Underwater team explores ocean floor

It is an environment that is strange, bizarre and altogether alien.

At the exotic locale of Pito Deep, a crew of researchers from Duke, the University of Hawaii and six other institutions studied the ocean floor near Easter Island and Tahiti from Jan. 30 to March 8. Penetrating the unexplored—to places that even light cannot—the crew led by Jeff Karson, a professor of geology at the Nicholas School for Environment and Earth Sciences, is beginning to unravel the earth’s geological history.

“Pito Deep is one of the few places on the seafloor where we can learn directly about the rocks in the subsurface,” Karson wrote in an e-mail from the Pito Deep Cruise in the South Pacific Ocean.

Almost 70 percent of the earth’s crust lies beneath the ocean, but it has not been studied as extensively as the continental crust. Karson and his team used submersible vehicles in canyons wider and deeper than the Grand Canyon that provide a glimpse of 3 million years of the earth’s history.

Nicholas Hayman, a research associate also from Duke, explained that the scientists set out to learn about the earth’s behavior, including its magnetic field, tectonic faults and magma flow.

“Complete understanding of our planet must obviously include a thorough understanding of both the oceans themselves as well as the crust at the bottom of the oceans and the life forms that exist within the oceans and live on the seafloor,” Emily Klein, an earth and ocean sciences professor at the Nicholas School, wrote in an e-mail.

Karson described the ride in Alvin—a three-person submarine that can dive up to 4,500 meters below sea level and is able to remain underwater for as long as 72 hours—as “a spaceship ride to another planet.” Rigged with mechanical arms, lights and cameras, Alvin collected samples and captured images of the seafloor.

“Ironically, it is very much like a desert in many respects with barren rock cliffs and mud-covered low-lying areas,” Karson wrote about the seafloor after viewing it first-hand from Alvin.

The ancient solidified lava fields are millions of years old and resemble “a strange blanket of clouds,” Hayman wrote. The terrain is interrupted by jagged canyons and frozen channels that once allowed magma to flow to the surface.

Juxtaposed with the barren landscape and dark cliffs of Pito Deep are white veins of quartz and other minerals that provide a prehistoric map of where hot fluids once passed through rocks, Karson explained. Hayman added that the team is gaining a better understanding of the “plumbing” of hydrothermal vents.

The crust of Pito Deep is an anomaly, formed with less heat and exhibiting fewer fractures than previously investigated areas. Karson hypothesized the rate at which the seafloor formed and the abundance of magma account for the differences.

Although the expedition is over, the data, images and samples brought back from the expedition still warrant further analysis, which the team will continue on land.


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