Just because of its dimensions is historical. It is among the 25 largest found on the planet
In 2015, Copenhagen University geochemist Kurt Kjær noticed a strange depression beneath the Greenland Hiawatha glacier. A study now reveals that what he had just found was an impact crater more than 30 kilometers wide. Its origin: an asteroid.
Only by its dimensions the crater is already historical, being one of the 25 largest found in the Earth. However, the story and the origin of it is what really matters to science. When and how do we assume a tremendous impact on the continental ice sheet in Greenland?
It turns out not so long ago, not at least in terms of the history of our planet since a meteorite at least a kilometer wide has created it.
As Kjær explained: extraordinary discoveries require extraordinary evidence. We have more than a decade of radar research data, a technique to look through the ice with which we construct a map of the topography on the glacier. That is how in 2015 we came across the great circular depression below the layer. We immediately knew that this was something special, but at the same time it was clear that it would be difficult to confirm the origin of the depression.
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Since then, the last three years have worked and studied the area, taking photos and using a new radar developed by the University of Kansas.
You can see the rounded structure at the edge of the ice sheet, especially when flying high enough. For the most part, the crater can not be seen through the airplane window. It's funny that so far no one thought: "Hey, what's this semicircular feature there?" The plane is subtle and hard to see, unless you already know it's there.
Using satellite images taken at a low angle of sunshine that accentuates the hills and valleys on the ice sheet terrain, you can see the circle of the entire crater in these images.
Kjær also explained that the stranger remembered him from the beginning of the Cape York meteor, which fell in Greenland about 10,000 years ago, the same that left huge pieces of iron scattered in the same region as the glacier, there could be a link to it ? impact event?
The recently published work does not conclude that this is the case, but they do present several compelling lines of evidence suggesting that the crater probably formed over the last 100,000 years.
The geochemical analysis of sediments near the glacier also showed evidence of impact processes, indicating the presence of iron. These included quartz, which is commonly found in impact zones, and glass, which is created from silica in the bed rock by the intense heat of the impact.
In terms of age, the researchers believe the evidence they provide is strong enough to think that this happened before Greenland covered itself with ice.
It's hard to be wrong to think that the track ranges from 3 million years ago to just 12,000 years ago at the end of the last ice age. According to Kjær: I think it happened when Greenland was covered in ice and therefore would have melted a significant amount of molten water. This melted water will move south toward a sensitive point in the climate system.
they want to know the exact date of the impact
However, they are currently trying to drill the ice to get samples of the rock that can be used for accurate dating and impact date.
A crater the size of the window he opened for science. Their study raises all sorts of issues such as the possibility of a rain of asteroids or the fact that the impact caused a global cooling event that could greatly affect the ancient populations of humans.