The stern of the research vessel, the R/V Knorr while at sea in 2004 (IMAGE)
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The stern of the research vessel, the R/V Knorr while at sea in 2004. The A-frame structure holds the giant metal and chain bucket which is lowered more than 10,000 feet below the ocean surface and dragged along the seafloor to collect geologic samples.
The research team sought to understand the relationship between Earth’s solid mantle and modern seafloor volcanic rocks. The researchers started by studying a group of rocks that were dredged from the seafloor at two oceanic ridges where tectonic plates are spreading apart and the mantle is churning up to the surface and producing new crust. The two places the studied rocks were collected from, the Gakkel Ridge near the North Pole and the Southwest Indian Ridge between Africa and Antarctica, are two of the slowest-spreading tectonic plate boundaries in the world.
A new analysis of rocks thought to be at least 2.5 billion years old by researchers at the Smithsonian’s National Museum of Natural History helps clarify the chemical history of Earth’s mantle—the geologic layer beneath the planet’s crust. The study, published today in the journal Nature, centered on a group of rocks collected from the seafloor that possessed unusual geochemical properties.
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Emily Van Ark
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