Scientists have shown that the volume of rock remains and dead animals regulates the speed at which tectonic plates collide.
Researchers from the Texas Institute of Geophysics, using the example of the created model, suggested that the speed of movement of the continents depends on sediments (solid particles carried by water currents). Their hypothesis explained the early collisions of the continents. The work was published in the journal Earth and Planetary Science Letters.
Sediments, or sediments, are fragments of rock resulting from erosion, or particles of dead organisms such as shells and skeletons that accumulate in one place. Based on data on seismic activity and a semiempirical formula for the velocities of the Konrad and Hager plates, the authors created their own model that explained the role of sediments in the long-term movement of continents.
Previously, it was assumed that the rate of subduction - the process of submersion of one plate under another - depends on the strength of the plates themselves. However, this hypothesis did not explain the changes in its speed. Most often, its zone is located on the border of oceanic and continental plates. In this case, the oceanic goes under the continental and plunges into the mantle. Scientists at the Texas Institute of Geophysics theorized that sediments can promote subsidence and serve as slip-inducing material. Their model confirmed this assumption.
According to her, the whole process has the opposite effect. At a higher speed of movement, a sufficient volume of sediment necessary to maintain the speed does not have time to form on the surface of the plates, and deceleration begins. With a delay, the material accumulates - and the whole cycle repeats.
India's movement and speed / © Earth and Planetary Science Letters
As one of the examples, the authors cited the collision of India with the Asian continent 50 million years ago. According to them, while India was moving along the equatorial seas, it collected sedimentary rocks, after which its speed increased from five centimeters per year to 16, but before the collision with Asia, the volume of sediment decreased - and the continent slowed down.
In September, geologists at the University of Plymouth in England concluded that Armorica, part of the continent in the northwest of modern France, also played a role in the formation of the British Isles. Most likely, a piece of Armorica broke away from the main continent and eventually joined the British Isles.