GRAD PROFILE

Geology PhD student a detective in search of lost fossils

PhD student Arndt Peterhänsel Photo by Arndt Peterhänsel

By Trevor Pritchard

Being a graduate of the Department of Geology and Paleontology, Arndt Peterhänsel is hardly your traditional detective.

In his recently defended PhD project, Peterhänsel tried to account for the mysterious disappearance of fossils from the Palliser Platform - a massive limestone formation that developed 355-365 million years ago during the Devonian period.

"[The Palliser Platform] is one of the biggest platforms to have ever existed on this planet, at least 600,000 square kilometres," says Peterhänsel. "The platform itself extended from Winnipeg all the way to Golden, B.C."

Most of the Palliser Platform is currently underground in the Prairie provinces. Peterhänsel spent three summers conducting research in the Rocky Mountains of Alberta and British Columbia, where the platform protrudes out from the surface. At remote outposts accessible only by helicopter, cut off from the outside world, Peterhänsel collected and analysed more than two tons of limestone from the platform.

However, it wasn't what Peterhänsel found in the rock that intrigued him; it was what had gone missing that piqued his curiosity.

"The platform developed right after the Frasnian-Famennian extinction event," explains Peterhänsel. "During that time - and nobody really knows why - 50 per cent of all marine organisms were wiped out. Every second species was gone."

"Then you look at these rocks, and you hardly find any fossils. And you ask yourself, 'How come you can have up to 600 metres of limestone, formed by [the remains of] animals and plants, but you don't have any fossils? Where are they?'"

Peterhänsel concluded that the presence of endoliths - microscopic organisms that convert skeletons of other organisms into viable energy sources - provided an important clue in explaining the baffling disappearance.

"In modern times, if you go to the Great Barrier Reef in Australia, there are microorganisms - endoliths - that are thriving if they get nutrients. My theory was that if nowadays nutrients trigger an explosion of endoliths, would it be possible the same thing happened in the Devonian?"

"And if true, where did the nutrients come from?"

The late Devonian period, says Peterhänsel, saw the world's first mass forestations, including the land mass that now comprises the Canadian Arctic. Nutrients released into the soil by gymnosperms - deep-rooted seed-producing plants and trees - washed southward onto the Palliser Platform by gigantic rivers, resulting in favourable conditions for the growth of endoliths. Peterhänsel theorizes that this resulting endolith population overwhelmed the platform and obliterated the skeletal remains of previously existing organisms.

Peterhänsel's research is of particular interest to the Canadian oil industry. Before the Palliser Platform hardened into rock, a process that occurred over thousands of years, various species of crabs would digest the platform's sediment and create porous burrows throughout the platform. Over time, oil from other organic-rich deposits seeped into the burrows, meaning that if enough of these burrows were connected, there might exist a vast underground reservoir of oil just waiting to be discovered.

Peterhänsel, however, is aware that the search for oil may be an arduous, time-consuming process. "The fillings of these burrows," he says, "are porous and permeable. They would be conduits for oil which could penetrate into the rock. But unfortunately, not all of the burrows are connected, so [the process of finding these reservoirs] is pretty unpredictable."

Although his thesis was successfully defended in January, Peterhänsel admits that his project got off to an inauspicious start.

"My supervisor, Brian Pratt, went to the Rocky Mountains, I think in '95, and he found a reef which was then seen as a post-extinction reef - which was amazing. A year later, however, he found out that the reef was not post-extinction but belonged to another reef that was pre-extinction."

Peterhänsel laughs. "And then I was stuck! But out of that mistake came this thesis project, which has turned out to be a very interesting field of research."