During a recent National Science Foundation (NSF)-funded research expedition aboard the scientific drill ship JOIDES Resolution, two new hot springs were created on the seafloor. This event reactivated an ancient hydrothermal system which produced extensive mineral deposits on or just below the ocean floor.
A group of 25 scientists from nine countries was part of an Ocean Drilling Program (ODP) research expedition to study active seafloor hydrothermal systems and the rich metal deposits they often produce. The ship drilled about 150 miles west of Vancouver Island, Canada, when the creation of these new vents occurred.
Although water as hot as 286 degrees C (547F) was actively being expelled from the seafloor within a few miles of the drilling location, ODP research focused on sampling the deposits formed by older, now inactive vents. "Natural hot springs on the seafloor are formed when seawater circulates through hot volcanic rocks, often located where new oceanic crust is being formed," explains Bruce Malfait, director of NSF's ocean drilling program. "Submarine hot springs are in the spotlight of such intense study because they are places where deposits rich in iron, copper, zinc, and other metals form."
"The metal deposits are of great interest to us not so much because they form a metal resource on the seafloor, but because of what they can tell us about how metallic ore deposits that we mine on land were formed millions of years ago," adds Robert Zierenberg, a researcher with the University of California, Davis, and co-chief scientist on this expedition. "Many of these metal deposits were originally created on the seafloor and have been pushed up onto the continents as the Earth's plates collide."
Scientists onboard the JOIDES Resolution inspected the site of the new hydrothermal vents by lowering an underwater camera to the seafloor. The new hydrothermal vents provide an unprecedented opportunity for scientists to study the life cycle of a seafloor hot spring and its associated biological community. Naturally occurring hydrothermal vents are known to have limited life spans, but how long any given vent lasts, how it evolves, and how the biological community it supports evolves is largely unknown. One of the biggest mysteries is how vent animal communities manage to migrate from one vent to another. Melanie Summit, a microbiologist at the University of Washington, says, "We can now start from time zero and watch how these sites become colonized. This is our first opportunity to see how a new hydrothermal vent, and the animal communities that thrive in these environments, grow and change with time."
NSF has responded rapidly to scientists' requests to revisit this area of the Northeast Pacific in the near future. "This month, scientists will use the research vessel Thomas Thompson, outfitted with a robotic vehicle operated from the ship, to study the geology, chemistry, and biology of these new hydrothermal vents," says Dave Epp, acting director of NSF's marine geology and geophysics program.
The international research team will install instruments in the drill holes to monitor temperature and pressure changes during the next several years. The data will be stored in computers on the seafloor and will be recovered in the future when remotely operated vehicles (ROVs) or research submersibles visit these sites. Scientists will then examine the records to see how events like nearby earthquakes and volcanic eruptions affect the flow of hot water from the vents.