An ice survey in Greenland has revealed evidence of the effect of an iron asteroid on an island, perhaps only 12,000 years ago.The crater, resulting from a 30-kilometer-wide collision, is currently hidden under a layer of ice of 800 meters thickness.
It was recently introduced by an ultra-wide-band radar system developed in the Ice sensing remote sensing center (CReSIS) in the United States at the University of Kansas (KU). As a result of the action under the Hiawatha glacier in the far northwest of Greenland, the characteristics of the crater are described in & # 39; Scientific Advances & # 39; in an article published in the section.
It was associated with data collected by the KU between 1997 and 2014 for the Regional North Pole Climate Review and the NASA Program for the IceBridge operation, and was supported in May 2016 with more data collected using consistent multi-channel probe radar. The depth developed in KU (MCoRDS).
"We've collected a large amount of radar survey data over the last two decades, and gliologists have gathered this information to produce maps of how Greenland is under the ice," says John Paden, an electrical engineering and science professor. Calculations in the joint scientist in KU & CReSIS.
The Danish researchers were looking at the map, and they saw this massive collapse resembling a satellite beneath the ice sheet and observed satellite imagery. Since the crater is on the edge of the ice sheet, you can see a circular pattern there as well. Based on this discovery, a detailed radar study was conducted in May 2016 using a new modern radar designed and built by KU for the Alfred Wegener Institute in Germany.
Helping to develop MCoRDS radar signal processing software, Paden has participated in low-altitude flights in a grid layout in the impact crater to detail their size.
Da You can see the round structure on the edge of the ice sheet, especially when you fly high enough, “he says. For the most part, the crater cannot be seen through the aircraft window. Using the satellite imagery taken with a low angle of sun, emphasizing the hills and valleys in the terrain of the ice sheet, you can really see the entire crater circle in these images. "
To validate satellite and radar findings, the research team conducted more groundwork on the glycofluvial precipitation of the larger river draining the crater. The study showed the existence of glass-like "impact quartz and other grains". The research team believes that these rocks and glassy particles can be produced from collision fusion of the grains in the metasedimentary bedrock.
Set impact date
The study continues to determine the effect of the asteroid in Greenland more precisely. The authors say this There is evidence that the Hiawatha impact crater occurred during the Pleistocene, Because this age is more consistent with the implications of the data that is currently available. However, over time this wide range remains "unclear". The team to the southwest of the crater has found a region rich in potential debris from the impact range, which can help reduce the date range.
Di The climate and atmosphere would reflect the debris into the atmosphere that would affect the potential to melt too much ice, so there could be a sudden fresh water stream that would affect the flow of the ocean in the Nares Strait between Canada and Greenland. "Paden argues. The evidence suggests that the effect occurred after the formation of the Greenland ice sheet, but that the research team is still working on a definite date."
According to planetary geologist David Tovar, The discovery of the crater in Greenland suggests that the planet has several regions that can still maintain evidence of impact craters. "Most of the time, these structures are not taken into account by geologists because of the lack of information about the training processes and the type of materials left by the asteroid effects in different rock types," he says. .
Tır Similarly, iniz he continues, ı it is clear that the work that corresponds to the acquisition of remote sensing data (satellite imagery, aerial photographs, geophysics) is very helpful when you want to examine the multiply structures covered under some kind of material; In this particular case, the ice. "
Tovar draws attention to this This study should be completed with field visits, which should be gathered evidence in hand specimens of knowledgeable scientists in planetary geology. "That is the example of rocks with typical structures produced by effects, mega, macro and microscopic, which is the ultimate aim of combining key proofs at different scales, which will be analyzed later in the laboratory.