Tuesday05 November 2024
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Beneath Easter Island's surface lies a geological anomaly: measurements from geologists do not align.

Researchers have made a discovery that challenges the theory of tectonic plate movement.
Под островом Пасхи в недрах Земли обнаружена аномалия: данные геологов не совпадают.

Volcanoes beneath Rapa Nui, or Easter Island, challenge the prevailing theory regarding the movement of tectonic plates beneath the Earth's surface, reports IFLScience.

The widely accepted theory suggests that tectonic plates rest on a layer of viscous rock resembling thick syrup, known as the mantle. This layer moves in unison with the plates, akin to a conveyor belt. Originating in 1912, this theory was proposed by Alfred Wegener. Although it was contentious at first, it gained acceptance in the latter half of the 20th century.

However, one of these contentious points may have been corroborated on Easter Island, located 3,600 km off the coast of Chile. The island itself was formed through volcanic eruptions millions of years ago.

It all began when a group of Cuban and Colombian geologists decided to date the eruption that ultimately created the island. The scientists sought zircon in the island's deposits, which allows for precise dating of when the magma solidified.

The team expected to find zircons that formed around 2.5 million years ago, when the earliest lava deposits on the island were believed to have formed. But the researchers were surprised to discover minerals that were approximately 165 million years old.

Chemical analysis of the zircon revealed that the ancient magma had the same composition as that erupted from the island's modern volcanoes. However, these volcanoes could not have been active 165 million years ago, as the plate beneath them is not that old.

It is likely that the ancient minerals originate from a volcanic source deep within the Earth's mantle, which was active even before the surface volcanoes formed.

Yet, this raises another issue. Scientists believe that Easter Island emerged due to a mantle plume, a gigantic column of molten rock. This allows material from the depths of the Earth's mantle to rise to the surface. For a long time, it was thought that these mantle plumes remained stationary while the Earth's plates moved over them, creating new volcanoes with each plate shift.

The research findings indicated that the mantle plume beneath Easter Island has been in place for about 165 million years. Therefore, the ancient zircon may be remnants of earlier magmas that were brought to the surface along with younger samples during a volcanic eruption.

The authors of the study note that the conveyor belt theory does not align with the notion that mantle plumes actually remain stationary for hundreds of millions of years.

Scientists suggest that the Earth's mantle is indeed moving, but at a significantly slower rate than the plates above it.

As a reminder, ancient ocean floor has been hidden in the Earth's mantle since the time of the dinosaurs. Geologists have discovered ancient oceanic crust buried deep within the planet and believe it could shed light on Earth's past.