols and other products of decompositional reactions, Precambrian Res 32: 155–179CrossRefGoogle Scholar
  21. Reimer TO (1987) Weathering as a source of iron in iron formations: the significance of alumina-enriched paleosols from the Proterozoic of South Africa. In: Appel PW, La Berge G (eds) Precambrian iron formations. Theophrastus, Athens, pp 601–619Google Scholar
  22. Ronov AB, Balashkov YU, Girin YP, Bratishks RK, Kazakov GA (1974) Regularities of rare earth element distribution in the sedimentary shell and in the crust of the earth. Sedimentology 21:171–193CrossRefGoogle Scholar
  23. Schau M, Henderson MB (1983) Archean chemical weathering at three localities on the Canadian Shield. Precambrian Res 20:189–224CrossRefGoogle Scholar
  24. Truswell J, Eriksson KA (1975) Paleoenvironmental interpretation of the early Proterozoic Malmani Dolomite from Zwartkops, South Africa. Precambrian Res 2: 277–303CrossRefGoogle Scholar
  25. Tyler N (1979) Stratigraphy, geochemistry, and correlation of the Ventersdorp Supergroup in the Deerdeport area, Western Transvaal. Trans Geol Soc S Afr 82:133–147Google Scholar
  26. Turekian KK, Wedepohl KJ (1969) Distribution of elements in the earth’s crust. Geol Soc Am Bull 72: 175–192CrossRefGoogle Scholar
  27. Wheatley CJ, Whitfïeld GG, Kenny KJ, Birch A (1986) The Pering carbonate-hosted Zn-Pb deposit, Griqualand West. In: Anhaeusser CR, Maske S (eds) Mineral deposit of southern Africa. Geol Soc S Afr 1:867–874Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1992

Authors and Affiliations

  • Thomas O. Reimer
    • 1
  1. 1.WiesbadenGermany

Personalised recommendations