In recent days, many media outlets have been citing a study published recently in the journal Gondwana Research to argue that North America and Europe should be considered a single continent, and therefore Earth would have one less than previously established.

However, the study actually says nothing of the sort. On the contrary, it argues for the existence of a microcontinent in the Davis Strait, between Canada and Greenland. The finding offers new details about the tectonic restructuring in this region during the Mesozoic and Cenozoic eras.

The Davis Strait is a key region connecting the oceanic basins of the Labrador Sea and Baffin Bay. These basins formed during the divergence between Greenland and North America, a process that began in the Mesozoic and continued into the Cenozoic. However, the tectonic evolution of the Davis Strait has been a topic of debate for decades. Although it is known that the region has an anomalously thick continental crust, existing theories did not fully explain its origin.

Schematic diagram of key events in the Labrador Sea, Baffin Bay and Davis Strait
Schematic diagram of key events in the Labrador Sea, Baffin Bay and Davis Strait. Credit: Luke Longley et al.

The article published in the journal Gondwana Research presents a detailed tectonic reconstruction that sheds light on the separation of Greenland from Canada, proposing the existence of a proto-microcontinent in the Davis Strait, which they have named the “Davis Strait proto-microcontinent.”

To reach these conclusions, the researchers used tectonic reconstruction models based on a comprehensive set of gravimetric data, obtained from vertical gradient maps and filtered directional data. This data allowed them to identify new lineations associated with oceanic ridges and transform fault zones. Additionally, seismic reflection data from the western Greenland region were reinterpreted, complemented by a recently compiled crustal thickness model.

This multidisciplinary approach allowed the identification of an isolated block of continental crust, with a thickness of between 19 and 24 kilometers, that was separated from Greenland during a previously unrecognized east-west extension phase. This block has been interpreted as an incompletely detached microcontinent, referred to as the Davis Strait proto-microcontinent.

Bathymetry map of the Northwest Atlantic. Previous interpretations of the boundaries between the continental ocean are also shown.
Bathymetry map of the Northwest Atlantic. Previous interpretations of the boundaries between the continental ocean are also shown. Credit: Luke Longley et al.

One of the most interesting findings of the study is that the separation of this proto-microcontinent coincides with a change in the orientation of tectonic spreading, which occurred between 58 and 49 million years ago.

This change was driven by the reorientation of the rift margins of Canada and Greenland, indicating that the structure of the lithosphere had a fundamental control over plate movements.

This research not only provides a detailed explanation of the tectonics in the region but also proposes a model that could be applied to other regions of the world where microcontinents have been identified or could be identified. With a better understanding of these processes, scientists are one step closer to deciphering the tectonic dynamics that have shaped the continents as we know them today.

SOURCES

Luke Longley, Jordan Phethean, et al., The Davis Strait proto-microcontinent: The role of plate tectonic reorganization in continental cleaving. Gondwana Research, Volume 133, September 2024, Pages 14-29. doi.org/10.1016/j.gr.2024.05.001

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