After more than two months on board ice-breaking ships, scientists have finally mapped and sampled the Gakkel Ridge, a never-before-studied part of the mid-ocean ridge system. Announcing their preliminary results yesterday, the researchers described unexpected pockets of volcanic activity and fields of hydrothermal vents on the seafloor near the North Pole.
The Gakkel Ridge extends 1,100 miles from north of Greenland to Siberia and is the deepest and most remote mid-ocean ridge. Indeed, it lies in its entirety beneath the Arctic ice cap. Studying the ridge thus requires ships capable of breaking huge amounts of ice.
New ocean crust is created at mid-ocean ridges as the seafloor spreads apart and melted magma from the earth's mantle reaches the surface. The Gakkel Ridge is one of the slowest spreading mid-ocean ridges and, as such, was not expected to contain many of the deep-sea hot springs that host abundant life on the seafloor. According to Charles Langmuir of Columbia University, however, the expedition "found more hydrothermal activity on this cruise than in 20 years of exploration on the mid-Atlantic ridge."
The scientists also recorded an unexpected amount of volcanic activity along the ridge. Because the southern end of the ridge spreads more quickly than the northern end, the researchers expected to see less volcanic activity as they traveled north. Instead they found irregular pockets of volcanic activity. "Our maps show that this ridge is tectonically different than other ridges, the rift valley is close to a mile deeper with many enormous long-lived faults," Henry Dick of the Woods Hole Oceanographic Institution notes.
As a result of this expedition, the researchers now have the most detailed map ever created of the least accessible mid-ocean ridge. "These exciting discoveries on Gakkel Ridge," team member Peter Michael of the University of Tulsa says, "pave the way for future expeditions that will map the vents and may discover completely new organisms."