Opening details

Earth’s first continents may have emerged from primordial oceans much earlier than we think, just six hundred million years after the planet was formed. Researchers discover ancient zircon crystals in the Jack Hills Hills of Western Australia Contains freshwater signatures indicating the presence of land areasBecause fresh water can only form if there is soil where it can accumulate after rainfall.

The composition of the early Earth has long puzzled scientists. When our planet first formed 4.6 billion years ago, it was a sphere of violent magma. The next epoch, called the Hadean (4.6-4 billion years ago), is little researched. While we understand logically that this magma eventually solidifies and forms the crust, we don’t know exactly what happens next.

some scientists Suggests Earth may have been mostly covered with water some 4.4 billion years agoThis corresponds to the age of the oldest zircons ever found. However, it is not clear exactly how water appeared. Perhaps it was part of the planet’s initial composition, perhaps it was the result of bombardment by icy asteroids.

clean water could have arisen only if the hydrological cycle had already begun during the existence of the Earth – evaporation and precipitation, and the ability of water devoid of minerals found in salt water to accumulate in new areas of the continental crust.

Scientists found that zircons extracted from Jack Hills rocks contained higher levels of light oxygen isotopes than zircons formed in the presence of seawater; This suggests that it forms when magma rises to the surface and interacts with fresh water.

Zircons provide the answer

Scientists determined the age of the crystals by measuring the ratio of different uranium isotopes in the samples. Many of the 1,400 zircons analyzed were dated 3.4 billion years so and a few more – 4 billion years before. Most were much younger, with the newest crystals dating back 1.85 billion years.

Zircons are extremely durable. As a result, they become trapped in rocks that are much younger than themselves, and young and old zircons are mixed together. According to the presentation, the rock where the Jack Hills zircons are found is 3 billion years old.

Because of their stability, zircons are extremely useful for understanding exactly when the continental plates formed by the Earth’s crust began to break the surface of the world’s oceans. The oldest rock ever found dates back 4.03 billion years, but the oldest zircons are hundreds of millions of years older than that, providing a rare insight into the planet’s early history.

If the researchers are right, uninhabited land islands may have emerged from primitive waves earlier than we thought.