The truth from the 4.2 billion year old "treasure"

In a study recently published in the journal PNAS , scientists studied nearly 1,000 zircons collected from the Jack Hills region of Australia, which holds important geological evidence of the Earth's "infancy."

The results showed that more than 35% of these zircons belonged to the S type, a crystal group that represents plate tectonic activity.

Plate tectonics is the process by which tectonic plates - which can be roughly understood as pieces of the Earth's crust - shift, slide over each other, rise from the mantle or sink.

Although it causes terrible events - from the merging and splitting of continents to earthquakes, volcanoes... - plate tectonics also plays an important role in stabilizing the climate, atmosphere, and maintaining the chemical balance of the planet.

Therefore, plate tectonics is one of the necessary conditions for the Earth to generate and preserve life.

Previously, it was thought that this process only began after or at the end of the Hadean eon, the "fireball" phase of Earth, which lasted from Earth's conception until 3.8 billion years ago.

However, among the newly identified S-type zircons in Australia, there is a date of 4.2 billion years ago.

It is evidence of the beginning of tectonic activity.

During the Hadean eon, Earth possessed a watery atmosphere of ammonia and methane, which eventually condensed into an ocean that covered the entire planet. During this period, Earth gradually cooled to form a solid outer shell.

The 4.2-billion-year-old zircon "treasures" show that at that time, the outer crust had not only formed but had also separated into tectonic plates, initiating a shift that was extremely important for the planet's evolution.

This shows that our planet went through a much more dynamic and rapidly evolving early period than previously thought.

The work was led by a team of authors from the Institute of Geology and Geophysics and the University of Earth and Planetary Sciences, both of the Chinese Academy of Sciences.