A team of Chinese researchers from the Ocean University of China have recently published a reconstruction of the movements of lithospheric plates relating to the last 1.8 billion yearsusing information from rocks around the planet. Evolution was represented in the form of a video that traces approximately the 40% of Earth’s historywhich is 4.54 billion years old. Knowing the movements of tectonic plates in the past is fundamental because these have influenced the evolution of climate and life on our planet.
There lithospherethe Earth’s outermost layer which includes the crust and the upper solid portion of the mantle, is divided into blocks called lithospheric plates. Over time, these move away and towards each other, sliding on the underlying asthenosphere (the plastic layer of the mantle, made up of partially molten rocks), pushed by convective movements involving mantle materials. The lithospheric plates are made up of both the ocean floor and the continents, which they drag along with them in their movements. The animation initially shows the current arrangement of the continents.
Going backwards in time, South America and Africa gradually move closer together until they join, as do North America and Europe, while India moves south, followed by Southeast Asia and Oceania joins Antarctica. Approximately 200 million years ago the continents are joined together to form the supercontinent Pangea. Pangea then progressively disintegrated and the continents migrated until they formed, about 450 million years ago, a large continent called Gondwana in the Southern Hemisphere and three other smaller continents in the Northern Hemisphere (Laurentia, Baltic And Siberia). The continents move away from each other and come closer together again until approximately 1.3 billion years ago another supercontinent is formed, called Rodinia. The reconstruction proceeds until 1.8 billion years agowhen there was another supercontinent: Nuna.
The movements of the lithospheric plates, although extremely slow, can have tangible consequences on our lives, since they cause earthquakes and volcanic eruptions. Plate tectonics, however, plays an even more important role, because it has allowed the life on earth as we know it. For example, with the formation of mountain ranges they are brought to the surface chemical elements previously buried, which exogenous agents erode and transport to the oceans, where they become available to living beings. These include, for example, phosphorus, which constitutes the molecules of DNA, and molybdenum, used by organisms to produce proteins and amino acids. The interaction between precipitation water and the rocks of the emerged lands It then removes large quantities of carbon dioxide from the atmospherewhich reaches the oceans, regulating the temperature of our planet. Thanks to the movements of the plates, gases are released on the ocean floor that microorganisms feed on: it is believed that these emissions have made the origin of life possibleof which the first evidence dates back to 3.5 billion years ago.
What is the point of reconstructing the evolution of continents?
Reconstructing the movements of the lithospheric plates in the past helps us better understand the mechanisms underlying the climatic variations that have occurred over time. Furthermore, it is essential to understand when and how chemical elements began to fuel life and when the atmosphere was enriched with oxygen. Many metals essential to man are also found along the edges of the plates: knowing the ancient distribution of the plates is useful for identifying new deposits.
