A Massive comet exploding over Chile 12,000 years ago may have created strange glassy rocks
A 75-kilometre (47-mile) swath of desert is strewn with strange, dark, glassy rocks that have long puzzled scientists. New research finds that those rocks are quite similar to comet particles collected by a NASA mission called Stardust. The scientists behind the work think that all those years ago, one or more huge comets exploded together in the skies over the region, causing tornadoforce winds, scorching the grassy landscape and scattering the area with warped and twisted glass that still contains minerals generally found only in meteorites. “This is the first time we have clear evidence of glasses on Earth that were created by the thermal radiation and winds from a fireball exploding just above the surface,” said Pete Schultz, a geologist at Brown University.
Schultz and his colleagues collected 300 pieces of the strange glassy rock to analyse from two patches of the region. In addition, the team cut thin, polished slices out of 20 of those samples to study under a microscope. In all of those slices, the researchers found dozens of grains and fragments that didn’t match the region.
Those anomalies include a mineral called troilite, which is typically found in meteorites, and decomposed zircons, suggesting that the samples reached temperatures hotter than 1,670 degrees Celsius (3,000 degrees Fahrenheit). Scientists can’t yet precisely date the glassy rocks, although other research on the phenomenon has suggested the strange rocks formed between 12,300 and 11,500 years ago.