Representative image of an ocean.
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Researchers have long argued that regions deep in the Earth’s oceans may harbor sites from which all terrestrial life sprung. In the Atlantic, they gave the name “Lost City” to a jagged landscape of eerie spires under which they proposed that the life-preceding chemistry may have churned.
And now for the first time, specialists have succeeded in getting a glimpse of this potential Garden of Eden.
A report in the journal Science on Thursday tells of a 30-person team drilling deep into a region of the mid-Atlantic seabed and pulling up nearly a mile of extremely rare rocky material. Never before has a sample so massive and from such a great depth come to light. The material is central to a major theory on the origin of life.
“We did it,” said Frieder Klein, an expedition team member at the Woods Hole Oceanographic Institution on Cape Cod in Massachusetts. “We now have a treasure trove of rocks that will let us systematically study the processes that people believe are relevant to the emergence of life on the planet.”
The drilled region sits alongside one of the volcanic rifts that crisscross the global seabed like the seams of a baseball. Known as mid-ocean ridges, the abyssal sites feature hot springs whose shimmering waters shed minerals into the icy seawater, slowly building up strange mounds and spires that sometimes host riots of bizarre creatures.
For decades, scientists have theorised that the hot springs or their underlying rocks nurtured geochemical reactions that billions of years ago begot terrestrial life. Recently, they’ve accelerated their hunt for supporting clues.
“A lot of people did lab work and paper studies and modeling on the origin of life,” said Deborah Kelley, an oceanographer at the University of Washington who has scrutinised such clues but is independent of the team. The new research, she said, “is really important.”
She added, “It lays a foundation for new understanding.”
Early last year, the expedition, formally titled Building Blocks of Life, drilled deep into the rocky seabed adjacent to one of the largest known springs — a mid-Atlantic site some 1,400 miles east of Bermuda known as Lost City, which Kelley helped uncover in 2000. Its tallest spire rivals a 20-story building.
The core retrieved nearby has a length of 1,268 meters, or some four-fifths of a mile, far deeper and more substantial than any comparable sample from beneath the undersea springs.
The operation has brought into scientists’ labs the first long section of rocks originating in the mantle — the inner layers between Earth’s crust on which we live and the planetary core. It is the largest region of the planet, but its inaccessibility makes it poorly understood. Over eons, hot mantle rocks flow like extraordinarily thick fluids that slowly rearrange the cool planetary crust, lifting mountains, moving continents and causing earthquakes.
Scientists expect years of scientific discovery to emerge from detailed analyses of the rocky bonanza, including how it bears on the origin-of-life question.
“It’s too early to say anything really specific because the results are not yet in,” said C Johan Lissenberg, the first author of the Science paper and a petrologist at Cardiff University in Wales. “But we’ll find out. That’s the excitement.”
The mantle breakthrough was part of the International Ocean Discovery Program, a research consortium of more than 20 countries using a giant ship to drill into the ocean floor and retrieve rocky samples that bare Earth’s secrets. The ship is a modified oil exploration platform, 470 feet long and with a 200-foot derrick that lowers a hollow drill that bores into the seabed and retrieves cylindrical samples of rocks and other deep materials.
“We were astounded” at how easily the rocky samples came to light, Lissenberg said. “They tend to fracture quite easily, and that jams the drill. We were like kids in a candy store seeing core after core coming up.”
Lost City, like all deep springs, formed when water moving beneath the seabed gained enough heat to rise buoyantly and mix with icy seawater, prompting the precipitation of minerals that created its spires and towers.
Its discovery, however, marked the scientific debut of a new class of deep spring very different from those previously studied, in which rock chimneys spew extraordinarily hot water black with minerals, nicknamed black smokers. In contrast, Lost City was located not atop the mid-Atlantic rift but off to one side, its fluids cooler and spires taller.
The discovery raised waves of excitement in the community that studies life precursors because Michael J Russell, a geochemist at NASA’s Jet Propulsion Laboratory in California, had predicted the existence of such cooler springs. He saw them as ideal for nurturing life.
That history explains the current excitement to see what analyses of the expedition’s rocky samples bring to light. Klein said the findings could bear on the origin of life not only on Earth but also elsewhere in the solar system and the universe.
“The importance of this ship and the cores cannot be overestimated,” he said. “This is a basic resource for the future.”