The origin of Bermuda was explained by an unusual, previously unknown mechanism of volcanic activity.
A large international group of geologists with the participation of Aleksandr Sobolev, an employee of the GEOKHI RAS, published an article in the journal Nature, which shows that Bermuda was formed due to the activity of extremely unusual volcanoes. Scientists have not considered such a mechanism of volcanism before, but it may be associated with the formation of some other volcanic archipelagos in the World Ocean.
As a rule, volcanoes form in places where tectonic plates diverge (as in mid-ocean ridges), or where one plate sinks under another (in subduction zones, like off the coast of Japan), or under the influence of persistent vertical magma flows that rise from the depths of the mantle and gradually "melt" the lithospheric plate above it (as in Hawaii). For many years it was believed that the ancient, long extinct volcanoes, which once raised the Bermuda Islands from the bottom of the Sargasso Sea, acted under the influence of mantle plumes.
Indeed, a stable plume is recorded in this area. On the other hand, such a plume should leave a characteristic chain of islands, as in Hawaii, due to the slow movement of the crust over a stationary vertical magma flow. In addition, no volcanic activity has been observed in the area that this current is supposed to affect today. To understand these inconsistencies, geologists conducted additional analysis of an 800-meter core obtained in Bermuda back in 1972. The unusual mineral composition, as well as the content of isotopes of lead and some other heavy elements, allowed scientists to put forward a new scheme for the formation of this archipelago.
Disturbances in magma currents caused the rise and mixing of the matter of fragments of ancient plates preserved in the transition zone of the mantle / Sarah Mazza et al., 2019.
It is worth remembering here that the entire Atlantic Ocean appeared about 175 million years ago, as a result of the split of the Pangea supercontinent, which previously united almost all of the earth's land. The plates that make up Africa, Europe and the Americas today parted, and an ocean appeared between them. Numerous fragments of plates plunged into the mantle under its bottom, sinking into its transition zone at a depth of about 400-600 kilometers. About 30 million years ago, disturbances in mantle flows caused several of these semi-molten debris to float higher, interacting with water, merging and mixing. Such a process could have created not only Bermuda with their unusual geology, but also some other volcanic islands in the oceans of the Earth.
Sergey Vasiliev