Imagine you’re a detective, piecing together life-and-death clues. Now imagine those clues are 700 million years old. 

Peir Pufahl and two master’s students are assembling and analyzing such clues. They are part of a joint initiative between Acadia University and Brazil’s MbAC Fertilizer Corporation, which mines phosphate for fertilizer manufacturing. Pufahl, an Associate Professor in Acadia’s Department of Earth & Environmental Science, is working with Acadia student Justin Drummond and Brazilian student Mariana de Souza Carvalho to determine how certain large phosphate deposits formed in central Brazil.

The aim of the research is twofold: to help MbAC locate phosphate deposits, and to increase understanding about a key time in Earth’s evolution. The study area is MbAC’s phosphate deposits around the town of Campos Belos in the state of Goiás.

“This is a truly fantastic partnership,” says Pufahl. “Not only are we looking at the economic aspect of these deposits, but they’re also scientifically rich.” The project is world class, he adds, because these deposits bracket an important interval of Earth history, just before multi-cellular animals began to appear.

The deposits are estimated at 700–740 million years old, formed when the area was part of a vast inland sea.

The phosphorus cycle

“Understanding the nature of the phosphorus cycle is important because all living things require phosphorus,” Pufahl explains. “It’s a nutrient element. So by understanding how phosphorus cycled on the early Earth, just before the advent of early animals, we can get an idea of some of those conditions that might actually have led to the evolution of these first multi-cellular animals.”

Phosphatic minerals on land are dissolved by rainwater and carried by rivers to the ocean, eventually finding their way into the sediment. Organisms such as algae take up the phosphorus, which in turn is incorporated into the cells of animals that eat the algae.

Once the algae and the organisms that feed on them die, they end up on the sea floor. As their organic matter degrades, the phosphates are liberated to the water between the sediment grains. The waters then precipitate phosphatic minerals, and it’s these minerals that hold the clues to how phosphorus was cycling in the ancient ocean.

Pufahl, Drummond, and Carvalho spent three weeks at the MbAC mine site in August 2012, describing and sampling drill core as well as outcrops throughout the region. They worked closely with MbAC to figure out an exploration model that MbAC could apply to other regions of the basin in its search for phosphorites.

Rare opportunities

This kind of collaborative relationship is becoming rare even at the larger institutions because of shrinking funding sources. “These opportunities exist because in the Department of Earth and Environmental Science we are not only well funded through government agencies, but have excellent collaborative relationships with mining and petroleum companies.” Some people might be surprised that a small university such as Acadia undertakes world-class science, he says. “To be able to take a master’s-level student and bring them onto the international stage like this is exceptional.”

Leandro Silva, MbAC’s Geology Coordinator – Resource Geologist, sees the partnership as valuable economically and scientifically. The work will enhance the interpretation of more than 60,000 metres of drill hole and help to improve mining and exploration strategies, he says.

Carvalho describes the project as a lifetime opportunity, adding that Pufahl teaches with enthusiasm and patience. She was glad for the chance to work with foreigners, she says, not just to gain experience in different working methods, but also for the cultural exchange.

For Drummond, the biggest surprise was how chemically weathered the rocks in Brazil are: they almost fall apart in your hands. He found the work similar to fieldwork, but it didn’t feel like work because he was having fun. He is looking at the physical placement of the phosphorite within the rocks for his thesis and from there will try to figure out the environment and how it formed.

Reading the clues

Sedimentologists read the rock record like a book. “If you envision a book that’s on its side, each page is a layer of rock, but 80 per cent of the pages are missing through erosion and lost time,” Pufahl says. “You have to be a detective, because you have to be able to fill in that missing time by what’s on the pages that are preserved.”

Many of Pufahl’s students have gone on to pursue PhDs and careers with petroleum companies and the mineral industry.

“We have an incredibly high placement rate with our undergraduate and graduate students because of the time we invest with them,” he says. “These are truly world-class opportunities, and I just love to be able to provide them to my students. These opportunities are really important for setting them up for their future.”

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