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- Title
A distinct unconformity in the Cango Caves Group of the Neoproterozoic to early Paleozoic Saldania Belt in South Africa: its regional significance.
- Authors
Praekelt, H. E.; Germs, G. J. B.; Kennedy, J. H.
- Abstract
The discovery of deep karstic features, associated with a sharp contact between the carbonate-containing Kombuis Member of the Matjies River Formation and the oveflying shaley (lower) part of the Groenefontein Formation of the Cango Caves Group (CCG) in the southwestern Cape in South Africa indicates that it represents an unconformity which was formed sub-aerially. Previous chrono-, chemo- and biostratigraphic data are supported by genetic stratigraphy, which suggest that the unconformity, called the Groenefontein Unconformity, can be co related with the Vingerbreek Unconformity occurring in the southern Nama Group, Namibia. This information enables more reliable correlation of the stratigraphic units of the Cango Caves and the Mama Groups and indicates modification of previously proposed correlations, A correlation between the Kombuis Member of the Matjies River Formation (CCG) with the Kuibis Subgroup (Nama Group) as well as the Groenefontein Formation (CCG) with the Vingerbreek Member of the lower Schwarzrand Subgroup (Nama Group) is proposed. The correlation of the Nooitgedagt Member (CCG) with units of the Port Nolloth and Nama Groups is less certain. The Nooitgedagt Member may be a correlate of the Holgat Formation of the Port Nolloth Group or of the lower part of the Kuibis Subgroup of the Nama Group in Namibia. It may also be possible to correlate the Nooitgedagt Member with an even older formation of the Port Nolloth Group. The Groenefontein and Vingerbreek unconformities were probably formed as result of a drop in sea level caused by a circa 547 Ma minor glaciation which occurred during Latest Ediacaran times in southwest Gondwana.
- Subjects
SOUTH Africa; GEOLOGY; PETROLOGY; CANGO Caves Group (South Africa); MATJIES River Formation (South Africa); SEDIMENTARY rocks; METAMORPHISM (Geology)
- Publication
South African Journal of Geology, 2008, Vol 111, Issue 4, p357
- ISSN
1012-0750
- Publication type
Article
- DOI
10.2113/gssajg.111.4.357