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Oldest, largest impact crater is in Greenland

08/07/2012
English: Barringer Meteor Crater in Arizona.

English: Barringer Meteor Crater in Arizona. (Photo credit: Wikipedia)

The crater was discovered near the Maniitsoq region of West Greenland by a team of scientists from the Geological Survey of Denmark and Greenland (GEUS) in Copenhagen, Cardiff University in Wales, Lund University in Sweden and the Institute of Planetary Science in Moscow.

The crater is 100 kilometers wide and is the result of an asteroid or comet impact.

The previously oldest known crater on Earth formed 2 billion years ago and the chances of finding an even older impact were thought to be, literally, astronomically low.

“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 Cardiff University’s School of Earth and Ocean Sciences, who was part of the team.

Finding the evidence was made all the harder because there is no obvious bowl-shaped crater left to find. Over the 3 billion years since the impact, the land has been eroded down to expose deeper crust 25 km below the original surface. All external parts of the impact structure have been removed, but the effects of the intense impact shock wave penetrated deep into the crust.

The impact crater currently measures about 62 miles (100 kilometers) from one side to another. But before it eroded, it was likely more than 310 miles (500 km) wide.

The team has calculated it was caused by a meteorite 19 miles (30 km) wide, which, if it hit Earth today, would wipe out all higher life.

John Spray, a meteorite expert at the University of New Brunswick, who wasn’t involved in the research, said he thinks it’s probably a meteor crater, but points out that it hasn’t been proved, and may not be for some time. “It’s very interesting and it’s good science,” he said. “But we don’t really know how to recognize very old impact craters, because they are typically so highly modified.”

These impacts are of interest to mining companies not because of the large meteorites themselves — they typically vaporize — but because of the effect upon the Earth’s surface. The impact heats rocks so much that metals can melt and then collect toward the bottom of the crater. Craters can also be important sources of oil and gas; the crushed, permeable rocks can act like a sponge, absorbing hydrocarbons.
»Ancient Asteroid Crater Discovered

»Greenland is home of oldest, largest impact crater

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