About 12,000 years ago, something burned a large swath of the Atacama Desert in northern Chile. The heat was so intense that it turned the sandy soil into large slabs of silicate glass. Now a research team has come to a conclusion about the cause of this hell that covered the Atacama Desert with crystals. As published in the magazine ‘geology’It was the impact of a comet.
Researchers have noticed that the desert glass samples contain small fragments of minerals often found in rocks of extraterrestrial origin. These minerals correspond to the composition of the material sent back to Earth by the mission. Stardust NASA, which sampled particles from a comet called Wild 2. The team concludes that these mineral assemblages are likely the remains of an extraterrestrial object, most likely a comet with a composition. similar to Wild 2, whose explosion melted the sandy surface below.
crystals on earth
“This is the first time we have clear evidence of crystals on Earth that were created by thermal radiation and winds from a fireball that exploded just above the surface.”says Pete Schultz, a professor at Brown University. “To have such a drastic effect over such a large area, it was a really massive explosion. that.”.
The crystals are concentrated in patches throughout the Atacama Desert east of Pampa del Tamarugal, a plateau in northern Chile located between the Andes Mountains to the east and the Chilean Coast Range to the west. Fields of dark green or black glass are in a corridor that stretches for about 75 kilometers. There’s no evidence the crystals could have been created by volcanic activity, Schultz says, so their origin has been a mystery until now.
Tornado Force Winds
Some scholars have postulated that the glass was the result of ancient grass fires, as the area was not always a desert. In the Pleistocene era there was an oasis with trees and grassy wetlands created by the rivers that stretched from the mountains to the east. It has been suggested that widespread fires may have burned enough to melt sandy soil into large glassy slabs.
But the amount of glass present as well as several key physical characteristics make simple fires an impossible formation mechanism. The crystals show evidence of being twisted, bent, rolled and even thrown while still in molten form. This corresponds to a large explosion of an incoming meteorite, which would have been accompanied by tornado-force winds.
Working with researchers from the Fernbank Science Center in Georgia, Universidad Santo Tomás in Chile, and Chile’s Geology and Mining Service, Schultz and his colleagues performed detailed chemical analysis of dozens of samples taken from the glass deposits throughout the region.
The analysis found minerals called zircons that had thermally broken down to form baddeleyite. This mineral transition typically occurs at temperatures above about 1,650 degrees Celsius, much hotter than what might be generated by grass fires.
The analysis also revealed assemblages of exotic minerals found only in meteorites and other extraterrestrial rocks. Specific minerals such as cubanite, troilite, and inclusions rich in calcium and aluminum matched the mineral signatures of cometary samples recovered during NASA’s Stardust mission.
“These minerals are what tell us that this object has all the marks of a comet”says Scott Harris, planetary geologist at the Fernbank Science Center and co-author of the study. “Having the same mineralogy that we’ve seen in the Stardust samples in these crystals is really powerful evidence that what we’re seeing is the result of a comet explosion.”. Although the researchers acknowledge that more work is needed to establish the exact age of these crystals, Schultz believes the impact coincides in time with the disappearance of large mammals from the area.
“It is too early to say whether there was a causal link or not, but what we can say is that this event happened around the same time as when we think the megafauna have gone, which is intriguing.”he specifies. “It is also possible that this was observed by the first inhabitants who had just arrived in the area. It would have been quite a sight,” he adds. The team also hopes to collect more data to find out the size of the impactor. In addition, he thinks this study could help identify similar explosion sites. somewhere else.
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Reference article: https://www.abc.es/ciencia/abci-misterio-crystal-cubre-desierto-atacama-202111090106_noticia.html#ancla_comentarios