Curtin’s new research has found evidence that Earth’s first continents were the result of being hit by comets as our Solar System moved in and out of the spiral arms of the Milky Way, overturning traditional thinking about the formation of our planet
The new research, published in Geology, challenges the existing theory that the Earth’s crust was formed solely by processes within our planet, shedding new light on Earth’s formative history and our place in the cosmos.
Lead researcher Professor Chris Kirkland, from the Mineral Systems Scales Group in Curtin’s School of Earth and Planetary Sciences, said the study of minerals in the Earth’s crust revealed a rate of production of crust every 200 million years or so that matched the transit of our Solar System through areas of the galaxy with higher star density.
“The Solar System orbits the Milky Way, passing between the galaxy’s spiral arms approximately every 200 million years,” Professor Kirkland said.
“Looking at the age and isotopic signature of minerals from both the Pilbara Craton in western Australia and the North Atlantic Craton in Greenland, we see a similar rate of crustal production, which coincides with periods during the which the solar system traveled through areas of the galaxy most populated by stars.”
“When passing through regions of higher stellar density, comets would have been dislodged from the far reaches of the Solar System, some of which impacted Earth.
“The increased impact of the comet on Earth would have led to further melting of the Earth’s surface to produce the floating cores of the first continents.”
Professor Kirkland said the findings challenged the existing theory that the production of crust was entirely related to internal processes on Earth.
“Our study reveals an exciting link between geological processes on Earth and the motion of the Solar System in our galaxy,” said Professor Kirkland.
“Linking the formation of the continents, the land masses where we all live and where we find most of our mineral resources, with the passage of the Solar System through the Milky Way sheds a whole new light on the formative history of our planet and its place in the cosmos”.
Professor Kirkland is affiliated with The Institute for Geoscience Research (TIGeR), Curtin’s flagship Earth Sciences research institute.
Researchers from the University of Lincoln, the Astromaterials Research and Exploration Science Division at NASA’s Johnson Space Center and the Geological Survey of Western Australia also contributed to the study.
The full research paper, “Did seed crust production on the early Earth transit through the galactic spiral arms?” was published in the journal Geology and can be found online here.