Russian Federation – Researchers have explained the present-day melting of the Greenland Ice Sheet by linking the anomalous subglacial melting in Greenland to the influence of a strong geothermal anomaly, a hotspot which resulted from the Iceland mantle-plume. The findings have been published in a reputable Nature Geoscience. One of the researchers is Dr Ivan Kulakov, a geophysicist from Novosibirsk State University (NSU).
“Greenland is a huge storage of ice. If it melts, it is likely to contribute to sea level rise of about seven meters, which might have a wide range of impacts on the global environment and infrastructure. The Greenland Ice Sheet shows decline in the ice at an accelerated rate,” says the head of laboratories at NSU and the Institute of Petroleum Geology and Geophysics, Prof Ivan Kulakov.
Where does the meltwater beneath the ice in Greenland come from? Theoretically, the Earth’s internal heat could not heat the continental lithosphere up to the temperatures causing ice melting. An international team of researchers led by Irina Rogozhina and Alexey Petrunin from the GFZ German Research Centre for Geosciences (Potsdam, Germany) found out how to explain this anomaly. They trace the present-day glacier retreat to the distant history of the North Atlantic region, about 80–35 million years ago, when tectonic processes moved Greenland over an area of abnormally hot mantle plume.
The mantle plume is a flow of heat from the Earth’s interior elevated to the Earth’s surface, which is responsible for volcanic activity. Researchers are well aware of the plume beneath Iceland and Greenland. According to some estimates, the plume is ancient and can be dated as 250 million years old. The present-day location of the plume is beneath Iceland, and the volcanic activity on the island is caused by this hotspot, but millions of years ago Greenland, driven by tectonic processes, moved over that hot mantle material.
The plume heated the lithosphere in Greenland creating an anomaly zone which crosses Greenland from west to east. The location and orientation of the zone can be identified due to the magmatic rock resulting from volcano eruptions of those times detected on both sides of Greenland. The impact of the plume on the Greenland’s future was really dramatic.
“Our team of geophysicists from Novosibirsk State University and the Institute of Petroleum Geology and Geophysics, SB RAS, had come up with a seismic model of the Greenland mantle. According to the model, the central part of the island covers a zone with anomalously low seismic wave velocities. We supposed it was the trace of the Iceland plume.”
The results obtained by the geophysicists from NSU culminated in collaboration with GFZ researchers.
“They interpreted our seismic model in terms of the temperature. The puzzle was almost complete,” says Prof Kulakov.
He says researchers had supposed that Iceland plume influenced Greenland in the past, which resulted in the present-day processes, but it was for the first time when the researchers localized the spot.