A meteorite 100 times bigger than the space rock that kills dinosaurs may have fueled early microbial life

On November 3, 2024By Pranco

New research suggests that the devastation 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 type of life at the time – may have ultimately benefited from a meteorite impact 50 to 200 times larger than a meteorite impact . one that wiped out the non-avian dinosaurs. While devastation reigned immediately after the impact, the meteorite and resulting tsunami ultimately released nutrients crucial to microbes, the researchers reported.

“Not only are we discovering that life has resilience because we’re still finding evidence of life after the impact; we even think there may have been changes in the environment that were really great for life,” said Nadja Drabonan assistant professor of earth and planetary sciences at Harvard University and the lead author of the study, published Oct. 21 in the journal PNAS.

Drabon and her colleagues examined evidence of an impact during the Archean era (4 billion to 2.5 billion years ago) in what is now South Africa. At the time, this region was a shallow marine environment. There are probably only a few places on Earth where rocks of this age are preserved in such detail, Drabon told LiveScience.

Within the layers, researchers can see globules: small, glassy spheres that form when a meteorite impact melts silica-containing rock. They also see conglomerates, or rocks made from other pieces of rock. The conglomerates are evidence of a global tsunami that tore up the seabed and smashed the debris into clumps. The chemistry of the rock layers reveals remnants of the meteor itself, a primitive type of space rock called carbonaceous chondrite. Its diameter would have been between 23 and 36 miles (37 to 58 kilometers).

Although the location in South Africa was a considerable distance from the impact, the collision had major consequences. Not only did it cause a global tsunami, but it also kicked up dust that would have been swept away the sun. Evaporated minerals show that the impact also heated the atmosphere enough to boil the upper layers of the ocean.

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

A close-up of a rock with deposits in it

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

However, within a few years or decades after the impact, life returned and was perhaps better than ever. That’s because after the impact there were spikes in elements essential to life, the study authors noted in the study.

The first was phosphorus, an essential mineral that would likely have been scarce in the oceans 3.26 billion years ago. Today, phosphorus is eroding 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 trapped hundreds of gigatons of phosphorus, Drabon said.

The second was iron, which would have been abundant in the deep Archean oceans, but not in the shallow seas. The tsunami caused by the meteorite impact would have mixed the oceans, bringing this metal into shallower areas, Drabon said. Red rocks in the layers above the impact show this change in the environment.

The study helps explain how life began to flourish on a young planet ravaged by collisions in space. Geological records show that meteorites larger than the ones that killed the dinosaurs hit the early Earth at least every 15 million years. Life was resilient, Drabon said, but those consequences could have affected the evolution of life each time they occurred.

“The extinction of the dinosaurs allowed mammals to radiate, and without that, who knows if we could be here?” said Drabon. The Archean influences may have had similarly decisive effects on the types of microbes that flourished and those that faded away.

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