Meteor impact 200 times larger than dinosaur killer spurred life

Billions of years ago, before life forms similar to today's appeared on Earth, our planet was regularly bombarded by meteorites. One of these impacts occurred 3.26 billion years ago, and geological evidence of this event has been found in rocks in the Republic of South Africa.

Nadja Drabon, a geologist from the Department of Earth and Planetary Sciences at Harvard University, and her team collected and analyzed rocks, studying their sedimentology, geochemistry, and carbon isotopic composition. The results of this research have been published, revealing the alleged sequence of events from over 3 billion years ago when an asteroid struck Earth.

This historical event, referred to as S2, is estimated to have been significantly larger than the object responsible for the extinction of the dinosaurs—up to 200 times larger. The S2 impact triggered a tsunami wave that mixed ocean waters and swept dust from the land into coastal areas.

The heat generated by the impact was also significant. It caused the surface of the ocean to boil and increased atmospheric temperature. A thick layer of dust covered the planet, preventing photosynthesis.

Despite this, bacteria quickly rebuilt their populations. There was also a rapid increase in the number of organisms feeding on phosphorus and iron. Iron could have been brought up from ocean depths, and phosphorus came from both the meteorite and increased land erosion.

Analyses conducted by Drabon indicate that bacteria with iron-based metabolism quickly thrived, which was a direct effect of the impact. This shift towards life forms that favored iron, although short-lived, may have had a crucial impact on the early stages of life's development on Earth.

"We think of impact events as being disastrous for life. But what this study is highlighting is that these impacts would have had benefits to life, especially early on ... these impacts might have actually allowed life to flourish," says Drabon.

The research was conducted in the Barberton Greenstone Belt, a geological formation located on the eastern edge of the Kaapvaal Craton in the Republic of South Africa. This area is considered to be the primordial crust of the Earth from 3.5 to 2.5 billion years ago. In addition to the S2 impact, evidence of at least eight other meteorite impacts has been discovered. Scientists intend to continue researching these issues.