Pioneering geophysical work undertaken by Aim-listed Botswana Diamonds has identified kimberlite pipes buried at shallow depth on the company’s Thorny River prospect, in South Africa's Limpopo province.
The company says the targets identified are similar to the pipe that constituted the high-grade and famous De Beers Marsfontein mine, in so much as the pipe had little surface indication, owing to dolerite rock cover, but grew and swelled below the dolerite.
Botswana Diamonds says much of the Thorny River area’s geology is comprised of a dolerite dyke swarm.
Conventional geophysical techniques have been unable to detect kimberlites under the dolerite including those that are deeper seated. Subterrane – a partner of Botswana Diamonds using its proprietary technology – enables the company to explore geophysical anomalies beneath the dolerite and those that are buried.
This could lead to the discovery of kimberlites similar to Marsfontein. So far, Subterrane has identified five such target areas within the Thorny River project area.
Botswana Diamonds chairperson John Teeling commented that it had been long held that there should be high-grade kimberlite pipes other than the Marsfontein mine in the Thorny River area.
“The geology made the discovery difficult; however, new geophysical technologies try to see through the dense dolorite cover. The company pioneering the work, Subterrane, believe they have identified five likely targets to be kimberlites.
“We are working to better define where to drill. The targets are shallow and therefore will not be expensive to drill.”