Overberg Geoscientists Group
2050 Mya
Phalaborwa Igneous Complex
The 2050 ± 2 Ma Phalaborwa Complex is a composite, pipe-like, ultramafic to carbonatite intrusion formed from multiple magma pulses. It is located in Limpopo Province, South Africa (e.g. Hanekom et al., 1965) on the edge of the town of Phalaborwa, adjacent to the Kruger National Park (KNP) in north-east South Africa.
It is the oldest carbonatite in southern Africa and is the only known carbonatite with economic copper deposits. It has been extensively mined over many years, primarily for copper, vermiculite and other minerals including magnetite, nickel, gold, silver, uranium, rare earth elements and platinum group elements.
It is the oldest carbonatite in southern Africa and is the only known carbonatite with economic copper deposits. It has been extensively mined over many years, primarily for copper, vermiculite and other minerals including magnetite, nickel, gold, silver, uranium, rare earth elements and platinum group elements
Formal mining of the Complex started in 1956 with the creation of the Palaborwa Mining Company. Historically, mining and smelting of copper and iron ore date back to 400 A.D. when the Sotho called the area 'Ba-Phalaborwa', meaning 'better than the south'.
The Phalaborwa Igneous Complex was formed from several compositionally distinct magmas and is surrounded by many prominent small conical hills (kopjes) and spires, including some within the adjacent parts of KNP. Recently published geochemical and oxygen isotope studies on the Phalaborwa Complex have provided new insights into its genesis and mantle source characteristics.
Prior to the mining activity, this complex fell within the boundary of KNP. Fortunately, it was located close enough to the western boundary of the Kruger National Park, so that the land it on which it occurs could be exchanged for land which is now included in KNP.
The Phalaborwa Complex is situated roughly halfway between the Drakensberg Escarpment in the west and the Lebombo Mountains to the east on the Lowveld, at an average height of 350 metres above sea level. Around Phalaborwa the rather flat and monotonous topography is broken by the presence of a large number of scattered, small conical hills. These rise approximately 100 metres above the surrounding Lowveld topography and form a typical inselberg landscape.
The many small inselbergs associated with the Complex consist of syenite, a hard rock-type containing mainly felspar with accessory amounts of quartz. They are intrusive into a basement consisting of granite and granite gneiss of Swazian age (3 000 Ma). The latter rocks are very coarse-grained and weather readily, whereas the syenite is more massive and resistant to erosion. The formation of the present inselberg landscape is thus largely the result of selective differential weathering between the surrounding granite and granite-gneiss basement and the syenites. Some ten syenite intrusions which are part of the larger Complex are located within the KNP, south and south-east of the Phalaborwa entrance gate to KNP.
It is of interest to note that all the major copper deposits in the Transvaal, such as Phalaborwa and Messina, were known to the pre-historic inhabitants of Southern Africa and that these people carried out fairly extensive exploitation of the oxidised surface ores. Verwoerd (1956) described the presence of small smelting furnaces, freestone walls, built-up terraces and copper and iron ingots, which date from this early pre-historic mining period of South African in the Phalaborwa area.
Masorini Syenite Koppie (part of the Phalaborwa Complex Intrusive suite)
Archaeological Site - Iron ore smelting locality.
Further Reading:
Eriksson, S. C. (1989). Phalaborwa : A saga of magmatism, metasomatism and miscibility. In: Bell, K. (Editor). Carbonatites : Genesis and Evolution. London: Unwin Hyman, 221 – 254.
Evers, T.M. and Van Der Merwe, N. J. (1987). Iron Age Ceramics from Phalaborwa North Eastern Transvaal Lowveld, South Africa. S. A. Archaeological Bulletin, 42, No. 146, 87 - 106 .
Frick, C. (1975). The Phalaborwa syenite intrusion. Trans. Geol. Soc. S. Afr., 78, 201–214.
Harger, H. S. (1934). An early Transvaal geological map by Carl Mauch. Trans. Geol. Soc. S Afr., 37, 1 – 4.
Munro, J and Harris, C. (2023). A High-δ18O Mantle Source for the 2.06 Ga Phalaborwa Igneous Complex, South Africa? Journal of Petrology, 64(9), 1 – 19.
Palabora Mining Company Limited. (1976). The geology and economic deposits of copper, iron, and vermiculite in the Palabora Igneous Complex : a brief review. Economic Geology, 71, 177–192. https://doi.org/10.2113/ gsecongeo.71.1.177.
Southwood, M. and Cairncross, B. (2017). The minerals of Palabora, Limpopo Province, South Africa. Rocks and Minerals, 92, 426–453. https://doi.org/10.1080/00357529.2017.1331398.
Verwoerd, W. J. (1956). Sekere produkte van primitiewe koper-yster-en bronssmelterye in Oos Transvaal met besondere verwysing na Phalaborwa. Tegnikon, 9, 91 - 104.
Verwoerd, W. J. and Du Toit, M. C. (2006). The Phalaborwa and Schiel complexes. In: Johnson, M.R., Anhaeusser, C.R. and Thomas, R.J. (Editors). The Geology of South Africa, Council for Geosciences, Pretoria., 291 – 318.
Wu, F.Y., Yang, Y.H., Li, Q.L., Mitchell, R.H., Dawson, J.B., Brandl, G. and Yuhara, M. (2011). In-situ determination of U–Pb ages and Sr-Nd–Hf isotopic constraints on the petrogenesis of the Phalaborwa carbonatite complex, South Africa. Lithos, 127, 309 – 322.
https:// doi.org/10.1016/j.lithos.2011.09.005.