Dr Holger Sommer

The Mantle Research Group Bloemfontein (MRGB), under the leadership of Dr Holger Sommer, a senior lecturer in the Department of Geology at the University of the Free State (UFS), has discovered an enormous water reservoir 160 km beneath the Free State.

This discovery, according to Dr Sommer, is the first of its kind in South Africa after he had previously made a similar finding in Colorado, USA.

However, this water cannot be used for human consumption. “It is not frozen water; it is not molecular water; it is not fresh water; it is not salty water; it is OH – water which is sitting in the crystal lattice,” he said.

He said the reservoir was comparable in size to Lake Victoria in Tanzania.
The researchers collected eclogites from the Roberts Victor (Rovic) Mine close to the town of Boshof, south-west of the Free State, for their study.

“The Rovic eclogites are rocks which represent former oceanic crust transported into the earth’s interior by complex plate tectonic processes about 2.0 billion years ago,” explained Dr Sommer.

“These rocks were finally carried back to the earth’s surface by volcanic (kimberlite) eruptions around 130 million years ago. Eclogitic rocks are therefore a window into the Earth’s interior.”

The question from the beginning for all MRGB scientists was: Is there water inside these rocks in such depth, and if so, where is it located?

To answer this question, Dr Sommer and his research fellows separated single mineral grains from eclogite samples and prepared about 100 micrometer (0,1 mm) thick rock sections. Afterwards, specific particle accelerator (Synchrotron) measurements were carried out in the city of Karlsruhe in Germany.

“And indeed, the MRGB found water inside the studied rocks from the Roberts Victor Mine,” he said. “The water was located in defect structures in crystal lattices and along boundaries between single mineral grains.”

“The occurrence of water at such depth would give first evidence that all water of the oceans could be stored five to ten times in the earth’s mantle.”
The study was conducted about a year ago.
 

Media Release
Issued by: Mangaliso Radebe
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Tel: 051 401 2828
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4 December 2009