Hokonui Formation Volcanic Vent
Grid Ref (WGS84 Lat/Long in decimal degrees)
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