Scientists recently concluded an expedition aboard the research vessel JOIDES Resolution to learn more about Atlantis Massif, an undersea mountain, or seamount, that formed in a very different way than the majority of the seafloor in the oceans.
Unlike volcanic seamounts, which are made of the basalt that's typical of most of the seafloor, Atlantis Massif includes rock types that are usually only found much deeper in the ocean crust, such as gabbro and peridotite.
The expedition, known as Integrated Ocean Drilling Program (IODP) Expedition 340T, marks the first time the geophysical properties of gabbroic rocks have successfully been measured directly in place, rather than via remote techniques such as seismic surveying.
With these measurements in hand, scientists can now infer how these hard-to-reach rocks will "look" on future seismic surveys, making it easier to map out geophysical structures beneath the seafloor.
"This is exciting because it means that we may be able to use seismic survey data to infer the pattern of seawater circulation within the deeper crust," says Donna Blackman of the Scripps Institution of Oceanography in La Jolla, Calif., co-chief scientist for Expedition 340T.
"This would be a key step for quantifying rates and volumes of chemical, possibly biological, exchange between the oceans and the crust."
Atlantis Massif sits on the flank of an oceanic spreading center that runs down the middle of the Atlantic Ocean.
As the tectonic plates separate, new crust is formed at the spreading center and a combination of stretching, faulting and the intrusion of magma from below shape the new seafloor.
Periods of reduced magma supplied from the underlying mantle result in the development of long-lived, large faults. Deep portions of the crust shift upward along these faults and may be exposed at the seafloor.
This process results in the formation of an oceanic core comp
|Contact: Cheryl Dybas|
National Science Foundation