METHODS

The interstitial water chemical data from Sites 1003, 1005, 1006 and 1007 discussed in this paper are mainly based on shipboard measurements (Eberli, Swart, Malone, et al., 1997). The oxygen stable isotope data and some of the minor and trace element data are from other papers presented in DeCarlo and Kramer (Chap. 9, this volume) and Swart (Chap. 8, this volume). The reader is referred to these references for details on the analytical techniques. Several of the interstitial component shipboard and shore-based analyses are not discussed here, including those for lithium, fluoride, iron, and manganese. A large number of shipboard samples were processed during Leg 166 (generally >40 samples/hole) to allow for the detailed structure in the dissolved constituent profiles to be resolved. A summary of the shipboard pore-fluid results discussed in this paper is presented in Table 1.

The solid-phase data presented here were obtained from 190 samples collected from Sites 1007 and 1005. Approximately 200 mg of each sample was washed, crushed, dried, and weighed, and then placed in 40 mL of a 20% acetic-acid solution for 2 hr. The acid leachate was filtered through 0.2-µm preweighed filters and analyzed for Li⁺, Na⁺, Ca²⁺, Mg²⁺, Sr²⁺, Fe²⁺, Mn²⁺, and Ba²⁺ on an inductively coupled plasma-mass spectrometer (ICP-MS). Selected samples were analyzed for Ca, Mg, and Sr values using an inductively coupled plasma-optical emission spectroscope (ICP-OES). The concentration of Fe was determined using flame atomic adsorption (AA). All instruments were calibrated using a series of spiked standards in a 20% acetic-acid matrix. The filters containing insoluble residues were dried overnight at 50°C and reweighed to determine the weight percent of insoluble residue. Replicate analyses yielded results within 1 wt% for insoluble residues and within 5% for minor and trace elements.

Carbon isotope analyses of the DIC were performed on pore-fluid samples which were fixed with HgCl₂ and preserved in sealed glass ampules. Samples were injected into an evacuated serum bottle containing 0.5 cm³ of H₃PO₄. The CO₂ was removed by purging with He, and then analyzed for ¹³C in a continuous flow, stable isotope ratio mass spectrometer (Europa 20-20). The precision using this method was better than 0.1%.