METHODS

Samples of carbonate sediments (one per core) were taken in the shipboard sediment laboratory. At Woods Hole Oceanographic Institution (WHOI; USA), these samples were oven dried, gently crushed, soaked for 2 hr in a 3% Calgon-hydrogen peroxide solution, and washed over a 63-µm sieve with warm tap water (pH = 6). Wet samples were dried in an oven at 45°C for 2 hr. Cretaceous organic-rich mudstone ("black shale") samples were cut from core on the JOIDES Resolution catwalk and frozen shipboard at –80°C. Black shale samples were later freeze dried and partly crushed using a porcelain mortar and pestle. Following a test of cleaning procedures (see the "Appendix"), crushed black shale sediments were soaked in undiluted Clorox bleach for 2 hr, washed, and dried, and then soaked for 1 hr in undiluted bleach, washed, and dried.

For planktonics, single-species stable isotope analyses were made of 1 to 25 individual whole specimens. For benthics, 1 to 5 individuals of single species or mixed species were analyzed. Oxygen and carbon isotope ratios were measured on a Finnigan MAT 252 mass spectrometer with an automated Kiel carbonate device at WHOI. Instrument precision is ± 0.07‰ for ¹⁸O and ±0.03‰ for ¹³C. Results are reported relative to the Vienna Peedee belemnite (VPDB) isotope standard and are given in Table T1.

We estimated the age of our sample set through a combination of shipboard biostratigraphy and shore-based magnetostratigraphy (Erbacher, Mosher, Malone, et al., 2004). The time-scale is that of the Leg 207 shipboard party (see references therein).