Canadian Scientist’s Deep-Diamond Research Reveals Ancient Continent
Lucky Canadian scientists have discovered new evidence in diamonds of ancient continental formation and drift.
During the Archean Eon, 4 to 2.5 billion years ago, the Earth's crust had cooled enough to allow the formation of continents and life began to emerge. The North Atlantic Craton (NAC) is an Archaean block of the Earth's crust that formed the nucleus of a continent which included the modern land masses of southern West Greenland, the Nain Province in Labrador, and the Lewisian complex in northwestern Scotland.
Now, a team of Canadian scientists have identified a remnant of this North Atlantic craton, and according to Science UBC, it was a “chance discovery” made while they were sifting through diamond exploration samples from Baffin Island, which “led to a major scientific payoff.”
Deep Mining Earth’s Evolution
According to University of British Columbia geologist, Maya Kopylova, the chance discovery, which is detailed in a new paper in the Journal of Petrology, was made through the analysis of what are known as “Kimberlite rocks.” Occurring deep within the Earth’s crust in vertical structures known as “kimberlite pipes,” they are the most important source of mined diamonds today. And according to Dr Michael Patterson, in his 2013 paper Kimberlite eruptions as triggers for early Cenozoic hyperthermals, kimberlites formed millions of years ago at depths of 150 to 400 kilometers and over time geological and chemical forces drove them to the surface of the Earth’s crust, “embedded with diamonds.”
The paper’s lead author, Dr. Kopylova, said kimberlites “pick up passengers” on their way to the surface in the form of solid chunks of “wall rocks” that carry data about historical geological occurrences deep within the bowels of the Earth. And by pairing up the stratifications of kimberlite rock samples, and “deeper, mantle rocks,” the scientists were able to reconstruct the shapes of ancient continents.
Diamond crystal in kimberlite matrix. (public display, Field Museum of Natural History, Chicago, Illinois, USA) Image: James St. John / CC BY 2.0)
An Ancient Geological Puzzle With Many Moving Parts
Deep core drill samples taken from a De Beers Chidliak Kimberlite Province property, located in southern Baffin Island, were analyzed by Kopylova and colleagues and soon it became apparent that the wall rocks were “ very special,” as they shared a similar mineral signature with other portions of the North Atlantic craton. Kopylova wrote that it was “easy to tie the pieces together” because adjacent ancient cratons in Northern Canada, Northern Quebec, Northern Ontario and in Nunavu, “have completely different mineralogies.”
Cratons are referred to by scientists as “continental nuclei” that serve as anchors, about which other continental blocks gather. The North American plate still has some of these nuclei present at its center but the other continents have fragmented and re-arranged crating a long and tangled geological history of plate movements. Kopylova said:
“Finding these lost pieces is like finding a missing piece of a puzzle: a scientific puzzle of the ancient Earth can’t be complete without all of the pieces.”
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Sampling 200-Kilometer-Deep Diamonds
The North Atlantic craton fragmented about 150 million years ago and it stretches presently from northern Scotland, across southern Greenland and southwest into Labrador. But the newly identified rock sample covers the diamond bearing Chidliak kimberlite province in southern Baffin Island adding roughly “10 percent to the known expanse of the North Atlantic craton.” Previous attempts at continental reconstructions have been based on much shallower rock samples which had formed at depths of one to 10 kilometers but new technologies allowed this team of researchers to obtain mineralogy samples from “200-kilometers deep.”
The drill core samples taken from deep below the Chidliak Kimberlite Province in southern Baffin Island are described as exceptionally valuable, and very expensive to retrieve - much, much more than the average University Geology department budget would extend to. And it was for this reason the samples were initially provided by Peregrine Diamonds, who were acquired in 2018 by the international diamond exploration company and retailer De Beers.
Kopylova said their partner companies demonstrate “a lot of goodwill by providing research samples to UBC, which enables fundamental research and the training of many grad students.” Now, cynical readers will already be thinking to themselves that there is no way a commercial drilling company would “give away” such expensive drill core samples “in good will,” and they’d be right, for in return, UBC research provides the private drilling company with essential geological information about the deep diamondiferous mantle to support their successful, and highly profitable, diamond mining business.
Top image: Ancient continent was detected using samples from Baffin Island, Canada Source: Ruben / Adobe Stock
By Ashley Cowie