A meteorite 100 times larger than the dinosaur-killing space rock may have been the basis for early microbial life

New research suggests that the destruction of a giant meteorite impact on early Earth may have allowed life to flourish.

A study of the remains of a 3.26 billion-year-old impact shows that microbial life – the only form of life at the time – may have ultimately benefited from the impact of a meteorite 50 to 200 times larger one that wiped out the Nonavian dinosaurs. While there was destruction immediately after the impact, the meteorite and a resulting tsunami eventually released nutrients that were critical to microbes, the researchers reported.

“Not only are we finding that life is resilient because we are still finding evidence of life after the impact; we actually believe there have been changes in the environment that have been really great for life,” he said Nadia DrabonAssistant professor of earth and planetary sciences at Harvard University and lead author of the study, published Oct. 21 in the journal PNAS.

Drabon and her colleagues examined evidence of an impact during the Archean (4 to 2.5 billion years ago) in what is now South Africa. At that time, this region was a shallow marine environment. “There are probably few places on Earth where rocks this old preserve a moment in time in such detail,” Drabon told Live Science.

Researchers can see spherules in the layers – tiny, glass-like spheres that are formed when a meteorite impact melts silicon-containing rock. You will also see conglomerates, or stones made up of other rocks. The conglomerates are evidence of a globe-spanning tsunami that tore up the ocean floor and crushed the debris into clumps. The chemistry of the rock layers reveals remnants of the meteor itself, which was a primitive type of space rock called a carbonaceous chondrite. It would have been between 23 and 36 miles (37 to 58 kilometers) in diameter.

Although the location in South Africa was far from the impact, the collision had significant consequences. Not only did it cause a global tsunami, but it also kicked up dust that would have been wiped out the sun. Evaporated minerals show that the impact also heated the atmosphere so much that the upper layers of the ocean boiled.

“It would have been pretty catastrophic for any life on land or in shallow water,” Drabon said.

Deposits on this rock reflect a tsunami caused by a meteorite impact 3.26 billion years ago. (Image credit: Nadja Drabon)

However, a few years or decades after the impact, life returned, and it may have been in better condition than ever before. That's because there were spikes in vital elements after the impact, the study authors noted in the study.

The first was phosphorus, a vital mineral that would likely have been in short supply in the oceans 3.26 billion years ago. Today, phosphorus erodes from continental rocks into the oceans, but during the Archean Earth was largely a water world with a limited number of volcanic islands and small continents. A carbonaceous chondrite the size of the impactor would have contained hundreds of gigatons of phosphorus, Drabon said.

The second was iron, which would have been abundant in the deep oceans of the Archean but not in the shallow seas. The tsunami caused by the meteorite impact would have mixed the oceans and brought this metal to shallower regions, Drabon said. Red rock in the layers above the impact shows this change in the environment.

The study helps explain how life began to flourish on a young planet hit by space collisions. The geological record suggests that meteorites larger than the one that killed the dinosaurs struck the early Earth at least every 15 million years. Life is resilient, Drabon said, but these impacts may have influenced life's evolution each time they occurred.

“Because of the extinction of the dinosaurs, mammals were able to shine, and who knows if we could live without that?” Drabon said. Archaic influences may have had similarly crucial effects on the types of microbes that thrived and the species that disappeared.

“Any impact will have some negative impacts and some positive impacts,” Drabon said.

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