Changing our understanding of the world one rock (succession) at a time
Professor Nicolas Johannes Beukes is director of the department of science and technology (DST)- National Research Foundation (NRF) Centre of Excellence for Mineral and Energy Resource Analysis (Cimera), hosted in the department of geology at the University of Johannesburg (UJ).
This A1 NRF-rated scientist is considered a world leader in the study of iron and manganese ore deposits, two commodities that are vital to South Africa’s economy. His work has led to improved exploration, mining and processing of these ores.
Becoming a world leader or, as the professor humbly puts it “a specialist”, doesn’t happen overnight. Most of us don’t start tertiary education knowing exactly what we are going to do. Beukes, however, went to the University of the Orange Free State knowing he wanted to become a geologist.
His roots are in Harrismith in the Free State. “I liked going out in nature, so I became interested in geology,” says Beukes. The interest in geology was further entrenched by his high school physical science teacher, Mike Marais.
Iron formations and the ‘Snowball Earth’
Beukes began his research on iron formations, a type of sedimentary rock that forms from a chemical precipitation in ocean water. Sedimentary rocks are surface and near-surface rocks, such as sandstone, shale and limestone.
“Iron formations were abundant up to two billion years ago, after which they virtually disappeared,” says Beukes. “Then a few were deposited 750 million years ago, and now there are no modern examples. They have gone again.” The question is why?
His research showed that there was more iron dissolved in the oceans when iron formations were deposited. No iron formations could be deposited when there was a depletion of iron in oceans.
“About 750 million years ago, iron formations returned, showing there was an increase in iron in the oceans then. It was a very interesting time. The earth was in a ‘Snowball’ state when it was almost completely frozen over, up to the equator,” explains Beukes.
“Thermal activity, such as volcanism, continued to seed the oceans with iron. When the ‘Snowball Earth’ thawed, the iron reacted with atmospheric oxygen and precipitated iron formation again.”
Beukes was one of the first scientists to develop models, based on field work, showing how iron formations actually formed. “It’s important to understand: what were the processes? What were the conditions of the oceans and the atmosphere?” says the professor. Some of his models are still used today.
Research on iron, manganese and gold
Later in the 1990s, Beukes started work on the world’s iron deposits.
“South Africa has some of the best and highest grade iron ore deposits, [with] up to 65% iron,” says Beukes. There are, however, deposits in Brazil and Western Australia that are larger.
Beukes says that these iron ore deposits are all hosted in iron formations. These are precursor rocks for high-grade iron deposits (iron formations consist mainly of iron and silica minerals).
The professor studied the processes for the dissolution of silica to create iron ore deposits. To do that he studied global iron ore deposits and then developed a classification scheme for the different types; this is important for exploration to find new deposits and for mining of the deposits.
Beukes also studied the Kalahari Manganese Field (KMF) near Kuruman. It contains 78% of the world’s known land-based manganese resources. He worked on these in 1980s and 1990s and continues to research this area.
“Very little was known about how manganese ores formed, nor their detailed composition, which is important for smelting,” says Beukes. These are now known from the research work done in the KMF and other parts of the world.
His research includes an important contribution to gold exploration. In the early 1990s, he and a collaborator published a paper correlating the gold-bearing Witwatersrand rocks with similar rocks of the Pongola sequence in KwaZulu-Natal. It showed the rock sequences were the same age and formed in a single sedimentary basin. This suggests that there is a probability of Witwatersrand-type gold deposits occurring in KwaZulu-Natal.
Rethinking when oxygen existed on earth
Beyond iron and manganese, Beukes is also recognised as a world leader in the study of the oxygenation of the Earth’s atmosphere.
“Soil, prior to 2.4-billion years ago, is mainly white, indicating there was very little oxygen at the time,” explains Beukes. “After 2.4 billion years, you start seeing the first red soils, showing that there was oxygen in the atmosphere.” Put simply, the earth began to rust.
Beukes and co-researchers discovered red (rusted) soils in rocks that were much older than 2.4 billion years, showing there was some oxygen in the atmosphere then.
Dating carbonate platforms
Beukes was also the first to show that the thick Campbellrand-Malmani carbonate platform succession of the Transvaal Supergroup in South Africa is the oldest example and the best preserved in the world. The Bahamas is a modern-day example of a carbonate platform.
The Transvaal carbonate platform formed around 2.6-billion years ago. Beukes “decoded” the configuration of the platform and its development through time. The rocks consist of stromatolite sedimentary structures, created by oxygen-producing organisms such as cyanobacteria.
Beukes says he is currently part of a team that is investigating the carbonate platform further. In 2016, they drilled into it near Kuruman for fresh rock samples. The hypothesis being tested is: if there were cyanobacteria around, there should also have been eukaryotes (a more complex form of life – a cell with a nucleus that uses oxygen). To date, no one has found 2.6 billion-year-old eukaryote fossils. The samples are overseas for analysis as South Africa doesn’t have the necessary specialised research equipment.
Investigating shale gas
Later in his career, Beukes began to study the age and source material of the Cape and Karoo sequence rocks. They are 350 to 190 million years old. The Karoo rocks host important coal deposits, as well as potential shale gas and sandstone-hosted uranium deposits.
He is involved in the Karoo Research Initiative, one aspect of which is looking at shale gas potential. Preliminary test results from two research boreholes indicate that very little shale gas is present. This is a novel finding.
His work with DST-NRF Cimera
DST-NRF Cimera focuses on world-class research around economic geology themes. One of the key performance areas is the training of excellent researchers, mainly from South Africa but also from elsewhere in Africa and other countries.
In 2013, Beukes got the go-ahead from the NRF to establish a Centre of Excellence at UJ, in collaboration with the University of the Witwatersrand, to focus on economic geology research. DST-NRF Cimera brings together like-minded economic geologists, has partnerships with nine universities, and involves about 40 scientists and 80 master’s and doctoral students.
All of Beukes’s research has been published, mostly in peer-reviewed journals, presented at scientific conferences, or written up in company reports. He served on the committees of several scientific societies, editorial boards of scientific journals, and is currently associate editor: earth sciences for the South African Journal of Science. This award-winning scientist is an honourary fellow of the Geological Society of America. He has also won the prestigious Draper Memorial Award of the Geological Society of South Africa.
Beukes has supervised and co-supervised over 70 master’s and doctoral students and postdoctoral fellows. “This is one of my biggest contributions. I enjoy working with students. It gives me a lot of satisfaction,” concludes Beukes.