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Hokonui Formation Volcanic Vent

Grid Ref (WGS84 Lat/Long in decimal degrees)

-20.396944, 29.869167
Follow a small track to the west, some 5.5km beyond the Ngezi River on the Bulawayo Road from Zvishavane (there may be a multitude of side tracks off this depending on gold small-worker activity in the area). Maintain an approximate NNW direction for a distance of approximately 3.8km to a small vlei area. A small dry creek to the south leads to the Mtshingwe River and the outcrop some 400m from the track.
Hokonui Formation, Mtshingwe Group

An outcrop interpreted as a volcanic vent is exposed in the bed of the Mtshingwe River. The outline of the “megabreccia” approximates to the river bed and finer-grained sulphidic tuffs occur along the regional strike to the north and south. However, detailed mapping has not been done. The clasts in the breccia of finer-grained, grey tuffaceous rocks (not unlike the surrounding tuffs) and larger fragments of tonalite which are lithologically and isotopically very similar to the Chingezi tonalite which intrudes the Hokonui Formation to the east.


The matrix to these clasts is very pale green to cream coloured and fine-grained and appears to be a comminuted product of the clast lithologies. The age of the Chingezi tonalite is approximately 2.8 Ga 

Further Reading: 
Chauvel, C., Dupré, B., Todt, W., Arndt, N.T. and Hofmann, A.W. (1983) Pd and Nd isotopic correlation in Archaean and Proterozoic greenstone belts. Eos (American Geophysical Union Transactions), 64, 330. Hall, R. (1983) B.Sc. Dissertation Project, University of Zimbabwe. Martin, A. (1978) The geology of the Belingwe-Shabani schist belt, Geological Survey of Rhodesia, Bulletin, 83. Nisbet, E.G., Bickle, M.J. and Martin, A. (1977) The mafic and ultramafic lavas of the Belingwe greenstone belt, Rhodesia, Journal of Petrology, 18, 521-66. Orpen, J.L., Bickle, M.J., Nisbet, E.G. and Martin, A. (1985) Belingwe Peak (1:100,000), Geological Survey of Zimbabwe. Scholey, S.P. (1989) M.Phil., Ph.D. Transfer Report, University of Southampton, U.K.
Author Credit: 
Tony Martin