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Expedition 303/306 synthesis: North Atlantic climate1

J.E.T. Channell,2 T. Sato,3 T. Kanamatsu,4 R. Stein,5 and C. Alvarez Zarikian6


The sites occupied during Integrated Ocean Drilling Program Expedition 303/306 were chosen to recover late Miocene to Quaternary records of North Atlantic environmental variability at elevated mean sedimentation rates from locations appropriate for oxygen isotope (δ18O) and relative paleointensity (RPI) stratigraphies. The overall objective is to correlate these climate/​paleoceanographic records to two (ostensibly) independent global stratigraphic signals (δ18O and RPI), thereby enhancing stratigraphic resolution. One site at Orphan Knoll (Site U1302/U1303) provided a proximal record of Laurentide Ice Sheet instability for the Brunhes Chron. Three sites from the Eirik Drift (Sites U1305, U1306, and U1307) provided records of the strength and location of the Western Boundary Undercurrents well as monitors of Greenland Ice Sheet instability back into the Pliocene. Poor weather over the Erik Drift during the second phase of drilling (Expedition 306) precluded the planned return that would have further enhanced knowledge of the history of the drift. Three sites (U1308, U1312, and U1313) constituted reoccupations of classic paleoceanographic sites drilled in 1983 during Deep Sea Drilling Project Leg 94. Although poor weather compromised the record at Site U1312, the new drilling at Sites U1308 and U1313 provided complete sections to the Pliocene and late Miocene, respectively, that were not available from Leg 94. Site U1308 provided evidence for “Hudson Strait” Heinrich Events in the eastern North Atlantic from the end of the middle Pleistocene transition (~640 ka). One site on the central part of the Gardar Drift (Site U1314) and one site at the southern tip of the Gardar Drift (Site U1304) provided high-resolution deepwater paleoceanographic records that can be linked with shallower water drift sites in the Iceland Basin, drilled during Ocean Drilling Program Leg 162. Site U1315, located on the Vøring Plateau, was drilled to 179 meters below seafloor. Instruments to monitor seafloor temperature variations resulting from bottom current changes were installed with a circulation obviation retrofit kit to seal the borehole.

1 Channell, J.E.T., Sato, T., Kanamatsu, T., Stein, R., and Alvarez Zarikian, C., 2010. Expedition 303/306 synthesis: North Atlantic climate. In Channell, J.E.T., Kanamatsu, T., Sato, T., Stein, R., Alvarez Zarikian, C.A., Malone, M.J., and the Expedition 303/306 Scientists, Proc. IODP, 303/306: College Station, TX (Integrated Ocean Drilling Program Management International, Inc.).

2 Department of Geological Sciences, University of Florida, Gainesville FL 32611, USA.

3 Department of Earth Sciences and Technology, Akita University, Akita 010-8502, Japan.

4 Institute for Frontier Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology, Yokosuka 237-0061, Japan.

5 Alfred-Wegener-Institut für Polar und Meeresforschung, Columbusstrasse 2, 27568 Bremerhaven, Germany.

6 Integrated Ocean Drilling Program, Texas A&M University, 1000 Discovery Drive, College Station TX 77845-9547, USA.

Initial receipt: 17 November 2009
Acceptance: 15 March 2010
Publication: 30 June 2010
MS 303306-214