A new incompletely broken microcontinent has been identified between Greenland and Canada

Plate tectonics is the driving force behind Earth’s continental configurations, with the lithosphere (oceanic and continental crust and upper mantle) moving due to convection processes occurring in the softer underlying asthenospheric mantle. Many earthquakes, volcanic eruptions and mountain formations are a direct result of the movement of these globe plates, especially at their edges.

One such plate boundary occurs between Canada and Greenland, which created the Davis Strait seaway connecting two ocean basins, the Labrador Sea and Baffin Bay. The tectonic evolution of Davis Strait is dated to ~33–61 million years ago (Ma) during the Paleogene, during which one particularly unusual feature formed—a thicker-than-normal (19–24 km) fragment of continental crust in the ocean.

This is now considered to be a newly recognized, incompletely rifted and submerged microcontinent off the coast of West Greenland: the Davis Strait protomicrocontinent.

Understanding the mechanism and reason for this cortical anomaly is the focus of new research, published in Gondwana research. Doctoral researcher Luke Longley and Dr. Jordan Phethean (University of Derby, United Kingdom) together with Dr. Christian Schiffer (Uppsala University, Sweden) created a reconstruction of ~30 million years of plate tectonic movements that led to the formation of the proto-microcontinent. They define proto-microcontinents as “regions of relatively thick continental lithosphere separated from the main continents by a zone of thinner continental lithosphere”.

Dr. Phethean explains why this particular location is so important to this research, and why it is vital to look at the past formation of microcontinents today. “The well-defined changes in plate motion that occur in the Labrador Sea and Baffin Bay, with relatively limited external complications affecting them, make this region an ideal natural laboratory for studying microcontinent formation.

“Rifting and the formation of microcontinents are absolutely ongoing phenomena – with each earthquake we can work on the next separation of microcontinents. The goal of our work is to understand their formation well enough to be able to predict precisely that future development.”

To investigate this further, the research team used maps derived from gravity and seismic reflection data to identify the orientation and age of faults related to rifting, the mid-ocean ridge (where Greenland separated from the North American plate) and associated transform faults. (where two tectonic plates slide past each other).

The researchers identified an initial rift between Canada and Greenland that began ~118 Ma during the Lower Cretaceous, with seafloor spreading beginning in the Labrador Sea and Baffin Bay at ~61 Ma.

Subsequently, the ~49–58 Ma period is considered key to the formation of this proto-microcontinent, with the orientation of the seafloor between Canada and Greenland changing from northeast–southwest along the Pre-Ungava transform margin to north–south. , break off the Davis Straight proto-microcontinent. At ~33 Ma, oceanic spreading stopped when Greenland collided with Ellesmere Island, after which Greenland joined the North American plate.

In this model, the Davis Strait proto-microcontinent is identified based on crustal thickness, where the microcontinent appears within 19–24 km of thinned continental crust, surrounded by two narrow belts of thin (15–17 km) continental crust. which separate it from mainland Greenland and Baffin Island.

This research is applicable to other microcontinents around the world to understand their calving from continental crust, including the Jan Mayen microcontinent northeast of Iceland, the East Tasman Rise southeast of Tasmania, and the Gulden Draak Knoll off the coast of Western Australia.

Dr. Phethean notes, “A better understanding of how these microcontinents form allows researchers to understand how plate tectonics works on Earth, with useful implications for plate tectonic hazard mitigation and the discovery of new resources.”

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