Around 500 million years ago, the explosion of animal life in the oceans brought about significant changes to the planet. Surprisingly, the effects of this evolutionary burst extended deep into the Earth’s mantle, reaching thousands of kilometers below the surface.
Researchers from ETH Zurich in Switzerland, led by Andrea Giuliani, have discovered a link between the Cambrian explosion and a fundamental change within the Earth’s interior.
The Cambrian explosion refers to the rapid diversification of animal species that occurred approximately 541 million years ago. During this period, a wide range of animals, including arthropods and vertebrates, emerged.
To investigate the impact of this evolutionary phenomenon on the Earth’s mantle, the team analyzed rocks called kimberlites. Kimberlites are rock formations that originate from deep within the Earth and are brought to the surface through volcanic activity.
By studying the carbon isotopes in 144 kimberlite samples from around the world, the researchers observed a change in the levels of carbon-12, an isotope commonly associated with living organisms. They found that kimberlites younger than 250 million years old had higher levels of carbon-12.
The team theorizes that during the Cambrian explosion, a significant amount of organic matter was buried in sea-floor sediments. Over time, tectonic plate movements caused this organic matter to be carried deep into the Earth’s mantle through a process called subduction.
It takes millions of years for this material to travel back to the surface in the form of kimberlite rocks. Therefore, the researchers suggest that the only plausible source of the observed increase in carbon-12 levels is the organic carbon deposited during the Cambrian explosion.
Unique Insights
This study reveals a surprising connection between the evolution of animals during the Cambrian explosion and changes in the chemical composition of the Earth’s mantle. It shows the far-reaching impact that life on Earth can have, even deep within its interior. The ability to analyze kimberlite rocks provides a window into the Earth’s past, allowing scientists to uncover significant events and processes that shaped our planet.
