Science & Technology, Canada (Commonwealth Union) – Researchers have made a groundbreaking discovery by utilizing microbial DNA in surface soil to identify buried kimberlite, the geological host of diamonds. This innovative approach leverages “biological fingerprints” to unveil the composition of minerals concealed deep beneath the Earth’s surface, obviating the need for drilling. The application of modern DNA sequencing to analyze microbial communities marks a pioneering use of this technology in the quest for buried minerals.
The findings, featured in a recent publication in Nature Communications Earth and Environment, introduce a novel tool for mineral exploration, potentially saving prospectors valuable time and resources. Bianca Iulianella Phillips, a doctoral candidate at the University of British Columbia’s (UBC) Department of Earth, Ocean, and Atmospheric Sciences (EOAS), who co-authored the study, asserts that this technique expands the relatively limited arsenal available for locating subterranean ore. Existing tools primarily consist of initial ground surveys and the analysis of elements in the overlying rock.
Phillips indicated that this technique emerged from the need for a more sensitive and precise way to penetrate the Earth’s depths and holds promise in situations where other methods prove less effective.
The interaction between ore and soil leads to changes in the composition of soil microbes. To confirm this phenomenon, the researchers conducted experiments in the laboratory, introducing kimberlite to soil microbes and observing alterations in their abundance and diversity.
Phillips elaborates, “We interpreted these modified microbial communities as indicators of the presence of ore materials, essentially ‘biological fingerprints’ in the soil denoting the existence of concealed mineral deposits.”
Using these “indicator” microbes and their DNA sequences, the research team examined surface soil at an exploration site in the Northwest Territories, where the presence of kimberlite had previously been ascertained through drilling. They identified 59 out of 65 indicators in the soil, with 19 present in significant quantities directly above the hidden ore. Additionally, new indicator microbes were identified to supplement their dataset.
Employing this dataset, they assessed the surface soil at another site in the Northwest Territories where they suspected kimberlite might be present, accurately delineating the topographical outline and location of kimberlite buried meters beneath the Earth’s surface. This demonstrated that indicators from one site could predict the presence of kimberlite at another site. In the future, exploration teams could compile a database of indicator species and use it to assess uncharted locations to ascertain the presence of buried kimberlite deposits.
To gauge the effectiveness of their technique, the researchers compared it to another method called geochemical analysis, which involves analyzing soil elements to identify underlying minerals. The microbial approach proved to be more precise in pinpointing the location of concealed ore.
“Microbes are better geochemists than us, and there are thousands of them,” said lead author Dr. Rachel Simister, who conducted the work as a postdoctoral researcher in the UBC department of microbiology and immunology (M&I). “You might run out of elements to sample, but you’ll never run out of microbes.”
Researchers of the study also pointed out that emerging from the collaborative efforts of a team that included Phillips, Dr. Simister, Dr. Sean Crowe, and the late professor Peter Winterburn, this innovative technique has the potential to accelerate the identification of previously undiscovered kimberlite deposits. Kimberlite rocks are renowned not only as potential sources of diamonds but also for their capacity to capture and retain atmospheric carbon.
Moreover, the applicability of this method extends to other metallic deposits. Ongoing research conducted by the team demonstrates promising outcomes in the identification of porphyry copper deposits.
“You could use this technique to find minerals to fuel a green economy,” explained senior author Dr. Crowe, EOAS and M&I professor and Canada Research Chair in Geomicrobiology. “Copper is the most important critical element that we’ll need more of going forward.”
