Five reliable determinations of downhole temperatures were made at Site 1176 using the Adara APC tool and the Davis-Villinger temperature probe (DVTP). Table T19 summarizes the deployments, and the temperature data are shown in Figures F27 and F28. In situ temperatures were estimated by extrapolation of the station data to correct for the frictional heating on penetration assuming a thermal conductivity of 1.0 W/(m·°C).
Two additional measurements were attempted with the DVTP, and one additional measurement was taken with the water-sampling temperature probe (WSTP) during a water sampling run. At these three stations, temperatures were anomalous, despite reasonable decay curves (Fig. F29). Infiltration of seawater from the bottom of the borehole into permeable or cracked formation provides the most plausible explanation for these data.
The mudline temperature and the five upper measurements define a linear gradient of 0.056°C/m in the upper 248.5 m (Fig. F30). For thermal conductivities of 1.0 W/(m·°C), vertical conductive heat flow at Hole 1176A would be 56 mW/m2. Pressures were also recorded during the DVTP-P deployments at 248.5, 295.7, and 383.5 mbsf. The pressure record from the successful run, which was at 248.5 mbsf, is shown in Figure F31. As noted in "In Situ Temperature and Pressure Measurements" in the "Explanatory Notes" chapter, postcruise modeling and processing is required to estimate in situ pressures.