World's oldest, largest meteorite crater found in Greenland

[Ann]

Scientists have found what appears to be the world's oldest and largest meteorite impact crater in Greenland. The meteorite, which hit the Earth three billion years ago, may have had a diameter of more than 30 kilometers and may have slammed into the Earth with a velocity of 20,000 kilometers per hour. If such a meteorite had hit the Earth today, most or all higher life forms would probably have been killed.

See this page, and, if you read Danish, read this. (And you can always try Google Translate! )

Ann

[bystander]

Oldest known impact crater found
Cardiff University | 2012 June 28

[SarasMusic]

WOW! I am always astonished when we find these new incredible findings. No matter how well we think we know the Earth we have yet to fully understand her. A 100 kilometre-wide...who would have thought that would have remained hidden for so long!

- Sara

[neufer]

Oldest Impact Crater on Earth Discovered in Greenland
Universe Today, John Williams, June 29, 2012

<<With shifting continents, rain, and wind, finding traces of ancient impact craters on Earth has been, literally, astronomically low. Now, an international team of scientists say they have found a massive impact crater in Greenland a billion years older than other known asteroid impact on Earth.

Scientists found the remains of the giant 100-kilometer wide crater near the Maniitsoq region of West Greenland and they believe it’s three billion years old. The largest and previously oldest known crater is the 300 kilometer-wide Vredefort crater in South Africa. “This single discovery means that we can study the effects of cratering on the Earth nearly a billion years further back in time than was possible before,” according to Dr. Iain McDonald of the School of Earth and Ocean Sciences at Cardiff University, who was part of the team.

Finding the crater wasn’t an easy task. Today, the Moon still shows marks of the massive bombardment that took place between three and four billion years ago. The early Earth, with its greater gravitational attraction, would have experienced even more collisions. But the land around Maniitsoq has been eroded over the eons to expose crust that originally was 25 kilometers below the surface. Effects of the immense shockwave produced on impact penetrated deep into the crust and remain visible. Evidence at that depth had never been observed before, says McDonald. “The process was rather like a Sherlock Holmes story,” said McDonald. “We eliminated the impossible in terms of any conventional terrestrial processes, and were left with a giant impact as the only explanation for all of the facts.”

• Sherlock Holmes [_A Scandal in Bohemia_]: “Once you eliminate the impossible,
  whatever remains, no matter how improbable, must be the truth.”"

Only about 180 impact craters have been discovered on Earth. Around 30 percent of them contain important natural resources, including nickel, gold, oil and natural gas. It was during an exploration of natural resources that evidence for the crater was discovered. “It has taken us nearly three years to convince our peers in the scientific community,” said McDonald. “But the mining industry was far more receptive. A Canadian exploration company has been using the impact model to explore for deposits of nickel and platinum metals at Maniitsoq since the autumn of 2011.” The international team, led by Adam Garde, a senior research scientist at the Geological Survey of Denmark and Greenland, or GEUS, contains members from Cardiff, Lund University in Sweden, and the Institute of Planetary Science in Moscow. Their work was recently published in the jounal Earth and Planetary Science Letters.>>

[astrotom]

Does anyone know if it is worth visiting that place? I always wanted to go to Greenland, yet never thought about a crater trip.

[Chris Peterson]

Does anyone know if it is worth visiting that place? I always wanted to go to Greenland, yet never thought about a crater trip.

Greenland is well worth visiting, although it can be a challenge. This crater, however, is undetectable visually, and was found by studying subtle geological and mineralogical characteristics of the rock.

[astrotom]

Ah right, thanks for the information.