BACKGROUND AND OBJECTIVES

Site 1211 is located in lower bathyal (2907 m) water depth on the southern flank of the Southern High of Shatsky Rise. The site is at the location of DSDP Site 305. Thus, the stratigraphic sequence is known, although significant disturbance in Cenozoic and Upper Cretaceous sediments resulting from RCB drilling at Site 305 has blurred the signal of short-term events such as the PETM and the Eocene-Oligocene transition.

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 drilled sequence at Site 305 had a total depth of 640.5 m and reached the Hauterivian. The site contains a relatively thick sequence of Lower Cretaceous chalk and chert, overlain by Upper Cretaceous ooze and chert and Cenozoic ooze (Larson, Moberly, et al., 1975). A major unconformity was found between the middle Miocene and the upper Oligocene. Minor unconformities are thought to exist in the middle Eocene. Otherwise, biostratigraphic results (e.g., Bukry, 1975; Caron, 1975; Luterbacher, 1975) suggest a reasonably continuous sequence. Sites 305 and 1211 are located on seismic line TN037-17A (Fig. F1). Observation of the seismic profile shows a significant unconformity beneath the upper part of the Upper Cretaceous, probably the Campanian. Thus, it is likely that at least part of the Santonian-Cenomanian interval is missing at this site as proposed by Sliter (1992) based on a reevaluation of planktonic foraminiferal biostratigraphy.

Site 1211 is the second deepest site in the Shatsky Rise depth transect. The shallowest site, Site 1209 at 2387 m, is ~500 m shallower than Site 1211; the deepest site, Site 1208 at 3346 m, is ~400 m deeper. The goal of coring at Site 1211 is to recover with triple APC coring a complete and undisturbed record of the Site 305 sequence. As part of this depth transect, drilling at Site 1211 addresses a number of leg-related objectives. The sediments recovered at this site will be used to

1. Determine the evolution of surface and deepwater properties through the Late Cretaceous and Paleogene using shore-based stable isotope studies and microfossil assemblage investigations. In particular, we are interested in the onset and demise of the Cretaceous "greenhouse" and the onset of Antarctic glaciation in the Eocene.
2. Determine the nature of chemical (i.e., CCD, nutrients, and oxygenation) and physical oceanographic changes (temperature gradients) during transient climatic events, such as the E/O boundary, the PETM, late Paleocene and early Eocene hyperthermals, and the MME.
3. Compare fluctuations in the CCD through time with other records from Shatsky Rise and interpret them in a paleoceanographic framework.
4. Shed light on the nature and origin of orbital cycles using geochemical and biotic data.
5. Refine Cretaceous and Paleogene timescales by improving correlations between the geomagnetic polarity timescale and low-latitude biostratigraphies and generating high-resolution orbital stratigraphies in intervals with prominent cyclicity.