Abstract:
Impacts of the Earth's warming climate are increasingly evident n the highly-sensitive polar regions. In the Arctic, the substantial loss of sea ice has the potential for global impact through loss of albedo. The history of this albedo in the paleo-record was recovered during the first scientific drilling expedition to the central Arctic Ocean. The Integrated Ocean Drilling Program's (IODP) Arctic Coring Expedition (ACEX) 302 recovered sediment cores that include a record of the past Arctic climate from over four hundred meters beneath the seafloor in water depths of ca. 1300 m at the top of the world, only 250 km from the North Pole. The destination of ACEX was the Lomonosov Ridge, hypothesized to be a sliver of continental crust that broke away from the Eurasian Plate ca. 50 Ma. As the Lomonosov Ridge moved away from the Eurasian plate and subsided, sedimentation began, continuing to the present, leaving a continuous paleoceanographic record. The elevation of the ridge above the surrounding abyssal plains ( nearly equal 3 km) ensures that sediments on top of the ridge are isolated from turbidites and are likely of purely pelagic origin. The primary ACEX objective was to recover this continuous sediment record and basement rocks by drilling and coring from a stationary drillship. The biggest challenge facing ACEX was maintaining the drillship's location while drilling and coring in moving, heavy sea ice. Sea ice cover over the Lomonosov Ridge moves with the Transpolar Drift and is affected by local responses to wind, tides, and currents. Prior to ACEX, the high Arctic Ocean basin, known as "mare incognitum" to the scientific community, had never been deeply cored before because of these challenging sea ice conditions.