Geologists Find Lost Fragment of Ancient Continent
Geologists at the University of British Columbia have discovered by chance a new remnant of an ancient part of Earth’s continental crust: the North Atlantic Craton. The team made a chance discovery while sifting through diamond exploration samples from Baffin Island.
Formed millions of years ago at depths of about 150 to 400 kilometres, Kimberlite rock samples are a mainstay of diamond exploration. These are brought to the surface by geological and chemical forces.
For researchers, kimberlites are subterranean rockets that pick up passengers on their way to the surface. The passengers are solid chunks of wall rocks that carry a wealth of details on conditions far beneath the surface of our planet over timeMaya Kopylova, Geologist at University of British Columbia
When the team analyzed samples from southern Baffin Island, it bore a mineral signature that matched other portions of the North Atlantic craton. Scientists believe that this ancient part of Earth’s continental crust stretches from Scotland to Labrador.
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 mineralogiesMaya Kopylova, The lead Author of the Paper Published in the Journal of Petrology
Cratons are billion-year old, stable fragments of continental crust that anchor and gather other continental blocks around them. Some of them are still present at the center of existing continental plates like the North American plate, but other ancient continents have split and re-arranged into smaller fragments.
Finding these ‘lost’ pieces is like finding a missing piece of a puzzle. The scientific puzzle of the ancient Earth can’t be complete without all of the pieces.Maya Kopylova, The lead Author of the Paper Published in the Journal of Petrology
It is believed that the continental plate of the North Atlantic craton rifted into fragments some 150 million years ago. This is the first time geologists have been able to find mantle correlation in such depth. Previously, reconstructions relating to the size and location of Earth’s plates were based on relatively shallow rock samples in the crust; at depths of one to 10 kilometres.
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. We can put together 200-kilometre deep fragments and contrast them based on the details of the deep mineralogyMaya Kopylova, Geologist at University of British Columbia