Later, new continents appeared when plate tectonics pushed huge rocks out of the sea.
Scientists have found evidence of an ancient water world, which is stored in ancient seabeds in today’s arid outback lands in northwestern Australia.
About 4.5 billion years ago, high-speed collisions of space rock and dust formed the beginning of our planet, a sphere of molten and bubbling magma rock deep into the heart. tens of thousands of kilometers. The sphere then cooled as it rotated, and eventually after about 1,000 to 1 million years, the cooled magma formed the first mineral crystals in the Earth’s crust.
Water on Earth may have come from icy comets.
Meanwhile, the first drops of water may have been brought to Earth by icy comets. These comets come from outside our solar system. It is also possible that water reached Earth in dust particles from the clouds that gave birth to the Sun and other planets orbiting the Sun, around the same time the Earth formed.
Associate Professor Benjamin Johnson of the Department of Geosciences and Atmosphers, Iowa State University, USA, said that when the Earth was still an ocean of molten magma, water evaporated and gases rose into the atmosphere. . Then there is rain from the atmosphere when the ground cools enough. From this study, we don’t know for sure where the water came from but it could be from any source, water was present when our planet was still just a magma ocean.
In this new study, Professor Johnson and co-author, Boswell Wing, an associate professor of geosciences at the University of Colorado Boulder, USA, focused on the barren remote lands of Australia. The rock here holds a hydrothermal system from 3.2 million years ago and the features of the entire crust are oceanic from the surface to the bottom with thermal energy creating cycles.
Hidden in the jagged seafloor are isotopes of oxygen. Over time, the relationships between these isotopes have helped scientists decipher changes in ancient ocean temperatures and global climate.
This spherical basalt rock lay on the seabed about 3.2 billion years ago.
However, the scientists also made a surprising discovery when they analyzed more than a hundred sediment samples. That was 3.2 billion years ago, the vast ocean contained more oxygen-18 than oxygen-16 (while today’s oceans contain more oxygen-16). Computer models show that at the global level it is different from the continental mass that takes oxygen-18 out of the oceans. Without the continents, the oceans would be richer in oxygen-18. And the ratio between these two oxygen isotopes shows that at that time there were no continents.
Previously, researchers believed that the Earth was once covered with water. However, they disagree on the amount of land that rises above the ocean’s surface. The recent discovery revealed the actual geochemical conditions of having land emerge above sea level.
The hypothesis of an ancient water-filled Earth also raises the possibility of a new question, which is where on the planet the first life forms appeared and how they evolved.
Professor Johnson said: “ There are two great cradles of the origin of life: vents and hydrothermal lakes on land. If our research results are correct, the number of terrestrial environments in which life can reproduce and evolve is extremely small or even nonexistent until 3.2 billion years ago. year”.
The study was just published March 2 in the American Journal of Natural Geosciences.