Plate tectonics activated a connection between the chemical reactors on the Earth’s interior and on its surface, and that connection created the habitable planet that humans currently enjoy, ranging from oxygen in the atmosphere to climate-regulating carbon dioxide concentrations. But when and how plate tectonics was extracted remains a mystery, buried under a geological period of billions of years.
To look back at the planet’s distant past, the research team used zircon, one of the oldest minerals ever found on Earth. The group was led by Dustin Trail of the University of Rochester in New York, Jacob Butner of the Los Alamos National Laboratory in New Mexico and Michael Anderson, a geologist at the Smithsonian National Museum of Natural History in Washington, DC.
Zircons come from the Jack Hills in Australia, and the oldest specimens are about 4.3 billion years old, meaning that these almost indestructible minerals were formed when the Earth was about 200 million years old in its infancy. Together with other ancient zircons in Jack Hills that have the earliest history of the Earth until about 3 billion years ago, these minerals make scientists a very close approximation to the unbroken chemical chronology of the early planet.
“How we are transforming what we have today from the molten rock and metal ball of the earth,” Ackerson said. “None of the other planets have continents, or liquid oceans or life. In a sense, we are trying to answer the question of why the Earth is unique, to some extent we can answer with these zircons.”