The Arctic Coring Expedition: Drilling at the Top of the World

摘要

A fleet of icebreakers, under the auspices of the Integrated Ocean Drilling Program (IODP) successfully drilled in deep water of the central Arctic Ocean, near the North Pole (Fig. 1; Moran et al. in press). The Arctic Coring Expedition (ACEX) was the first expedition to drill in the central Arctic Ocean where heavy sea ice prevails year-round. The goal of ACEX was to drill and recover the first paleoceanographic sediment record from the central Arctic Ocean (Backman et al., in press). In August 2004, three icebreakers met at the ice edge, and headed north, as a convoy, to begin ACEX. This expedition successfully recovered core in water depths ranging between 1100 to 1300 m. The project involved over 200 people, including scientists, technical staff, icebreaker experts, ice management experts, ship's crew, and educators. At the drill site, temperatures hovered near 0° and occasionally dropped to -12°C. Ice floes 1 to 3 meters thick blanketed over 90% (i.e., > 9/10 ice cover) of the ocean surface, and ice ridges, several meters high were encountered where floes converged. The ice drifted at speeds of up to 0.3 knots and changed direction over short time periods, sometimes within an hour. The Swedish diesel-electric icebreaker Vidar Viking was converted into a drill ship for this expedition by adding a geotechnical drilling system that was capable of suspending over 2000 m of drill pipe through the water column and into the underlying sediments and by creating a hole in the hull (moonpool) capable of accommodating the drilling system. The two other icebreakers, a Russian nuclear vessel, Sovetskiy Soyuz, and the Swedish diesel-electric Oden, protected Viking by circling upstream in the flowing sea ice, breaking the floes into smaller pieces to protect the drilling vessel so that it could maintain station.