Widespread glasses generated by cometary fireballs during the late Pleistocene in the Atacama Desert, Chile

Twisted and folded silicate glasses (up to 50 cm across) concentrated in certain areas across the Atacama Desert near Pica (northern Chile) indicate nearly simultaneous (seconds to minutes) intense airbursts close to Earth's surface near the end of the Pleistocene. The evidence includes mineral decompositions that require ultrahigh temperatures, dynamic modes of emplacement for the glasses, and entrained meteoritic dust. Thousands of identical meteoritic grains trapped in these glasses show compositions and assemblages that resemble those found exclusively in comets and CI group primitive chondrites. Combined with the broad distribution of the glasses, the Pica glasses provide the first clear evidence for a cometary body (or bodies) exploding at a low altitude. This occurred soon after the arrival of proto-Archaic hunter-gatherers and around the time of rapid climate change in the Southern Hemisphere.

Automated summary

The twisted and folded silicate glasses found near Pica in the Atacama Desert suggest intense airbursts close to Earth's surface in the Pleistocene. The evidence includes high temperatures, dynamic modes of emplacement, and meteoritic dust entrained in the glasses. The trapped meteoritic grains resemble those found in comets and primitive chondrites, providing clear evidence for a low-altitude cometary body explosion.