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An island found off the coast of Brazil that was submerged 45 million years ago

Maria Tsikhotska

An island found off the coast of Brazil that was submerged 45 million years ago
45 million years ago, the island was flooded. Source: Wikipedia

In 2018, an international team of scientists conducted seabed research near a volcanic massif known as the Rio Grande Rise. During a dive to a depth of about 650 meters, they noticed unusual deposits of red clay that looked like tropical soil.

In the newest study, the researchers focused on studying the characteristic mineral composition of this clay, which could only have been formed by weathering in the open air under tropical conditions of heat and humidity. According to Live Science, this was the beginning of a series of discoveries.

The results of the research suggested that this part of the ocean, located 1200 km off the coast of Brazil, was once an island.

The researchers believe that the history of the Rio Grande Rise dates back to about 80 million years ago, when an intense volcanic eruption occurred under the mid-ocean ridge due to mantle plume activity, which formed this rise. Over time, as volcanism subsided, the plateau shifted westward across the Atlantic and gradually became submerged.

However, about 40 million years ago, there was a last outbreak of mantle plume volcanic activity isolated from the western part of the uplift. It was in this area that red clays sandwiched between lava flows were discovered. The analysis showed that their age is about 45 million years.

According to one of the authors of the study, marine geologist Luigi Jovane, these results are "outstanding" because the red clays are convincing evidence that the site was once an island.

The research began back in 2018 when scientists discovered a steep 30-kilometer-long canyon dividing the rise in half, as well as ancient terraces, sunken platforms, and waterfalls. Further dives and analyzes confirmed that a former tropical island, once visible on the ocean surface, is indeed hiding off the coast of Brazil. The red clays found are identical in composition to the "red earth" or "terra roxa" found throughout Brazil, which is strong proof of the scientists' conclusions.

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