(ORDO NEWS) — They first came to the attention of scientists about ten years ago: a mysterious field of glass fragments scattered across the Chilean Atacama Desert and built into a vast corridor 75 kilometers long.
These strange pieces of glass, which are too numerous to count, are clustered in several places along a deserted corridor and come in various shapes, some of them appearing as large slabs up to 50 centimeters across.
They have both rough and smooth features and look like they were somehow folded and twisted to give them their current shape, the scientists say.
“Many of them have morphologies that are indicative of sliding, shearing, twisting, rolling and folding (in some cases more than twice) before they have been fully tempered,” researchers explain in a new glass analysis study led by the first author. and planetary geologist Peter Schultz, professor emeritus at Brown University, Rhode Island.
What exactly caused these violent, chaotic transformations about 12,000 years ago has not been fully understood.
According to an early hypothesis, they could have appeared as a result of the explosion of a large meteor in the atmosphere – a giant air flare threw fragments of red-hot space rock onto the desert surface, and extraterrestrial shrapnel melted sand and soil in place.
This is not as far-fetched as it might seem at first glance. Similar mysterious glass remnants have been found in many places around the planet, and in many cases meteorite explosions or impacts are regarded as the most likely explanation for how the glass got there.
Not that space rocks are the only hypothetical argument to consider. In the case of the glass shards of the Atacama, scientists have also speculated that they may have formed in the furnace of natural fires on the surface, in a different era and in a different climate, when the desert was covered with more abundant vegetation.
So what is it?
According to Schultz and his colleagues, the extraterrestrial space rock hypothesis is the more likely explanation.
In the new study, the scientists collected and studied more than 300 desert glass samples by examining them under an electron microscope and analyzing their chemical composition using spectroscopy.
The results, according to the team, clearly indicate that the glass does not entirely belong to our planet .
“This is the first time we have clear evidence that there are glasses on Earth that were formed under the influence of thermal radiation and wind from a fireball that exploded just above the surface,” says Schultz.
The minerals in the glass, called zircons, decomposed to form the mineral baddeleyite, which would require extremely high temperatures of over 1,670°C, much hotter than a wildfire, the researchers said.
But that’s not all. The glass fragments also contained thousands of grains of exotic minerals that are rare on Earth; they are so rare that they are only known in meteorites and other extraterrestrial rocks.
Some of these strange minerals, including extraterrestrial cubanite , were previously identified by NASA’s Stardust mission, which collected samples from comet Wild 2 in 2004.
It’s too early to say for sure, but whatever the long- vanished object that created these strange fields of glass in the Atacama Desert , it could have had something to do with Wild 2, at least in its composition.
Another coincidence that merits further study is that the timing of this airburst broadly coincides with the extinction of Quaternary megafauna in South America , which itself coincided with both the arrival of ancient hunter-gatherers in the area and changes climate.
As to whether the meteor explosion could have been related to this extinction, it is not yet clear.
“It’s still too early to tell if there was a causal relationship or not,” says Schultz. “But we can say that this event happened around the same time that we think the megafauna disappeared, and that’s intriguing .”
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