New evidence that a giant asteroid impact created the continents

New research has revealed the strongest evidence yet that Earth’s continents formed as a result of a giant meteorite impact, which was especially common during the first billion years or so of our planet’s four and a half billion year history. Curtin University researchers conducted the study, which was published on August 10, 2022 in the journal temper nature.

According to Dr. Tim Johnson, of the Curtin School of Earth and Planetary SciencesAnd the The idea that continents originally formed at giant meteorite impact sites has been around for decades. However, there has so far been little solid evidence to support this theory.

“By examining small crystals of the mineral zircon in rocks from the Pilbara Craton in Western Australia, which are the best preserved ancient crustal remnants on Earth, we have found evidence of these giant meteorite impacts,” said Dr. Johnson.

Studying the oxygen isotope composition in these zircon crystals revealed a ‘top-down’ process that begins with melting of rocks near the surface and progresses deeper, consistent with the geological impact of giant meteorite impacts.

“Our research provides the first strong evidence that the processes that eventually formed the continents began with giant meteorite impacts, similar to those responsible for the extinction of the dinosaurs, but occurred billions of years ago.”

Understanding the formation and continued evolution of Earth’s continents is critical according to Dr. Johnson because these land masses host the majority of Earth’s biomass, all humans, and nearly all of the planet’s important mineral deposits.

“Not least that the continents host important minerals such as lithium, tin and nickel, which are essential commodities for the emerging green technologies needed to fulfill our commitment to mitigating climate change,” said Dr. Johnson.

“These mineral deposits are the end result of a process known as crustal differentiation, which began with the formation of the early land masses, of which the Pilbara Craton is only one.

Data for other areas of the ancient continental crust on Earth appear to show patterns similar to those recognized in Western Australia. We’d like to test our findings on these ancient rocks to see if our model is applicable to a larger scale, we suspect. “

Reference: “Giant impacts and the origin and evolution of the continents” by Tim E. Johnson, Christopher L. Kirkland, Young John Law, R. Hugh Smithies, Michael Brown, and Michael Hartnady, August 10, 2022, temper nature.
DOI: 10.1038 / s41586-022-04956-y

Dr. Johnson is affiliated with the Institute for Earth Science Research (TIGeR), Curtin’s leading Earth science research institute.