Overberg Geoscientists Group
2600 Mya
Limpopo Mobile Belt
The structures and rock units of the Limpopo Mobile Belt (LMB) have been the subject of extensive research for at least 50 years. The complexity of these rocks with respect to mineralogical and chemical make up as well as structural associations has been an ongoing puzzle.
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Very recent further investigation has disclosed that the previously interpreted similarities to a Himalayan type orogenic belt may be incorrect. Further research in other, more recent orogenic belts has disclosed the presence of features more similar to a “Turkic-type” continental growth model (Barton, et. al. 2006).
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A common feature of LMB geology has always been the great variety of structural styles, whole rock and mineral chemistry as represented in adjacent structurally separated terranes. Comparison of these features with those now identified from Himalayan, Andean and Turkic orogenic environments has concluded greater similarities with the latter.
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Current hypotheses have concluded that the tectonic evolution of the LMB took place over a period of at least 700 million years, between 2,7 and 2,04 Ma.
Figure 1: Geological map of the Limpopo Belt. 1, Mahalapye granite; 2, Mokgware granite; 3, Bulai granite; 4, Matok granite; 5, Razi granite. (Zeh, et.al. 2007).
The structures and rock units of the Limpopo Mobile Belt (LMB) have been the subject of extensive research for at least 50 years. The complexity of these rocks with respect to mineralogical and chemical make up as well as structural associations has been an ongoing puzzle.
Very recent further investigation has disclosed that the previously interpreted similarities to a Himalayan type orogenic belt may be incorrect. Further research in other, more recent orogenic belts has disclosed the presence of features more similar to a “Turkic-type” continental growth model (Barton, et. al. 2006).
A common feature of LMB geology has always been the great variety of structural styles, whole rock and mineral chemistry as represented in adjacent structurally separated terranes. Comparison of these features with those now identified from Himalayan, Andean and Turkic orogenic environments has concluded greater similarities with the latter.
Current hypotheses have concluded that the tectonic evolution of the LMB took place over a period of at least 700 million years, between 2,7 and 2,04 Ma.
Further Reading
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Barton, J. M., Klemd. R., Zeh, A. 2006. The Limpopo Belt: An example of Archean to Proterozoic, Turkic-type orogenesis. Geological Society of America, Special Paper 405. P 316-322.
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Zeh, A., Gerdes, A., Barton, J. M. 2007. Archaean to Proterozoic Crustal Evolution in the Central Zone of the Limpopo Belt (South Africa-Botswana): Constraints from Combined U-Pb and Lu-Hf Isotope Analyses of Zircon. Journal of Petrology, 48(8). P 1605-1639.
John Blaine
July 2023