UW Researchers to Explore Pacific Ocean Floor to Understand History of Earth’s Crust
Michael Cheadle and Barbara John, professors in the University of Wyoming Department of Geology and Geophysics, will soon set sail, but it won’t be a leisurely vacation as husband and wife.
The two are part of a 26-member international research team that will cruise to a deep scar in the floor of the Pacific Ocean. Their mission: to study rocks sampled from below the seafloor in an effort to better understand how the Earth’s crust is formed.
The cruise is part of the Integrated Ocean Drilling Program United States Implementing Organization (IODP-USIO), a multinational research project that operates up to three research vessels that sail the world’s oceans. The ships drill bore holes to collect samples of rock and sediment from below the seafloor to address questions about geology, climate, oceanography and natural hazards, including earthquakes. The U.S., Japan, Europe and several other countries are involved in the 50-day, multimillion-dollar operation, funded by the National Science Foundation’s (NSF) Division of Ocean Sciences.
The JOIDES Resolution, or “JR” for short, is the name of one of the sea-going research vessels that drills core samples and collects measurements from boreholes into the ocean floor, giving scientists a glimpse into Earth’s development.
“We, as a team, will be responsible for looking at every centimeter of the core that’s recovered,” John says. “Mike and I will be looking at the geology of the core. Other scientists will be measuring physical properties, magnetization or the conductivity.
“Mike and I are geologists, trying to understand what the rocks are,” she continues.
John says they will measure the fractures and faults, and examine the crystals that make up the rocks. By looking at their chemistry, composition and shapes, the crystals tell a story and can offer clues as to how and when the ocean crust was formed.
Cheadle says he and his wife, like the other researchers aboard, will input their findings into a computer database, create spreadsheets and diagrams, and pen a report on their findings. Written reports from all of the researchers will be culled together and published in a book, John says.
At the ocean’s crust
John and Cheadle will leave Laramie Dec. 8, to join the ship in Costa Rica. After loading personnel, provisions and fuel, the “JR” will leave Puntarenas Dec. 13, and sail west for about four days. There, it will stop and sit for 40 days, drilling into scar in the Pacific seafloor referred to as the “Hess Deep.” It is one of a few locations in the world’s oceans where a large fault cuts a hole into the oceanic crust, Cheadle says. The fault creates a “window” and allows access to the lowermost part of the crust, which is the target of the expedition.
The Galapagos Islands lie to the east of the Hess Deep, John says.
John and Cheadle have previously made similar research cruises aboard the “JR” but, separately and in expeditions to the Atlantic and Indian oceans. This is their first foray into the Pacific together on the drillship.
The drill string, which has a giant drill bit attached, has to descend through nearly 5 kilometers of water before it reaches the seafloor. From there, it will drill 200-300 meters in the crust, which may bore down 3-4 kilometers into the crust, which is up to 7 kilometers thick. To keep the ship steady and the drill string from breaking during the 24/7 operations, the vessel includes a set of propellers that surrounds the bottom of the hull.
“These thrusters act like little egg beaters,” John says of the propellers. “They’re all computer controlled to keep the ship over the hole so you don’t break the drill string. You have to keep the ship in position.”
With advancement of the drill string every 5-10 meters, core is brought to the surface and onto the ship’s deck. The new core is laid out in trays and cut in half for the scientists to observe. Scientists often work up to 18-hour days to keep up with the haul.
The world’s oceanic crust -- which makes up 70 percent of the Earth’s surface -- is formed at mid-ocean ridges, Cheadle says. At these ridges, volcanoes sit above magma chambers fed from below by the melting mantle. Oceanic crust is made from the freezing of this molten magma, he says.
“What we’re trying to drill is the bottom part of the crust, the last kilometer. This is where it might get exciting,” Cheadle say. “You never know what’s going to happen. It’s really ‘discovery science.’ For the last 50 years or so, the Holy Grail is to drill through the boundary of the crust and the mantle below. It wouldn’t surprise me if we got mantle rocks. If so, you’ll see press releases about this published around the world.”
“We know more about the backside of the moon than we do about what’s beneath the ocean,” John says.
From a practical standpoint, Cheadle says the ocean crust is home to a number of mineral ores, including copper, gold, lead and zinc.
“We are using up our resources on land. People will begin to mine the sea floor. That will be all that’s left,” he says.
Longtime program adds outreach
The program began more than 50 years ago under previous incarnations, and was originally called the Deep Sea Drilling Program, Cheadle says.
“In those days, the program was about as big as the Apollo space program. They (researchers) received telegrams from President Kennedy,” Cheadle says.
In today’s world, the “JR” will conduct correspondence of its own, using the latest technology to disseminate information about the expedition to the public.
The cruise, dubbed “Expedition 345,” will include a full-steam-ahead outreach effort. Three outreach officers -- a N.Y. Times freelance journalist, a high school science teacher and a marine biologist -- are scheduled to sail with the crew. The trio will write daily blogs and press releases, send photos, and post updates to Facebook and Twitter. In addition, school groups can sign up for live classes that can be delivered, via Skype, directly from the ship to the classroom and ask questions of the researchers.
“It is totally possible for Laramie High School students to ask us questions,” Cheadle says.
Both John and Cheadle said they could end up being taped on the ship’s 24-hour video feed and they may contribute blogs or answer questions from the public.
For access to the ship’s education portal, go to http://joidesresolution.org/.
While it remains to be seen how curious the public will be, John and Cheadle are itching to unlock the mysteries of ocean crust.
“I’m just curious how the crust is built. Is it very quickly, steady or jerky?” John asks rhetorically.
Michael Cheadle, a UW associate professor of geology, holds up a core sample composed of mantle in the JR’s core lab. Cheadle and his wife, fellow professor Barbara John, will be part of an international research team that will study core samples in the Pacific Ocean Dec. 13-Feb. 14. (Benoit Ildefonse Photo)