Proceedings of the Integrated Ocean Drilling Program 302: Arctic Coring Expedition (ACEX)

• Main Authors: Backman, Jan, Moran, Kate, McInroy, David, Brinkhuis, Henk, Clemens, Steven C., Cronin, Thomas, Dickens, Gerald R., Eynaud, Frédérique, Gattacceca, Jérôme, Jakobsson, Martin, Jordan, Richard W., Kaminski, Michael A., King, John, Koç, Nalân, Martinez, Nahysa E., Matthiessen, Jens, Moore, Jr., Theodore C., Onodera, Jonaotaro, O'Regan, Matthew, Pälike, Heiko, Rea, Brice, Rio, Domenico, Sakamoto, Tatsuhiko, Smith, David C., St. John, Kristen, Stein, Ruediger, Suto, Itsuki, Suzuki, Noritoshi, Takahashi, Kozo, Watanabe, Mahito, Yamamoto, Masanobu
• Other Authors: Integrated Ocean Drilling Program
• Format: Book
• Language: unknown
• Published: Integrated Ocean Drilling Program Management International, Inc. 2006
• Subjects: Integrated Ocean Drilling Program; IODP; Expedition 302; Site M0001; Site M0002; Site M0003; Site M0004; ACEX; Arctic Coring Expedition; Lomonosov Ridge; Arctic Ocean; North Pole; Sea ice
• Online Access: https://doi.org/10.5281/zenodo.10777514; https://doi.org/10.2204/iodp.proc.302.2006

The first scientific drilling expedition to the central Arctic Ocean, Integrated Ocean Drilling Program Expedition 302, Arctic Coring Expedition (ACEX), recovered sediment cores to 428 m below seafloor (mbsf) in water depths of ~1300 m, 250 km from the North Pole. Expedition 302’s destination was the Lomonosov Ridge, hypothesized to be a sliver of continental crust that broke away from the Eurasian plate at ~56 Ma. As the ridge moved northward and subsided, marine sedimentation occurred and continues to the present, resulting in what was anticipated from seismic data to be a continuous paleoceanographic record. The elevation of the ridge above the surrounding abyssal plains (~3 km) ensured that sediments atop the ridge were free of turbidites. The primary scientific objective of Expedition 302 was to continuously recover this sediment record and to sample the underlying sedimentary bedrock by drilling and coring from a stationary drillship. The biggest challenge during Expedition 302 was maintaining the drillship’s location while drilling and coring in 2–4 m thick sea ice that moved at speeds approaching 0.5 kt. Sea-ice cover over the Lomonosov Ridge moves with one of the two major Arctic sea-ice circulation systems, the Transpolar Drift, and responds locally to wind, tides, and currents. Until now, the high Arctic Ocean Basin, known as “mare incognitum” within the scientific community, had never before been deeply cored because of these challenging sea-ice conditions. Initial results reveal that biogenic carbonate is present only in the Holocene–Pleistocene interval. The upper 198 m represents a relatively high sedimentation rate record of the past 18 m.y. composed of sediment with ice-rafted debris and dropstones, suggesting that ice-covered conditions extended at least this far back in time. A hiatus at 193.13 mbsf spans 25 m.y. from the early Miocene to the middle Eocene (~18–43 Ma). The sediment record during the middle Eocene is of dark, organic-rich biosiliceous composition. Isolated pebbles, interpreted ...