A log of wood believed to be 50 million years old has been hauled up from below ground at Diavik diamond mine in the N.W.T. — a find that researchers say is remarkable but not uncommon.
In a post about the discovery on Facebook last week, the mine described it as a 136-kilogram (300-pound) log from a redwood tree that it found 240 metres below ground. In an email, a Diavik spokesperson said it was discovered on Feb. 20 during regular mining at the A21 pit while miners were scooping kimberlite ore.
Diavik is located in the tundra on Lac de Gras about 300 kilometres northeast of Yellowknife.
“The kimberlite rock from which the wood was recovered has been dated to approximately 50 million years old using accepted age-dating techniques,” they said. “Consequently, the materials encapsulated within the kimberlite rock, including this wood, are understood to be of the same age.”
The spokesperson said pieces of wood are regularly recovered from Diavik’s kimberlite pipes but this one is notable because of its size. They said that when wood is found in kimberlite, work is paused so that it can be safely removed.
“This discovery is significant, as it offers a rare glimpse into the distant past, enriching our understanding of the ancient environment. It also highlights how mining operations can contribute to scientific research and knowledge,” the spokesperson wrote.
They didn’t say exactly what would happen with the discovery, but did say that Diavik “retains” wood that it’s found, has previously sent pieces for study and that it would be “discussing the future handling of such specimens” as the mine approaches closure.
The Prince of Wales Heritage Centre — the museum and archives for the N.W.T. government — already has a piece of 55-million-year-old wood from a metasequoia tree found at Diavik on display, and another from the neighbouring Ekati diamond mine believed to be 52 million years old within its stored collection.
An online record for the log from Ekati says that the metasequoia was a common swamp plant at the time and that when a kimberlite volcano erupted, the remains of the tree collapsed into the top and was encased in the kimberlite rock. “It is real wood, not mineralized or petrified,” the entry reads.
A spokesperson for the territory’s Department of Education, Culture and Employment said Tuesday the museum hadn’t spoken to Diavik about its recent find.
Alberto Reyes on the other hand, an associate professor in the department of earth and atmospheric sciences at the University of Alberta, said he’s reached out to Diavik — and is interested in getting a sample of the tree.
“It’s a really remarkable find,” he said. “I’ve seen those kinds of things before but also, holy smokes that is a huge log.”
Reyes, a co-author on a recent paper about evidence of palm trees in the N.W.T. 48 million years ago, said he was interested to find out what setting the log was recovered from.
He said scientists know that 50 million years ago the region would have been a humid temperate forest ecosystem with metasequoia, hazel, chestnut and oak-like trees.
“It would almost have looked like Nashville, Tennessee in a way, climate-wise.”
But that paints a broad picture of the land at the time, Reyes said, while studying this newly uncovered tree could yield more specific information.
“The ability to look at year-to-year climate variability deep in time during a period of … our history when it’s a lot warmer than present in the Arctic would be really fascinating. We don’t have a great handle on that yet.”
Is ancient wood still actual wood?
Reyes and Christopher West, the curator of paleobotany at the Royal Tyrrell Museum in Drumheller, Alberta, agree the tree is likely about 50 million years old.
West said there are two ways the mine may have figured out how old its kimberlite pipes are: one method is to look at fossil pollen in the area, which reveals what kind of plants were growing at the time and anchors the material in a particular period. The other involves studying a layer of ash that could be present.
West said it’s also “quite common” to find fossil logs with straight ends that look like they could have been cut with a chainsaw.
He said when there’s flooding or an event in which a lot of sediment is deposited, a dead tree can be partially covered. “Eventually the tree breaks away and aspects of it will get sheared and smoothed out,” he said.
West says the tree may have been preserved through permineralization — a type of fossilization which would render the tree hard to the touch — or through coalification — a process that turns plant matter to coal, in which case it could still feel a bit woody.
Reyes, however, suspects the recently uncovered log may still be wood, at least on the inside. He’s examined specimens from similar settings — such as a piece of wood from a kimberlite pipe in the N.W.T. in 2007 — that looked charred only on the outside.
It meant that Reyes and a colleague were able to do chemical tests to try and reconstruct the climate at the time.
“That was my first kind of toe-dipping into the world of … diamond mines and ancient climate in, in N.W.T. And we’ve sort of kind of kept going from there.”
