Introduction
Over 500 million years ago, the explosive evolution of animal life in the oceans had a profound impact on our planet. Recent research suggests that this burst of evolution also caused significant changes in the chemical composition of Earth’s mantle.
Linking Earth’s Surface Events with the Deep Earth
Andrea Giuliani from ETH Zurich in Switzerland highlights the connection between a major event on Earth’s surface and a fundamental change deep within the planet. By studying rocks called kimberlites, which originate from the depths of the Earth, researchers can uncover the pristine signals of these changes.
The Cambrian Explosion
The “Cambrian explosion” marked the emergence of a wide range of animal groups approximately 541 million years ago. This period witnessed the evolution of familiar animal groups, including arthropods and vertebrates.
Studying Kimberlites to Unearth Clues
Giving insight into the deep Earth, researchers analyzed 144 kimberlites and related rocks from various locations worldwide. Kimberlites offer a unique perspective as they contain a pristine signal of the Earth’s composition. By examining the different isotopes of carbon found in these rocks, the team made significant findings.
The Rise of Carbon-12
The research team led by Giuliani discovered that kimberlites younger than 250 million years showed an increase in carbon-12 levels. This rise is attributed to large amounts of organic matter being buried in sea-floor sediments during the Cambrian explosion.
Transportation into Earth’s Mantle
Tectonic plate movement leads to the subduction of organic-rich material into Earth’s mantle. It takes an extended period for this material to reach the surface in rocks like kimberlite, with a minimum estimated time of 250 million years. The Cambrian explosion is believed to be the primary source of this organic carbon.
Conclusion
The evolutionary burst of animal life during the Cambrian explosion had far-reaching consequences, extending beyond Earth’s surface and into the deep Earth. Understanding these changes in the mantle’s chemical composition provides valuable insights into Earth’s history and the impact of biological events on our planet’s geological processes.
