Five measurements of in situ temperature were made in Hole 1246B using the APCT tool (Table T14; Fig. F25). Data were modeled using the software program TFIT (as described in the "Downhole Tools and Pressure Coring" in the "Explanatory Notes" chapter), using measured thermal conductivities (see "In Situ Temperature Data Reduction" in "Physical Properties" in the "Explanatory Notes"). Uncertainty in the extrapolated value of in situ temperature, as a result of subjective analyst picking of tp, ti and tf, is <0.02°C for these high-quality records. Uncertainty because of possible errors in measured values of thermal conductivity is also estimated to be ~0.02°C.
The resulting temperature estimates are shown in Figure F26. They show considerable scatter. Based on a decrease of ~2.2% in the apparent bottom-water temperature recorded after the measurement on Core 204-1246B-5H (Fig. F27), we suspect that APCT 12, which was used for all of these measurements, suddenly recalibrated itself during the second measurement. This observation led us to calibrate all of the APCT tools in an ice bath. Tools were placed in a trash can full of ice for at least 35 min. Results indicated serious calibration problems and are shown in Figure F26. A "corrected" temperature gradient for Site 1246 was calculated by assuming that APCT 12 required no correction for the first measurement and a correction of +2.5°C for the rest of the measurements (Fig. F26). This assumption leads to a temperature gradient that is consistent with other sites. APCT 12 was taken out of service, and APCT 11 was used for the rest of the leg. Comparison of data from APCTs 12 and 11 at Site 1244 suggests that APCT 12 was well calibrated prior to this unprecedented spontaneous recalibration (see "Downhole Tools and Pressure Coring" in the "Site 1244" chapter).
No in situ pressure measurements were made at this site.
No PCS cores were taken at this site.
No HYACINTH pressure cores were taken at this site.