Volcanic activity primarily focuses on zones where tectonic plates meet or move away from each other. In addition, volcanoes form far away from plate boundaries due to hotspot volcanism. Here, hot material rises from the Earth’s interior via a so called plume towards the surface and breaks through the Earth’s crust to form a volcano. As the plates move across the hotspot, volcanic island chains such as the Hawaiian chain form.
In Greenland and the North Atlantic region, there are numerous extinct volcanoes from around 60 million years ago. They are not arranged in chains but distributed over a large area of the North American and Eurasian plates, so they do not appear as hotspot volcanism. However, a team of scientists around first author Bernhard Steinberger, GFZ section Geodynamic Modelling, was now able to show that these volcanoes can as well be explained by hotspot activity. Their results are now published in Nature Geoscience.
Using high-resolution tomographic imaging techniques, the team has located a thinned-out corridor within the Earth’s lithosphere stretching from east to west across central Greenland. It may have formed when Greenland moved westwards 90 to 60 million years ago across the Iceland plume that is active here within Earth’s interior. The team now reconstructed the activity of the Iceland plume with high precision.
Steinberger: “After reconstructing the activity of the Iceland plume we were still looking for an explanation why, if the hotspot was already active 90 million years ago in the west of Greenland, volcanic activity only started about 60 million years ago.”
With a new model the scientists were able to reconstruct how hot material rising from the plume accumulated within the corridor. Like this the Earth’s lithosphere thinned out gradually, starting 90 million years ago. Steinberger “Together with the process of plate drift at the North Atlantic Ridge and movements in the Earth’s interior we assume that the originally thick lithosphere thinned out over the course of millions of years. This eventually led to the eruption of volcanoes 60 million years ago and their arrangement at both ends of the landmass” (ak)
Original study: Steinberger, B., Bredow, E., Lebedev, S., Schaeffer, A., Torsvik, T.H., 2018. Widespread volcanism in the Greenland-North Atlantic region explained by the Iceland plume. Nature Geoscience. DOI: 10.1038/s41561-018-0251-0