Amazing geological discovery in the Namib
Unknown microorganisms use marble as habitat
In the desert regions of Namibia, Oman and Saudi Arabia, researchers have discovered unusual structures that are likely the result of activity by an unknown microbiological life form.
Research has revealed unusual structures in the Namib Desert that are likely the result of activity by an unknown microbiological life form.Unusual, tiny burrows, or small tubes running vertically through rock in a parallel arrangement, were found in marble and limestone in the desert regions of Namibia, Oman, and Saudi Arabia.
“We were surprised because these tubes are clearly not the result of a geological process,” said Professor Cees Passchier from Johannes Gutenberg University Mainz (JGU), who first noticed the phenomenon during geological fieldwork in Namibia. Later analysis of rock samples revealed traces of biological material, suggesting that microorganisms had tunnelled through the rock.
He told Network Namibia Hub that he has been conducting geological work in Namibia for over 23 years. His research focuses on the geological reconstruction of Precambrian terrains.
An article on the findings by Passchier was recently published in the Geomicrobiology Journal.
Subsequent sample analysis revealed evidence of biological material – apparently, microorganisms had perforated the rock. “We don’t yet know whether this life form is extinct or still alive somewhere,” Passchier explained.
“We examine the structure of the rocks to determine how continents came together to form the supercontinent Gondwana 500 to 600 million years ago,” Passchier added.
At the time, carbonate deposits formed in the ancient oceans and, due to pressure and heat, were transformed into marble. “We noticed strange structures in this marble that were not the result of a geological process.”
Instead of smooth erosion surfaces, tubes could be seen – about half a millimetre wide and up to three centimetres long – aligned parallel to one another and forming layers up to ten metres long. Some calcite crusts had formed along the edges.
The first observations of this kind in the Namib Desert were made 15 years ago. Since then, Passchier has continued investigating the phenomenon in collaboration with colleagues from the Institute of Geosciences at the University of Mainz, as well as Dr Trudy Wassenaar, head of the consulting firm Molecular Microbiology and Genomics Consultants.
Fascinating mystery
The tubes the scientists examined were not hollow but filled with a fine powder of pure calcium carbonate.
It is assumed that microorganisms possibly bored the tunnels to extract nutrients present in the calcium carbonate, which is the main component of marble. The fine powder was left behind.
Passchier also found many similar structures during fieldwork in Oman and Saudi Arabia – in limestone in Oman and marble in the Saudi Arabian desert.
“These are, in any case, ancient structures – possibly one or two million years old,” said Passchier. “We assume they were formed in a slightly more humid climate, not in the desert conditions that prevail today.”
The organism responsible for these structures, however, remains a mystery.
Microorganisms such as bacteria, fungi or lichens are found even in the most inhospitable and remote corners of the Earth. So-called endolithic microorganisms are not unusual in desert regions, as they can derive their energy and nutrients from the rocks they inhabit.
“What’s so exciting about our discovery is that we don’t know which endolithic microorganism it is. Is it a known form of life or an entirely unknown organism?”
According to Passchier, it must be an organism capable of surviving without light, since the tubes were formed deep within the rock. The researchers found biological material but no DNA or proteins that could provide further insights.
Scientific enquiries
Passchier hopes that specialists in endolithic organisms will study this phenomenon in the future. “This form of life, which we don’t know whether it still exists, could be significant for the global carbon cycle. It is therefore essential that the scientific community becomes aware of it.”
The release of carbon through the biological activity of microorganisms may also play a major role in the Earth’s carbon dioxide balance.
*Cees Passchier was a professor in tectonophysics and structural geology at the Institute of Geosciences at Johannes Gutenberg University in Mainz from 1993 to 2019. Since 2019, he has been a senior research professor in geoarchaeology at JGU. The current research article, ‘Subfossil Fracture-Related Euendolithic Micro-burrows in Marble and Limestone’, has been published in Geomicrobiology Journal. – [email protected]