BACKGROUND AND OBJECTIVES

Site 1210 is located in middle bathyal (2573 m) water depth on the southern flank of the Southern High of Shatsky Rise. According to the reconstruction of Nakanishi et al. (1989), basement underlying the site was formed in the latest Jurassic within Magnetochron M20 (~145 Ma). The site is located on seismic line TN037-17A. Because of the proximity of this site to the seismic lines that are calibrated with drill holes, the seismic units of Sliter and Brown (1993) can be identified with a fair amount of certainty. Seismic Unit 1 (Neogene) is relatively condensed, and Units 2 (Paleogene) and 3 (Upper Cretaceous) are moderately expanded. The paleodepth of this site is ~750 m in the early Maastrichtian based on the estimate of Barrera et al. (1997) for Site 305; however, this estimate is based on the assumption of subsidence rates for normal crust. In actuality, the subsidence history of Shatsky Rise may have been very different than that of normal crust, with much of the subsidence taking place in the first few tens of millions of years (e.g., McNutt et al., 1990).

Site 1210 is the second shallowest site in the Shatsky Rise depth transect. Site 1209 is at 2387 m, ~200 m shallower than Site 1210; the deepest site, Site 1208 at 3346 m, is some 770 m deeper than Site 1210. As part of this depth transect, drilling at Site 1210 addresses a number of leg-related objectives. The sediments recovered at this site will be used to

1. Constrain the character and stability of intermediate- and deepwater circulation and vertical thermal gradients through the Late Cretaceous and Paleogene.
2. Determine long-term climate changes in the Late Cretaceous and Paleogene, in particular, in the onset and demise of the Cretaceous "greenhouse" climates and the onset of Antarctic glaciation in the Eocene.
3. Determine the changes in surface and deepwater biotas over long and short timescales during the Cretaceous and Paleogene and relating them to oceanographic changes.
4. Elucidate the origin of transient climatic events such as the Eocene/Oligocene boundary, the PETM, late Paleocene and early Eocene hyperthermals, and the MME. The depth transect will also constrain changes in temperature, CCD, nutrients, and oxygenation during these events.
5. Determine fluctuations in the CCD through time, compare them to other records from the North Pacific as well as from other ocean basins, and interpret them in a paleoceanographic framework.
6. Improve understanding of the origin of orbital cycles in the sedimentary record.
7. Continue to refine Cretaceous and Paleogene timescales. We expect to derive a reliable magnetostratigraphy. This will allow us to refine correlations between the geomagnetic polarity timescale and low-latitude biostratigraphies. In intervals with prominent cycles, we will be able to derive high-resolution orbital stratigraphies.