Around 12,000 years ago, something torched a broad section of Chile’s the Atacama Desert with heat so intense that it converted the sandy soil into massive slabs of silicate glass. A research team investigating the distribution and content of those glasses has now determined what triggered the flames.
Researchers reveal that samples of desert glass include microscopic particles of minerals often seen in extraterrestrial rocks in a study published in the journal Geology. The minerals are close to the formation of material recovered to Earth by NASA’s Stardust mission, which accumulated particles from the comet named Wild 2.
According to the research, the mineral assemblages are most likely the remnants of an extraterrestrial object, most likely a comet with a composition similar to Wild 2, that fell after the explosion that melted the sandy surface.
According to Pete Schultz, a professor at Brown University, this is the first time we have unambiguous evidence of glasses on Earth formed by heat radiation and winds from a fireball erupting close above the surface. This was a tremendously big explosion, having such a dramatic effect over such a vast region. Many of us have seen bolide fireballs race across the sky, but they are little blips in comparison.
The glasses may be found in pieces in the Atacama Desert, a plateau in northern Chile located between the Andes Mountains to the east. A 75-kilometer-long route has fields of dark green or black glass. According to Schultz, there is no indication that the glasses were formed by volcanic activity, therefore their origin remains unknown.
Some scholars believe that the glass formed as a consequence of ancient grass fires, as the area was not always dessert. During the Pleistocene period, rivers stretching from mountains to the east produced an oasis with trees and green wetlands, and it’s been proposed that widespread fires burned hot enough to melt the sandy soil into big glassy slabs.
However, because of the amount of glass present, as well as numerous crucial physical features, simple fires are an impossible production method, according to the new research. While still molten, the glasses have been twisted, folded, rolled, and even tossed. This is constant with a massive meteor that is an airburst explosion, as well as tornado-force winds.
According to Schultz, the mineralogy of the glass puts even more significant doubt on the grassfire theory. Schultz and colleagues conducted a rigorous chemical study of hundreds of samples gathered from glass formations around the region with few other researchers.
The examination discovered zircon minerals that had thermally disintegrated to generate baddeleyite. According to Schultz, that mineral transformation normally occurs at temperatures over 3,000 degrees Fahrenheit, which is significantly higher than what could be created by grass fires.
According to the researchers, the examination also revealed assemblages of unusual minerals found exclusively in meteorites and other alien rocks. Mineral fingerprints from comet samples recovered by NASA’s Stardust mission were matched by specific minerals such as cubanite, troilite, and calcium-aluminum-rich inclusions.
“Those minerals are what tell us that this object has all the hallmarks of a comet,” Scott Harris explained. The presence of the identical mineralogy seen in the Stardust samples entrained in these glasses is very strong proof that what we’re witnessing is the product of a cometary airburst.
