BACKGROUND AND OBJECTIVES

Site 1212 is located at 2682.5 m water depth on the southwestern flank of the Southern High of Shatsky Rise. The site is located close to DSDP Site 47. Thus, the stratigraphic sequence is known, although significant disturbance in Cenozoic and Upper Cretaceous sediments resulting from RCB drilling at Site 47 has blurred the signal of short-term events, such as the PETM and the K/T boundary.

The drilled sequence in Hole 47.2 had a total depth of 129.2 m and reached the upper Maastrichtian. The site contains a relatively thick lower-middle Eocene to uppermost Maastrichtian section (Fischer, Heezen, et al., 1971). This section was an integral part of the data set used by Douglas and Savin (1971) to derive one of the first late Maastrichtian to Cenozoic paleotemperature curves. A major unconformity was found between the upper Miocene and the upper-lower Eocene. Other, more minor unconformities may exist in the section, but they are difficult to detect because of the major drilling disturbance present in the section. Biostratigraphic results from Hole 47.2 (e.g., Douglas, 1971) suggest a reasonably continuous sequence across intervals such as the K/T boundary.

Site 1212 is in the middle of the Shatsky Rise depth transect. The shallowest site, 1209 at 2387 m, is ~300 m shallower than Site 1212; the deepest site, 1208 at 3346 m, is ~670 m deeper. The goal at Site 1212 was to recover with double APC coring a complete and undisturbed record of the Site 47 sequence. As part of this depth transect, drilling at Site 1212 addresses a number of leg-related objectives. The sediments recovered at this site will be used to

  1. Reconstruct changes in the properties of surface and deepwaters and vertical gradients through the Cretaceous and Paleogene using biotic and stable isotope studies;
  2. Determine long-term climate changes during the onset and demise of the Cretaceous "greenhouse" and the onset of Antarctic glaciation in the Eocene;
  3. Shed light on the nature of chemical (i.e., calcite compensation depth [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;
  4. Determine fluctuations in the CCD through time and interpret them in a paleoceanographic framework;
  5. Improve understanding of the origin of orbital cycles in the sedimentary record using geochemical and biotic data; and
  6. Improve Cretaceous and Paleogene timescales by including correlations between the geomagnetic polarity timescale and low-latitude biostratigraphies.

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