Plate tectonics enabled the link between a chemical reactor in Earth’s interior and its surface, and this connection created the habitable planet that humans currently enjoy, from oxygen in the atmosphere to climate-regulated CO2 concentrations. But when and how plate tectonics were fired remains a mystery, buried under billions of years of geological time.
The research team used zircon, the oldest mineral found on Earth, to peek into the planet’s distant past. The team included Dustin Trail of the University of Rochester in New York, and Jacob Buettner of Los Alamos National Laboratory in New Mexico, and was led by geologist Michael Anderson of the Smithsonian National Museum of Natural History in Washington, DC.
Zircon came from Jack Hills in Australia and the oldest samples were about 4.3 billion years old, which means that these nearly indestructible minerals were formed when Earth itself was in its infancy and were only about 200 million years old. Along with other ancient zircons from Jack Hills that extend back to the oldest history of Earth up to about 3 billion years ago, these minerals form the closest approximation that scientists have of the unbroken chemical history of the first planet.
“We’re rebuilding how the Earth changed from a molten ball of rocks and minerals to what we have today,” said Akerson. “None of the other planets have continents, liquid oceans, or life. In a sense, we are trying to answer the question of why Earth is so unique, and to some extent we can answer it with these zircons.”