Table T11. Chemical analyses of borehole fluids, Hole 1256D, and nearby bottom seawater collected with the WSTP, Expedition 309. (Continued on next page.)
| Core, section, interval (cm) |
Sample description |
Depth (mbsf) |
Temperature (°C) |
Salinity | pH (25°C) |
Alkalinity (mM) |
Cl (mM) |
SiO2 (µM) |
PO4 (µM) |
NH4+ (µM) |
|---|---|---|---|---|---|---|---|---|---|---|
| Borehole fluid (309-1256D-75R-1, 2–3) | ||||||||||
| WST 1 | Ti coil | 724.6 | 67.6 | 35.5 | 545 | |||||
| WSO 1 | Overflow | 724.6 | 67.6 | |||||||
| WSO 1 | Overflow (duplicate) | 724.6 | 67.6 | |||||||
| WSO 1 | Overflow (average) | 724.6 | 67.6 | 26.0 | 7.4 | 1.58 | 345 | BDL | 214 | |
| Borehole fluid (309-1256D-75R-1, 1–2) | ||||||||||
| WST 2 | Ti coil | 712.6 | 66.3 | 35.0 | 564 | |||||
| WSO 2 | Overflow | 712.6 | 66.3 | |||||||
| WSO 2 | Overflow (duplicate) | 712.6 | 66.3 | |||||||
| WSO 2 | Overflow (average) | 712.6 | 66.3 | 35.0 | 7.4 | 0.85 | 553 | 169 | BDL | 25 |
| Preferred composition of borehole fluid | 712.6 | 67 | 35.0 | 7.4 | 0.85 | 564 | 169 | BDL | 25 | |
| Bottom seawater (3633 mbsl) (309-1256D-75R-1, 0–1) | ||||||||||
| WST 3 | Ti coil | –2 | 1.9 | 35.0 | ||||||
| WSO 3 | Overflow | –2 | 1.9 | |||||||
| WSO 3 | Overflow (duplicate) | –2 | 1.9 | |||||||
| WSO 3 | Overflow (average) | –2 | 1.9 | 34.0 | 7.8 | 2.54 | 539 | |||
| Preferred composition of bottom seawater | 0 | 1.9 | 35.0 | 7.8 | 2.54 | 539 | 102 | |||
| IAPSO | 35.0 | 8.2 | 2.31 | 560 | 102 | 2.3 | 31 | |||
| Best estimate of uppermost basement fluid at Site 1256 | 250 | 35 | 34.0 | 7.4 | 0.86 | 540 | 92 | |||
Notes: APCT tool temperature measurements have been adjusted to match the readings of the externally calibrated TAP tool. IAPSO standard seawater concentrations provided for reference (Summerhayes and Thorpe, 1996). WST = Ti coil sample from WSTP, WSO = overflow sample from WSTP. ICr = ion chromatography. ICP = inductively coupled plasma spectrometry. BDL = below detection limit.
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