Geologists find fragment of ancient lost continent in Canada

lost continent
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Geologists have found part of an ancient lost continent by sifting through diamond samples from Canada’s Baffin Island.

By analysing the samples, the geologists identified part of the North Atlantic Craton (NAC), a remnant of the Earth’s ancient continental crust that stretched from Canada to Scotland. 

These new findings suggest that this continent could be 10% larger than previously estimated.

Baffin is the fifth largest island in the world and is located between the Canadian mainland and Greenland. It’s a vast arctic tract that covers more than 500,000 square kilometres.

While analysing igneous rock samples recovered from diamond exploration drilling in the Chidliak Kimberlite Province at the southern stretches of Baffin Island, researchers identified a mineral signature in the rock they had never expected to find.

The geologists say that the samples are similar to other parts of the North Atlantic Craton which was destroyed around 150 million years ago.

The Kimberlite rock samples were formed millions of years ago at depths of 150 to 400 kilometres. 

Maya Kopylova, a geologist at the University of British Columbia, explained that the new findings add another piece to the ancient continent puzzle.

"The mineral composition of other portions of the North Atlantic Craton is so unique there was no mistaking it.

“It was easy to tie the pieces together. Adjacent ancient cratons in Northern Canada - in Northern Quebec, Northern Ontario and in Nunavut - have completely different mineralogies.”

Researchers used a series of analytical techniques, including petrography, mineralogy, and thermobarometry, to study 120 rock fragments, called xenoliths, taken from the Kimberlite province.

The results indicated that the Chidliak mantle shows contrasts with markers from other cratons, but it resembles the West Greenland NAC rocks due to their bulk composition and mineral chemistry.

"We conclude that the Chidliak mantle demonstrates a similarity to only one adjacent block of cratonic mantle," the authors explain.

"With these samples, we're able to reconstruct the shapes of ancient continents based on deeper, mantle rocks.

"We can now understand and map not only the uppermost skinny layer of Earth that makes up one percent of the planet's volume, but our knowledge is literally and symbolically deeper," adds Kopylova.

The full report is published in the Journal of Petrology.

Reference: MG Kopylova et al. The metasomatized mantle beneath the North Atlantic Craton: Insights from peridotite xenoliths of the Chidliak kimberlite province (NE Canada), Journal of Petrology (2019), DOI: 10.1093 / petrology / egz061

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