Continental crust formed 500 million years earlier than scientists thought

The first appearance and preservation of the continental crust on Earth during the Archean (4-2.5 billion years ago) has important

implications for plate tectonics, ocean chemistry andbiological evolution. This happened about half a billion years earlier than previously thought, according to a new study presented at the General Assembly of the European Geosciences Union (EGU) in 2021.

Today the oceanic crust is risingmid-ocean ridge where tectonic plates diverge. In turn, the continental crust is much older and was formed as a result of volcanism, when plates slammed into each other, raising a thicker and less dense layer of rock above sea level. It is contrasted with the oceanic crust, which is different in structure and composition.

The weathering process of the continental crustadded nutrients to the ocean. It was this process that may have played a role in maintaining primitive life. The question remains - when did the Earth's crust begin to form?

To try and answer this question, DesireeRoerdink of the University of Bergen in Norway and her colleagues analyzed 30 ancient rock samples from six locations in Australia, South Africa and India. They contain barite, which can form in hydrothermal vents - cracks in the ocean floor where warm, mineral-rich waters react with seawater.

“Barites don't really change, their chemical composition contains an imprint of the environment in which they were formed,” explains Roerdink.

She and her team used the ratiostrontium isotopes in sediments. The goal is to find out when the weathering crust began to enter the oceans. They found that weathering began about 3.7 billion years ago.

When the Earth formed 4.5 billion years ago, itthe landscape consisted of molten rock. Eventually, the outer layer of the planet cooled so much that it began to form a hard crust covered by the world's oceans.

This marked the beginning of a new geological aeonabout 4 billion years ago, known as archaea. It was then, according to scientists, that life first appeared. There is compelling evidence of microbial activity at least 3.5 billion years ago, but it is not known exactly when or how life began.

Aaron Satkoski of the University of Texas at Austin says the new study suggests life may have originated on land, not in the oceans.

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Weathering crust - continental geologicala formation formed on the earth's surface as a result of the weathering of rocks. The weathering crust is a loose surface layer of rocks formed as a result of weathering. As a rule, the weathering crust has a clay composition.

Mid-ocean ridge - a network of ridges,located in the central parts of all oceans. They rise above the abyssal plains by 2-3 km. The total length of the ridges is more than 70 thousand km. In these structures, the formation of new oceanic crust and the spreading process take place.

Tectonic plates are the constituent parts of the lithosphere responsible for the geological activity of our planet.

Continental crust or continental crust is the earth's crust of continents, which consists of sedimentary, granite and granulite-basalt layers. The average thickness is 35–45 km, the maximum is up to 75 km.