A massive ancient island, now submerged under the Atlantic Ocean, could be a treasure trove of rare earth elements and precious minerals. This island, known as the Rio Grande Rise (RGR), emerged as a volcanic ridge about 40 million years ago and was once a lush tropical landmass.
Situated roughly 1,200 kilometers off Brazil’s coast, the RGR spans an impressive 150,000 square kilometers of the ocean floor. Depths here vary from 700 to 2,000 meters. The theory that this ridge might have been an island surfaced in 2018 and has since been confirmed through recent soil analysis from the western RGR.
The study found that the sediment primarily consists of red clay, similar to the “red earth” found in São Paulo state. This soil contains minerals typical of volcanic rock alterations, such as oxidized magnetite, hematite, goethite, and kaolinite.
These discoveries suggest that the clay formed due to intense chemical weathering of volcanic rocks in a warm, wet climate with active volcanoes. The researchers believe the RGR was exposed to these conditions during the Eocene epoch, around 35 million years ago, a time known for its tropical climate.
“Our research and analysis confirmed it was indeed an island,” said study author Luigi Jovane. He noted that the clay formation occurred after the last volcanic activity, dating it between 30 million and 40 million years ago, under tropical conditions.
Previous studies have also shown that this submerged island is rich in valuable minerals like cobalt, lithium, and nickel, along with sought-after rare earth elements such as tellurium. These materials are crucial for new technologies that are steering us away from fossil fuels, sparking significant interest in mining the RGR’s resources.
The ridge, located in international waters, falls under the jurisdiction of the International Seabed Authority. However, Brazil has sought to extend its continental shelf to include the RGR, a move unlikely to be approved due to the UN Convention on the Law of the Sea’s regulations.
“To understand if resource extraction from the seafloor is feasible, we must consider the sustainability and impacts of such activities,” Jovane emphasized. He highlighted the importance of understanding how extraction would affect marine life and the overall environmental impact.
This study has been published in the journal Scientific Reports, shedding light on the potential and challenges of harnessing the natural riches of the Rio Grande Rise.