It's hard to find out what might be a massive impact crater deep under Greenland's ice sheet, scientists believe they may have found a second, unrelated structure nearby.
The new crater with a suspicious blow is about 36 kilometers wide and the first structure is not yet definitively identified as a crater. On Earth there are many more elements shaped like craters than the actual craters formed by meteorites that are stuck in the planet.
"I started to ask myself," Is that it? more crater? Are the underlying data supporting this idea? "Chief author Joe McGregor, a NASA space scientist at Greenbelt, USA, said in a statement. "Help in identifying a big crater under the ice was already very exciting, but now it seemed that there might be two of them. [In Pictures: The Giant Crater Beneath Greenland Explained]
McGregor is also involved in identifying a slightly smaller impact crater called Hiawatha, which was announced in November. In addition to its striking circular shape and the heights of the edge and the central mound, which scientists expect in a crater of crack, the discovery in Haiawa also sports minerals that seem to have been suddenly shocked by a dramatic event like a meteorite.
The new candidate does not have a similar mineral footprint and is believed to be a meteor based solely on altitude data collected from 11 different remote observation programs. These data show a striking break in the surface of the Earth about 183 km southeast of the location of the first structure. The second structure is less round than Hiawatha, but scientists believe they have noticed the same distinctive edges and inner peaks.
Despite the closeness of the two characteristics, scientists believe that even if both are formed by meteorites that have plagued the Earth, they are likely to be created separately. The team believes that the newly discovered structure, formed more than 79,000 years ago, before any of the ice that is over it is in place.
This, however, leaves a wide range of potential ages, so the team added a second technique to try to estimate its age. By modeling what kind of impact crater it might have looked like when it was created, scientists have been able to calculate how many thousands of years ice erosion would be needed to create its current form. This process implies that the structure was first formed between 100,000 and 100 million years.
This range appears to be older than the structure of Hiawatha, originally dated between 3 million and 12,000 years ago; Researchers on this project suspect that the alleged crater is from the younger side of this range.
Both potential craters need to be checked before scientists can tell something about the history of the meteorites that crash into the Earth. But the team obviously still enjoys the innovations in studying these massive structures hidden deep under the ice – in this case worth more than a mile (2 km).
"We have explored Earth in many different ways, from land, air and space – it is exciting that such discoveries are still possible," McGregor said.
The study is described in an article published today (11 February) in the magazine Geophysical studies,
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