SYDNEY, Sept. 16 (Xinhua) — Australian scientists have uncovered a striking link between the structure of our galaxy and the evolution of Earth’s crust.
The study shows Earth’s crust development was shaped by the impact of meteorites during its journey through the Milky Way and not solely through internal processes as was previously widely considered, according to a statement released Tuesday by Australia’s Curtin University.
The study reveals that the chemistry of tiny ancient crystals in Earth’s crust may capture the rhythm of meteorite impacts during the solar system’s passage through the Milky Way’s vast spiral arms.
The work provides new evidence linking Earth’s ancient geological record with the large-scale structure of the Milky Way, said Professor Chris Kirkland from Curtin University, the lead researcher of the study published in Physical Review Research.
“Tiny, durable minerals called zircon crystals provided a unique archive of Earth’s interaction with the galaxy,” Kirkland said.
By examining chemical changes in zircon crystals and comparing them with maps of gas in the Milky Way, researchers observed that the changes corresponded with times when the Solar System passed through the galaxy’s spiral arms, which are densely packed with stars and gas.
“In these crowded regions, extra gravitational forces may have disturbed icy comets at the edge of our Solar System, knocking some onto paths that sent them crashing into Earth,” Kirkland said, adding the impacts released great energy that melted parts of Earth’s surface and generated more complex magmas, particularly in water-rich areas.
“It suggests that astrophysical processes on the scale of the Milky Way may have directly influenced the continents beneath our feet and the conditions that made life possible, ushering in a new era of astro-geological science,” he said. ■