Meteorite impact shaped early Earth and promoted life

Meteorite impact shaped early Earth and promoted life
by Clarence Oxford
Los Angeles CA (SPX) Oct 22, 2024

Billions of years ago, Earth was a harsh environment, frequently bombarded by meteorites. One of the most significant impacts occurred 3.26 billion years ago, when a meteorite the size of four Mount Everests collided with the planet. This event, known as the "S2" impact, left geological evidence in the Barberton Greenstone Belt in South Africa and is the focus of new research that sheds light on Earth's early history.

Nadja Drabon, an early-Earth geologist and assistant professor at Harvard University's Department of Earth and Planetary Sciences, studies these ancient impacts. Her team's latest research, published in *Proceedings of the National Academy of Sciences*, offers a detailed account of the S2 meteorite impact and its profound effects on Earth's environment and early life.

"Picture yourself standing off the coast of Cape Cod, in a shelf of shallow water. It's a low-energy environment, without strong currents. Then all of a sudden, you have a giant tsunami, sweeping by and ripping up the sea floor," Drabon explained. The S2 meteorite, believed to be up to 200 times larger than the one that wiped out the dinosaurs, triggered a massive tsunami, mixing the ocean waters and carrying debris into coastal regions.

The heat generated by the impact boiled off the ocean's surface and heated the atmosphere, while dust from the collision blocked out sunlight, disrupting photosynthesis. However, life proved resilient. Drabon's analysis shows that bacterial populations, particularly iron-metabolizing bacteria, surged after the impact. The tsunami brought iron from the ocean depths into shallow waters, while the meteorite delivered phosphorus, essential for life, to Earth. This short-lived shift in microbial life reveals how catastrophic events can actually benefit early life forms.

"We think of impact events as being disastrous for life," said Drabon. "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."

Drabon and her team continue to explore the Barberton Greenstone Belt, where evidence of at least eight major meteorite impacts, including the S2, is preserved. Their work promises to uncover even more about how these cosmic collisions shaped the planet and life itself.

Research Report:Effect of a giant meteorite impact on Paleoarchean surface environments and life