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Canadian geologists investigating deep samples from the coast of Baffin island, discovered a previously unknown fragment of the North Atlantic craton — a part of the ancient continental crust of the Earth.
About the opening described on the website of the University of British Columbia. Samples of kimberlite for the study of geologists has provided one of the companies which is engaged in the exploration for diamonds. They were taken from the island of Baffin island, located in the canadian province of Nunavut.
These rocks were formed millions of years ago at depths from 150 to 400 kilometers. Kimberlites rise to the surface due to geological and chemical processes and sometimes bear diamonds.
“For researchers kimberlites is an underground rocket that carries the passengers to the surface, explains geologist of the University of British Columbia Maya Kopylova. — The passengers are pieces of rocks that bear a lot of detailed information about the conditions deep under the surface of our planet.”
Analysis of the samples showed that they in its composition identical to the samples from the North Atlantic craton. The cratons is stable fragments of continental crust, whose age is one billion years. Some of these continental nuclei are still present in the centers of the existing continental plates such as the North American plate.
Other ancient continents split into smaller fragments and was reconstructed during the long history of plate motion. One of them found by scientists in Northern Canada. It is believed that the continental plate of the North Atlantic craton exploded into fragments of about 150 million years ago.
It currently stretches from the North of Scotland through the southern part of Greenland, and stretches South-West to the Labrador. The fragment covers diamondiferous province in the South of Baffin island. This discovery increases the area of the North Atlantic craton approximately 10 percent.
“Mineral composition of other parts of the North Atlantic craton is so unique that could not be mistaken, — tells Maya Kopylova. — It was easy to tie everything together. Neighboring the ancient cratons in Northern Canada, in Northern Quebec, Northern Ontario and Nunavut — have a completely different mineralogical compositions”.
In her opinion, to find these “lost pieces” — it’s like finding the missing piece of the puzzle. This is the first time when geologists were able to collect the pieces of the puzzle together in such a great depth. The previous reconstruction of the size and location of the Earth’s plates were based on the study of samples formed at depths of from one to 10 kilometers.
“Using these samples we can reconstruct the forms of ancient continents on the basis of deeper mantle rocks, says Kopylov. Now we can map not only the top thin layer of Earth, which is one percent of the volume of the planet. Our knowledge is literally gone deeper. We are able to reassemble the fragments generated at a depth of 200 kilometers.”
All the study presented in the journal journal of Petrology.
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