Sea-ice conditions force Cape Roberts drill team to withdraw early
Disappointed researchers abandoned work on Saturday 25 October 1997 at the first drill hole site for the Cape Roberts Project, an international effort to learn about the climate history of Antarctica by studying sediment cores from the ocean floor. A two-day storm in the southern ocean broke the sea ice around the drilling platform to within about a kilometer of the rig. In accordance with established safety procedures, drillers were evacuated from the rig when conditions were deemed dangerous. An aerial reconnaissance of the ice on which the drilling platform had been constructed revealed fresh sea-ice cracks and a risk of further ice movement. When the storm had passed, 20 drillers and support staff, working around the clock, disassembled the rig and pulled it, along with other equipment, 25 kilometers back to the base camp close to shore.
Dennis Peacock, section head,
Antarctic Sciences Section of the Office of Polar Programs (seated near the window), and Steve Kottmeier
of Antarctic Support Associates (standing next to Peacock), examine the core retrieved on 17 October by
the Cape Roberts Project drillers.
Before the site had to be abandoned, it produced one core. About 30 meters of Quaternary sedimentary cover, which represents the recent advances and retreats of ice, and more than 90 meters of Miocene sediments were recovered on 17 October. The Miocene sediments fill a gap in current records, so they will be valuable for scientists trying to construct a picture of paleoenvironmental evolution. Working at the drill site and at McMurdo Station, a team of about 50 scientists from 28 institutions around the world has been studying the core samples, some as old as 17 to 22 million years, since their retrieval.
Section of the core recovered on 17 October. It was
1:30 a.m., but it was broad daylight, when the first core emerged, and the temperature was about
-18°C. When the first core came up, project director Peter Barrett knew that the team faced a race
against the spring thaw to extract as much core as possible while temperatures were still low enough to
keep the sea-ice beneath the drilling platform stable. He had hoped the drilling could continue until late
November, but unseasonably warm temperatures and punishing storms threatened to break apart the sea
ice much earlier in the season. For the safety of the crew and equipment, the drilling site was abandoned on
25 October.
The Cape Roberts team had hoped to drill a second hole closer to shore to reach ocean-floor sediments expected to be 30 to 70 million years old, but the unseasonably warm temperatures and southerly storms caused the team to abandon drilling for the rest of the season. Chief scientist Peter Barrett of Victoria University in Wellington, New Zealand, praised the hard work of the project team in establishing the camp in bitter weather and recovering the core sample from a difficult hole, and he expressed regret that in the end, the team had to abandon the site on short notice. "We have made some significant finds," Barrett said, "proven that the technology works in this environment, and built operational science teams that put us in good stead for next year." Another hole is planned to be drilled in October and November 1998.
For more information, see the Antarctica New Zealand Web site for press releases, and go to http://www.erim.org/CES/CapeRoberts for RADARSAT and other photos of the area.