Saturday , October 23 2021

They found under the ice Greenland crater that produced asteroids


Only with its dimensions is it historic. These are the 25 largest found on the planet

They found under the ice Greenland crater that produced asteroids

Rocky topographic maps under the ice sheet and ice-free land surrounding the crater / The Natural History Museum of Denmark

In 2015, geochemists at the University of Copenhagen, Kurt Kjaer, saw a strange depression under the Hiawatha Greenland Glacier. A recent study revealed that what he had just discovered was a collision crater that was more than 30 kilometers wide. Its origin: an asteroid.

Only with the dimensions of the crater has it been historically, being one of the 25 largest found on Earth. However, its history and origins are what really attract science. When and how do we assume the extraordinary impact on the continental ice sheet in Greenland?

Apparently not long ago, not at least in terms of the history of our planet since the meteorite was at least one kilometer wide that created it.

extraordinary proof

As Kjær explained: extraordinary discoveries require extraordinary evidence. We have more than a decade of radar survey data, a technique for looking through ice with which we build topographic maps on glaciers. That's how in 2015 we found a great circular depression under the layer. We soon learned that this was something special, but at the same time it was clear that it would be difficult to confirm the origin of depression.

continue his studies

Since then, the last three years have been working and studying the area, taking pictures 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 cannot be seen through the aircraft window. It's funny that until now no one has thought: "Hey, is that a semi-circular feature there?" From the plane it's smooth and hard to see, unless you already know it's there.

By using satellite imagery taken with a low sun angle that accentuates hills and valleys on the plains of the ice sheet, you can really see the entire circle of craters in these images.

Kjaer also explained that the stranger reminded him from the start to the Cape York meteor that had fallen in Greenland about 10,000 years ago, the same which left large pieces of iron scattered in the same area as the glaciers, could there be any connection with that? impact event?

The recently published work failed to conclude that this was the case, but they present several lines of convincing evidence that show that craters may have formed over the past 100,000 years.

Geochemical analysis of sediments near the glacier also shows evidence of the process of impact, indicating the presence of iron. These include quartz, which is usually found in impact zones, and glass, which is made from silica in bedrock by intense heat from impact.

In terms of age, researchers believe that the evidence they provided was strong enough to think that it happened before Greenland covered itself with ice.

It is difficult to err if we think that the range spanned 3 million years ago to only 12 thousand years ago, towards the end of the last ice age. According to Kjær: I think that happens when Greenland is covered in ice and therefore melts a large amount of melt water. This melting water will head south towards a sensitive point in the climate system.

they want to know the exact date of the impact

However, they are currently trying to drill ice to get a bedrock sample that can be used for dating and the exact date of impact.

A crater the size of a window that he opened for science. His study raises all kinds of questions, such as the possibility of asteroid rain or the fact that the impact causes global cooling events that can greatly affect early human populations.

Source link