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UW Researcher Part of Indian Ocean Expedition to Drill to the Earth’s Mantle

January 21, 2016
Two scientists examine the first piece of core recovered during the Indian Ocean expedition.
Professor Chris MacLeod (left), co-chief scientist from Cardiff University in the United Kingdom, and UW Associate Professor Mike Cheadle, a structural geologist, examine the first piece of core recovered during the Indian Ocean expedition.

Michael Cheadle describes drilling on the ocean floor similar to using a wet piece of spaghetti -- holding it on one end while trying to push the other end deep into a cake.

The University of Wyoming associate professor in the Department of Geology and Geophysics is part of a team of research scientists dealing with that degree of difficulty as they attempt what is akin to a journey to the center of the Earth -- drilling through the seafloor crust and into its mantle -- from the Indian Ocean.

Cheadle is one of 26 research scientists, including nine from the United States, aboard the JOIDES Resolution, or “JR” for short. The sea-going research vessel drills core samples and collects measurements from boreholes into the ocean floor, giving scientists a glimpse into Earth’s development.

Other researchers hail from China, Italy, the United Kingdom, France, Japan, India, Brazil, Germany, the Netherlands, Australia, South Korea, Poland and the Philippines.

“I'm one of the structural geologists who examine the entire core (samples) for features, like faults, to better understand how the Earth's crust deforms as it is made at mid-ocean ridges,” Cheadle explains. “We are drilling one of the largest faults in the world and, by better understanding how these faults work, we can better understand how and why earthquakes occur on big faults. And, the beauty of working on a large fault is it has removed the top of the crust, so we have less far to drill to get to the mantle, which is the main target of the expedition.”

Drilling and sampling the Earth’s mantle has been a major objective for geologists for more than 60 years, he says. The Indian Ocean expedition is at a point called Atlantis Bank, which was once an island, but has now subsided 700 meters below sea level.

Cheadle says the plan is to ultimately drill to a depth of 5 kilometers (3.1 miles). This will involve three drilling legs -- two conducted by the “JR” to get to a depth of 3 kilometers, followed by an expedition using the Chikyu, a Japanese drilling vessel.

“On this leg, we were hoping to get to about 1200-1300 meters (deep), but we are likely to only get to 800-900 meters, because we've had various problems,” he says.

Those problems have included having a technician, due to an eye infection, helicoptered off the ship. The vessel had to sail to the island of Mauritius, where a Medivac picked up the patient, who Cheadle reports is now fine.

“It's really difficult drilling deep. One always finds unexpected problems, because it's been done so little,” he says. “We are currently the fifth-deepest hole drilled in ocean crust.”

This marks the second time Cheadle has been part of a research expedition on this particular vessel. In fall 2012, he was part of a 26-member international research team that cruised to a deep scar in the floor of the Pacific Ocean. That mission entailed studying rocks sampled from below the seafloor in an effort to better understand how the Earth’s crust is formed.

In this latest expedition, Cheadle is one of a few researchers to get the first up-close look at the core samples.

“I'm one of the three people who get to touch the core first, because I have to decide how the core is cut into two halves,” he says. “One half is an archive half,  to be looked at and measured, but otherwise to be saved; and the other half is the working half, which we can sample and use to learn more about the rocks, such as their chemistry.”

“We look for clues in the rocks for how the fault works, and measure and catalog what we see,” Cheadle adds.

Cheadle says he will be aboard the “JR” until Jan. 30. During that time, he will conduct a live broadcast from the ship to one of his science classes for teachers in the UW College of Education.

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