Zapping a tiny zircon crystal from Australia tells researchers the Earth is 4.375 billion years old, oh, plus or minus 6 million years.
“We’ve proved that the chemical record inside these zircons is trustworthy,” said John Valley, lead study author and a geochemist at the University of Wisconsin, Madison. The findings were published recently (Feb. 23) in the journal Nature Geoscience article Hadean age for a post-magma-ocean zircon confirmed by atom-probe tomography
Confirmation of the zircon age holds enormous implications for models of early Earth. Trace elements in the oldest zircons from Australia’s Jack Hills range suggest they came from water-rich, granite-like rocks such as granodiorite or tonalite. That means Earth cooled down just 100 million years after the massive collision that formed the Earth-moon system.
“The zircons show us the earliest Earth was more like the Earth we know today,” Valley said. “It wasn’t an inhospitable place.”