When a strait hides a piece of continent
A team of researchers has just revealed the existence of a microcontinent located on the Davis Strait. Formed 60 million years ago when the plates shifted, it could tell us more about microcontinents and how plate tectonics works on our planet.
Between Greenland and Canada lie the Baffin and Labrador Seas, separated by the Davis Strait. A place known not only for its wildlife-rich waters, but also for its particularly thick seabed. This unique feature has now been explained by scientists from the University of Derby in the UK and Uppsala University in Sweden.
And what they found was nothing less than a continent. Or rather, a microcontinent whose formation was aborted, leaving an underwater rocky strip 19 to 24 kilometers thick, which has raised a number of questions among scientists. “A prolonged period of rifting and seafloor spreading between Greenland and North America formed the Labrador Sea and Baffin Bay oceanic basins, connected by the Davis Strait.,”, explain the researchers in their study published in the new issue of the journal Gondwana Research. “However, disagreement exists regarding the exact plate motions between Greenland and Canada, as well as the tectonic evolution of the Davis Strait, with previous models unable to explain the origin of anomalously thick continental crust within the seaway.”
But let’s start at the beginning, 118 million years ago. During Cretaceous, Canada and Greenland, then united within the supercontinent Pangea, began to separate. Tectonic movements created large rifts, forming the Atlantic Ocean in particular. Between Canada and Greenland, the seabed stretches out, forming the Labrador Sea and the Baffin Sea, linked by the Davis Strait, with a thick, enigmatic piece of continental crust in the middle.
Using gravity data collected by satellite and seismic information obtained from ships, the team of researchers, with Luke Longley, a PhD student in geology and geophysics at the University of Derby and first author of the study, were able to build tectonic models of the region. These have helped explain how this proto-microcontinent was formed.
When Canada and Greenland separated, a piece of continental crust broke away from Greenland. Between 58 and 49 million years ago, the orientation of the seabed in the region changed from north-southwest to north-south. This change in orientation prevented this piece of continental crust from developing into a continent. Wedged between Canada and Greenland, the Davis Strait proto-microcontinent would continue to follow this trend until Greenland collided with Ellesmere Island 33 million years ago, putting the brakes on Greenland’s move away.
There are several microcontinents around the globe. Madagascar is probably the best-known, while in polar regions there is the Jan Mayen microcontinent and the Kerguelen Plateau. Microcontinents form as a result of plate tectonics, when part of a continent is separated from the landmass. Larger than islands, microcontinents are geologically distinct from the continent they lie close to, and are generally submerged. The study of microcontinents and their formation is important to researchers in understanding plate tectonics.
Mirjana Binggeli, Polar Journal AG
More on the subject
