Scientists drill longest-ever piece of Earth's mantle from underwater mountain near 'Lost City'

Researchers have drilled the deepest-ever sample of rocks from Earth's mantle, penetrating 0.7 mile (1.2 kilometers) in the Mid-Atlantic Ridge, where the seafloor is spreading apart.

At this spot, which is rich in hydrothermal vents, the interactions between mantle rocks and seawater create chemicals that are important for life. Previous efforts to drill into mantle rocks brought to the surface in the deep sea had reached only 659 feet (201 meters) — not deep enough to look for organisms such as heat-loving bacteria that might dwell farther down, said Gordon Southam, a geomicrobiologist at the University of Queensland in Australia and a co-author of a new study describing the core sample.

"Every time the drillers recovered another section of deep core, the microbiology team collected samples to culture bacteria to determine the limits of life in this deep subsurface marine ecosystem," Southam wrote in an email to Live Science. "Our ultimate goal is to improve our understanding of the origins of life and to define the potential for life beyond Earth."

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The rock core can also answer questions about the movement of the mantle, said Johan Lissenberg, a geochemist at the University of Cardiff in the U.K. and first author of the study, published today (Aug. 8) in the journal Science. "We know from the rocks that erupt in oceanic volcanoes that the mantle has a lot of different 'flavors,'" Lissenberg told Live Science. These "flavors" are varying rock compositions that come from the recycling of tectonic plates into Earth's interior.

With the new mantle sample, "we can really try to see what flavors have we got and on what scale do they vary," Lissenberg said, "and then reconstruct how those different bits of the mantle melted and then how they migrated towards the surface."

So far, the team has found that rather than Traveling vertically, melts seem to move obliquely, Traveling in a diagonal, inclined path toward the surface, Lissenberg said.