Massive meteorite crater discovered under Greenland ice-sheet

A huge meteorite crater that is 31 kilometres wide has been discovered under the ice-sheet in northern Greenland, scientists said on Wednesday.

The crater is estimated to be among the 25 largest impact craters on Earth, according to the study published in the journal Science Advances.

A 1-kilometre-wide iron meteorite is believed to have formed the crater, which is located almost 1 kilometre beneath the ice-sheet.

The crater was initially discovered in July 2015 when researchers inspected a new map of the topography beneath Greenland's ice-sheet under the Hiawatha Glacier.

"The crater is exceptionally well-preserved, and that is surprising, because glacier ice is an incredibly efficient erosive agent that would have quickly removed traces of the impact," Professor Kurt H Kjaer of the Centre for GeoGenetics at the Natural History Museum of Denmark said.

The crater was not dated but was likely "younger than 3 million years old and possibly as recently as 12,000 years ago - toward the end of the last ice age," he added.

In the summers of 2016 and 2017, researchers returned to the site and mapped tectonic structures in the rock near the bottom of the glacier and collected sediment samples.

These samples helped researchers determine the crater was caused by a meteorite strike, said Nicolaj K Larsen, associate professor at Aarhus University.

Researchers from Germany's Alfred Wegener Institute and the University of Kansas in the United States were also part of the team. They flew over the glacier and used an ice radar to map the crater.