Deposits of dark silicate glass are scattered throughout a 75-kilometer passage in the Atacama Desert in northern Chile. New research study reveals that those glasses were most likely formed by the heat of an ancient comet blowing up above the surface. Credit: P.H. Schultz/Brown University
” This is the very first time we have clear evidence of glasses in the world that were created by the thermal radiation and winds from a fireball blowing up simply above the surface area,” stated Pete Schultz, a teacher emeritus in Brown Universitys Department of Earth, Environmental and Planetary Sciences. “To have such a significant impact on such a big location, this was a really huge surge. Great deals of us have seen bolide fireballs streaking throughout the sky, but those are tiny blips compared to this.”
The glasses are focused in spots across the Atacama Desert east of Pampa del Tamarugal, a plateau in northern Chile nestled in between the Andes Mountains to the east and the Chilean Coastal Range to the west. Fields of dark green or black glass take place within a corridor extending about 75 kilometers. Theres no evidence that the glasses might have been produced by volcanic activity, Schultz says, so their origin has been a secret.
Some researchers have actually presumed that the glass arised from ancient yard fires, as the area wasnt constantly desert. Throughout the Pleistocene epoch, there were oases with trees and grassy wetlands developed by rivers extending from mountains to the east, and its been recommended that prevalent fires may have burned hot enough to melt the sandy soil into large glassy pieces.
Analysis of the glass samples revealed a mineralogy that followed a cometary origin. Credit: P.H. Schultz/Brown University
However the amount of glass present together with a number of crucial physical characteristics make basic fires a difficult formation mechanism, the new research study found. The glasses reveal proof of having actually been twisted, folded, rolled, and even tossed while still in molten kind. Thats constant with a large incoming meteor and airburst explosion, which would have been accompanied by tornado-force winds. The mineralogy of the glass casts further serious doubt on the grassfire concept, Schultz states. Along with researchers from the Fernbank Science Center in Georgia, Chiles Universidad Santo Tomás and the Chilean Geology and Mining Service, Schultz and coworkers performed a comprehensive chemical analysis of lots of samples drawn from glass deposits across the area.
The analysis discovered minerals called zircons that had actually thermally disintegrated to form baddeleyite. That mineral shift usually happens in temperatures in excess of 3,000 degrees Fahrenheit– far hotter than what could be generated by grass fires, Schultz states.
The analysis likewise showed up assemblages of exotic minerals only found in meteorites and other extraterrestrial rocks, the scientists state. Particular minerals like cubanite, troilite, and calcium-aluminum-rich additions matched mineral signatures from comet samples recovered from NASAs Stardust objective.
” Those minerals are what inform us that this item has all the markings of a comet,” said Scott Harris, a planetary geologist at the Fernbank Science Center and study co-author. “To have the same mineralogy we saw in the Stardust samples entrained in these glasses is really powerful proof that what were seeing is the outcome of a cometary airburst.”
More work needs to be done to develop the specific ages of the glass, which would figure out exactly when the event took place, Schultz says. The tentative dating puts the effect right around the time that big mammals vanished from the area.
” Its prematurely to state if there was a causal connection or not, however what we can state is that this event did take place around the exact same time as when we believe the megafauna vanished, which is intriguing,” Schultz said. “Theres also a chance that this was actually witnessed by early residents, who had simply shown up in the region. It would have been quite a show.”
Schultz and his team hope that additional research study may help to constrain the timing and shed light on the size of the impactor. In the meantime, Schultz hopes this study may help researchers determine comparable blast websites elsewhere and expose the prospective danger postured by such events.
” There may be lots of these blast scars out there, however till now we have not had sufficient proof to make us believe they were really associated to airburst events,” Schultz said. “I think this website offers a template to assist improve our impact designs and will assist to recognize similar websites in other places.”
Referral: “Widespread glasses created by cometary fireballs throughout the late Pleistocene in the Atacama Desert, Chile” by Peter H. Schultz, R. Scott Harris, Sebastián Perroud, Nicolas Blanco and Andrew J. Tomlinson, 2 November 2021, Geology.DOI: 10.1130/ G49426.1.
Other authors of the study were Sebastian Perroud, Nicolas Blanco, and Andrew Tomlinson.
Deposits of dark silicate glass are strewn across a 75-kilometer passage in the Atacama Desert in northern Chile. New research shows that those glasses were likely formed by the heat of an ancient comet blowing up above the surface. Credit: P.H. Schultz/Brown University
Heat from a comet exploding just above the ground fused the sandy soil into spots of glass stretching 75 kilometers, a study led by Brown University scientists found.
Around 12,000 years back, something blistered a huge swath of the Atacama Desert in Chile with heat so intense that it turned the sandy soil into prevalent pieces of silicate glass. Now, a research team studying the circulation and structure of those glasses has actually come to a conclusion about what caused the inferno.
In a research study published in the journal Geology, researchers show that samples of the desert glass consist of tiny fragments with minerals typically found in rocks of extraterrestrial origin. Those minerals carefully match the structure of material returned to Earth by NASAs Stardust mission, which tested the particles from a comet called Wild 2. The team concludes that those mineral assemblages are most likely the remains of an extraterrestrial object– more than likely a comet with a composition comparable to Wild 2– that streamed down after the explosion that melted the sandy surface listed below.
In a research study published in the journal Geology, researchers show that samples of the desert glass include tiny pieces with minerals often discovered in rocks of extraterrestrial origin.” This is the very first time we have clear proof of glasses on Earth that were developed by the thermal radiation and winds from a fireball blowing up just above the surface area,” said Pete Schultz, a professor emeritus in Brown Universitys Department of Earth, Environmental and Planetary Sciences. Theres no evidence that the glasses might have been created by volcanic activity, Schultz states, so their origin has been a mystery.
The mineralogy of the glass casts even more serious doubt on the grassfire concept, Schultz says. Along with scientists from the Fernbank Science Center in Georgia, Chiles Universidad Santo Tomás and the Chilean Geology and Mining Service, Schultz and associates carried out a comprehensive chemical analysis of dozens of samples taken from glass deposits across the area.