British Geological Survey, United Kingdom

Five drill sites are proposed on the ridge crest of the Lomonosov Ridge in the central Arctic Ocean. The sites are distributed between 88 degrees N and 81 degrees N in water depths ranging between 800 and 1415 m, and are all located in international waters. The ridge was rifted from the Kara/Barents Sea shelves during early Paleogene time and subsequently subsided to its present water depth. Since that time, sediments of biogenic, aeolian and ice-rafted origin have accumulated on the ridge crest. In our primary target area between 87 degrees N and 88 degrees N these sediments are about 450 m thick, indicating an average rate of sedimentation of approximately 10 m/my throughout the course of the Cenozoic. Sampling of these sediments would provide an unprecedented and unique opportunity to acquire a first-order knowledge about the paleoceanographic history of the central Arctic Ocean. Sampling of the underlying bedrock provides a similarly unique opportunity to decipher the tectonic history of the Lomonosov Ridge and the formation of the Eurasian Basin. The proposed program epitomizes both the spirit and the science of the new Integrated Ocean Drilling Program, calling upon the creative use of mission specific platforms and directly addressing a number of the key scientific questions raised in the IODP Initial Science Plan. Amongst scientific issues relating to "Environmental Change, Processes and Effects" are: - The long-term (50 Ma) climate history of the central Arctic Ocean, and its role in Earth's transition from one extreme (Paleogene greenhouse) to another (Neogene icehouse). - The shorter-term (Neogene) climate history, connecting the Neogene history of the Arctic Ocean to that of the North Atlantic Ocean at sub-millennial scale resolution. Scientific issues relating to "Solid Earth Cycles and Geodynamics" are: the composition and origin of the pre-Cenozoic bedrock underlying the sediment drape; and the rifting and subsidence history of the Lomonosov Ridge. Five sites distributed over six degrees of latitude are proposed, partly with overlapping goals, which will make the drilling expedition less vulnerable to severe local ice conditions. The major goals of this proposal can be achieved by completing one site to 450 mbsf. Should ice conditions at this site be prohibited, a suite of sites from other areas along the ridge can be drilled to achieve the proposed science