A recent research has provided strong evidence that the Earth’s continents were formed by giant meteorite impacts. On August 10, 2022, a team of scientists led by Dr Tim Johnson from Curtin University’s School of Earth and Planetary Sciences published its study in the peer-reviewed journal Nature. The paper is titled Giant Impacts and the Origin and Evolution of Continents.
Understanding the formation and ongoing evolution of the Earth’s continents was crucial, as these landmasses host the majority of the Earth’s biomass, all humans, and nearly all of the planet’s important mineral deposits. The researchers are going to further test their findings on other areas of ancient continental crust on the Earth to further validate their research model.
The Study
The theory that the continents were formed at the sites of massive meteorite impacts has been there for so many years. However, only now, there is concrete evidence to support the theory. The Earth is the only planet known to have continents. For understanding how the continents came into being, the research team examined the tiny crystals of the mineral ‘zircon’ in rocks from the Pilbara Craton in Western Australia. Pilbara Craton represents Earth’s best-preserved remnant of ancient crust.
The scientists found evidence of the impact of giant meteorite by studying the composition of oxygen isotopes in the zircon crystals. The investigation revealed a ‘top-down’ process, which started with the melting of rocks near the surface and progressed deeper consistently with the geological effect of giant meteorite impacts.
The study of zircon crystals indicated that the heat that melted and transformed the rock did not come from the below, but from the above. According to the researchers, the processes that ultimately formed the continents began with a giant meteorite impact. It was similar to those that were responsible for the extinction of dinosaurs billions of years ago. The researchers also found elements that could support the present green technologies as lithium, tin, and nickel found in the continents are essential commodities to the emerging green technologies which help in mitigating climate change.
Pilbara Craton
Pilbara region in Western Australia is the region known for its ancient landscapes. Pilbara Craton is an old and stable part of the Earth’s crust and is home to evidence the earliest known life on land. It is one among the very few places in the world where scientists have identified crustal rocks which are between 3.6 to 2.7 billion years old. Pilbara Craton is called the Archean eon by scientists. Archean eon is the second of the four geologic eons the other three being Phanerozoic, Proterozoic, and Hadean in the Earth’s history, representing the time from 4 billion to 2.5 billion years ago. During this period, the Earth’s crust had cooled enough for continents to form, and for the earliest known life to start.
© Spectrum Books Pvt Ltd.