On a young Earth, giant meteors might have been a harbinger of life, not death.
According to a recent study, life may have flourished on early Earth because of the destruction caused by a massive meteorite impact.
The impact of a meteorite 50–200 times greater than the one that wiped out the nonavian dinosaurs may have ultimately benefited microbial life, the only kind of life at the time, according to a study of the remains of an impact that occurred 3.26 billion years ago. The researchers noted that although there was immediate devastation following the impact, nutrients that were essential to bacteria were eventually released by the meteorite and the ensuing wave.
The lead author of the study, Nadja Drabon, an assistant professor of Earth and planetary sciences at Harvard University, stated, “Not only do we find that life has resilience because we still find evidence for life after the impact; we actually think there were changes in the environment that were really great for life.” The study was published in the journal PNAS on October 21.
In what is now South Africa, Drabon and her colleagues looked into evidence of an impact that occurred between 4 billion and 2.5 billion years ago during the Archean eon. This area was a shallow sea environment at the time. “Rocks this old probably only preserve a moment in such detail in a few places on Earth,” Drabon told Live Science.
Spherules, which are small, glass-like spheres that develop when silica-containing rock is melted by a meteorite impact, are visible to researchers in the layers. Conglomerates, or rocks composed of other rock fragments, are another sight they observe. A tsunami that ripped up the seafloor and smashed the debris into clumps is what caused the conglomerates. Remains of the meteor itself, a carbonaceous chondrite, a primordial kind of space rock, can be seen in the chemistry of the rock strata. Its diameter would have ranged from 23 to 36 miles (37 to 58 kilometers).
The impact had significant repercussions despite the South Africa site being a considerable distance away. It spewed up dust that would have blotted out the sun in addition to causing a global tsunami. The collision also heated the atmosphere sufficiently to boil the ocean’s upper layers, as evidenced by evaporating minerals.
“It would have been quite disastrous for any life on land or in shallow water,” stated Drabon.
However, life was returning within a few years or decades following the impact, and it might have been in better condition than before. According to the study’s authors, this is because there were increases in materials necessary for life after the impact.
The first one was phosphorous, a necessary mineral that was probably scarce in the seas 3.26 billion years ago. During the Archean, Earth was primarily a sea world with a few volcanic islands and small continents, but today, phosphorous erodes out of continental rocks into the oceans. According to Drabon, hundreds of gigatons of phosphorus would have been contained in a carbonaceous chondrite the size of the impactor.
The second was iron, which was scarce in the shallow seas but abundant in the deep Archean oceans. According to Drabon, this metal would have entered shallower areas as a result of the oceans being combined by the tsunami brought on by the meteorite strike. This environmental shift is seen in the red rocks found in the strata above the impact.
The discovery contributes to the understanding of how life emerged on a young planet plagued by space encounters. According to the geological record, the early Earth was struck by meteorites at least once every 15 million years that were larger than the one that wiped out the dinosaurs. According to Drabon, life was robust, but each time those effects happened, they might have influenced how life evolved.
Mammals were able to radiate because of the loss of the dinosaurs, and without that, it’s doubtful that we could still be here today.” “Said Drabon.” The types of bacteria that thrived and those that vanished might have been similarly influenced by the Archean events.
“Every impact is going to have some negative effects and some positive effects,” said Drabon.