Ancient Australian zircon reveals clues to Earth’s formation
DOI: 10.1063/PT.5.027712
BBC : The oldest piece of Earth’s crust—a zircon crystal—has been found in the Jack Hills region of Western Australia. At least 4.4 billion years old, the zircon is being studied by John Valley of the University of Wisconsin–Madison and colleagues, whose paper appears in Nature Geoscience. The researchers determined the crystal’s age by looking at the ratio of uranium atoms to those of lead, its decay product. Due to its hardness and durability, zircon can survive many geologic processes; that ability makes it one of the oldest materials on Earth. By looking at oxygen isotope ratios and other properties of the zircon, the researchers have determined that Earth’s crust is older than previously believed and that its surface became habitable very early on in the planet’s existence.
