Approximately 3.26 billion years ago, our planet was struck by a colossal space rock. The event has compelled scientists for centuries – and even today, it's helping them unlock secrets from Earth's distant past.
One such scientist is Nadja Drabon from Harvard University, and she is determined to find answers about this chaotic chapter of Earth's history. When did the first oceans emerge? When did continents start to form? And how did these meteor impacts shape the evolution of life on Earth?
It's no small feat – determining the answers to these profound questions – but in a recent study in Proceedings of the National Academy of Sciences, Drabon has given it a go.
Drabon's study focuses on the 'S2' meteorite impact that occurred over 3 billion years ago. Evidence of this event is found in the Barberton Greenstone Belt of South Africa. By meticulously analysing rock samples and studying their sedimentology, geochemistry and carbon isotope compositions, Drabon and her team have pieced together a vivid picture of what happened when this giant meteorite – larger than four Mount Everests – collided with Earth.
"Picture yourself standing off the coast of Cape Cod in a shelf of shallow water," says Drabon. "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."
The S2 meteorite, estimated to be 200 times larger than the asteroid that wiped out the dinosaurs, triggered a tsunami that disrupted the oceans and swept debris from land into coastal waters.
The intense heat from the impact boiled off parts of the ocean’s surface, heated the atmosphere, and cast a thick cloud of dust over the planet, halting photosynthesis. Yet life found a way to persist.
Drabon’s analysis reveals that bacteria rebounded quickly after the impact. Populations of iron- and phosphorus-loving microorganisms surged, as the tsunami stirred up iron from the ocean depths, and the meteorite delivered phosphorus to the environment. This temporary shift towards iron-metabolising bacteria offers a rare glimpse into how life adapted and thrived in the wake of catastrophe.
While meteor impacts are often seen as destructive, Drabon’s study suggests they may have played a crucial role in nurturing early life.
"We think of impact events as being disastrous for life," says 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’s ongoing work in South Africa’s Barberton Greenstone Belt, where at least eight major meteor impacts have been identified, continues to provide new insights into how these ancient cataclysms shaped our world.
Her team plans to delve even deeper into Earth’s history, exploring how meteorites may have played a role in the planet’s evolution.
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