The oldest recognisable units in Selati are the volcanic-sedimentary rocks of the Murchison Greenstone Belt. The uranium-lead zircon dating determined the age of these volcanic-sedimentary rocks to be about 3000 million years old. No remnants of the Swazian basement on which they were deposited are found in Selati, but to the north of the Murchison Range, these are present although deformed, metamorphosed and partly remolten.
The Lekkersmaak Granite is intrusive into the metamorphic sedimentary and volcanic rocks of the Murchison Greenstone Belt. This means that the volcanic-sedimentary series existed before the granites intruded. The Lekkersmaak Granite intruded between 2700 and 2800 million years ago. The Willie Granite is a special variety of Lekkersmaak Granite.
Thee Mashishimale suite is clearly intrusive into, and is therefore younger than, the Lekkersmaak Granite. The age of the Mashishimale Grranites has been determined by uranium-lead zircon dating to be about 2680 million years old. This is the most recent Archaen event in the region.
To read more about the geology of Selati download The Geology of Selati Game Reserve (2005), compiled by Laura Batchelor based on text, photographs and a presentation by Prof. Jan Kramer and his geology students from the University of Berne, Switzerland.