Drilling for Insight in Antarctica

Polar Expeditions Shed Light on Global Warming

The Antarctic Geological Drilling (ANDRILL) Program drilled to a new record depth of 1,000 meters below the seafloor from the site on the Ross Ice Shelf near Scott Base in Antarctica.

September, 2007. In the relative warmth of an Antarctic spring, when the coastal temperature rises to the freezing point, a 60-ton drilling platform is towed sledgelike to its operating site across floating sea ice. No more than 25 feet of ice separate the rig and the chill, hypersaline waters of McMurdo Sound. Fifteen hundred feet below the ice is the sea floor, and below that, layers of rock built of millennia of sedimentary deposits. The rig is the heartbeat of a scientific enterprise. And, with the help of Apple technology, its drill cores will yield insights into the changing climate of our planet.

This is the Southern McMurdo Sound Project (SMS), the second Antarctic data-gathering project for ANDRILL (ANtarctic geologic DRILLing), a scientific initiative funded by Germany, Italy, New Zealand and the United States. ANDRILL is focused on uncovering the geologic history of the Antarctic continent. Its findings have meaning for every one of us.

Antarctica, bigger than Europe, bigger than Australia, bigger than the U.S., stores a huge percentage of the earth’s fresh water in its coast-to-coast freezer. The oceans meet here, and the dense, cold water that flows from under Antarctica’s ice sheets creates currents that affect water movement and weather patterns around the earth. Melting ice in Antarctica raises sea levels worldwide. What happens here affects us all.

Sea levels are currently rising at a rate of a tenth of an inch per year. These and other environmental phenomena, including changes in atmospheric gases and global temperature levels, are taken by most scientists as unmistakable indications that the earth is warming. The International Polar Year (2007-2009), of which ANDRILL is a part, is a collaborative effort by scientists to examine the geologic history of the polar regions and their current behavior to provide perspective on these changes.

“We’re trying to recover the geologic record of ice shelf and ice sheet behavior in Antarctica,” says ANDRILL staff scientist Dr. Richard Levy. “We really have very little evidence of how the ice sheet behaved in the past. We want to know how the ice shelf and the ice system have responded to climate changes over the last 15-20 million years. To do that we have to drill through the ice and get to the sediment layers that are preserved in the basins that surround the continent.”

The Core of the Matter: Displaying the Record of the Sediments

The Southern McMurdo Sound Project will be ANDRILL’s second Antarctic drilling project. It will apply the same technology and methods as the first ANDRILL expedition — the McMurdo Ice Shelf Project (MIS), begun late in 2006 and completed early in 2007. MIS drilled to 4200 feet below the seafloor, starting with wider diameter pipe (the riser), then using successively smaller drill pipes inside the larger pipes, deploying a total of 20,000 feet of pipe. The team drilled 20 feet at a time, pulling up a 3.5-inch-diameter core in the first stage — a half-hour procedure — and drilled again. At greater depths, where they used smaller-diameter pipe, they pulled longer, narrower cores — roughly 30 feet long and 1.5 to 2.0 inches in diameter. Curators at the drill site washed the cores and cut them to three-foot lengths. The cores were then transported to McMurdo Station, where they were sliced in half longitudinally and protected with PVC liners. One half was boxed and archived; the other went to the sedimentology room. Each was marked to show the top end and the depth at which it was cut.

Dr. Larry Krissek (The Ohio State University) in front of Corelyzer. Photo taken by Betty Trummel, Humann Elementary School, Crystal Lake, Illinois.

Cores were scanned with a high-resolution camera. The digital image data was fed into a Corewall core-analysis system that included an Intel-based Mac Pro workstation and two 30-inch Apple Cinema Displays in an 8-megapixel tiled configuration. Corelyzer, a visualization tool that is part of the Corewall software suite, enabled ANDRILL scientists to enlarge images of the cores from their original diameters (1.5 to 3.5 inches) up to 30-inch diameters and make annotations.

“I think Corelyzer is considered a major breakthrough for scientists who need to look at visualizations of drill cores,” says Dr. Jason Leigh, Director of the Electronic Visualization Laboratory (EVL), where Corewall was developed. “Formerly, they would split the cores, take pictures of them, and pretty much never touch or see the core again — and they couldn’t look at the imagery at full resolution either. We enable them to see those cores again as they were first obtained and do much more with them.”

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