Meteorite Carved Huge Greenland Crater 58 Million Years Ago, Study Says

WASHINGTON, March 9 (Reuters) – A huge crater in northwest Greenland, buried under a thick sheet of ice and first spotted in 2015, is much older than previously suspected – formed by a meteorite impact 58 million years ago, rather than 13,000 years ago as had been proposed.

Scientists said on Wednesday they used two different dating methods on sand and rock left behind by the impact to determine when the crater – about 31 km wide – formed. They found the meteorite – around 1.5-2km across – hit Greenland around 8 million years after a larger asteroid impact on Mexico’s Yucatan Peninsula wiped out the dinosaurs .

The crater lies beneath Greenland’s Hiawatha Glacier, covered by an ice cap six-tenths of a mile (1 km) deep. It had gone undetected until airborne radar data penetrating the ice informed scientists of its existence.

It is one of the 25 largest known impact craters on Earth. Over the eons, Earth has been hit by space rocks countless times, though gradual changes to the planet’s surface have erased or obscured many craters.

Greenland back then – in the Paleocene era – was not the icy place it is today, and was instead covered in temperate rainforests populated by a variety of trees and inhabited by some of the mammals that became Earth’s dominant land animals after the dinosaurs – aside from their bird descendants – became extinct.

The meteorite released millions of times more energy than an atomic bomb, leaving a crater large enough to engulf the city of Washington.

“The impact would have devastated the local area,” said Swedish Museum of Natural History geologist Gavin Kenny, lead author of the research published in the journal. Scientists progress.

“The air blast from the impact would have toppled most trees for tens to hundreds of miles, and the thermal blast from the impact would have ignited trees up to hundreds of miles from the impact site. , starting huge wildfires,” Kenny added. .

The impact would also have triggered regional earthquake tremors as ash from wildfires and molten dust and rock that had been violently ejected into the atmosphere would have rained down, producing a thick blanket of debris, Kenny said.

Serious as it is, it hasn’t approached the scale of the calamity wrought by the asteroid – estimated to be 12km wide – which struck 66 million years ago, wiping out three-quarters of species from Earth and triggering a global climate catastrophe.

“It is not yet known whether the impact had a lasting effect on global climate, but unlikely in my opinion,” said geology professor and study co-author Michael Storey of the Natural History Museum. from Denmark.

Some scientists had speculated that the impact happened after the Greenland Ice Sheet formed 2.6 million years ago and possibly even as recently as around 13,000 years ago. to initiate a documented cold period.

The researchers used two dating methods based on radioactive decay – the transformation of atoms of one element into atoms of another element. Because the ice-covered crater is inaccessible, they tested sand from rocks superheated by the impact and minerals called shocked zircons contained in pebbles – all recovered from a river carrying material from the crater out of the glacier. Both methods gave the same age results.

“Thus, the impact did not occur – or cause a climate change event – in the time of humans as previously proposed and speculated,” Kenny said.

“Impacts of this size only happen every few million years, so we don’t have to worry about an impact like this happening anytime soon,” Kenny added.

Reporting by Will Dunham, editing by Rosalba O’Brien

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