Five types of downhole tools were employed at Site 1225. These were the Adara temperature shoe, the DVTP, the DVTP-P, the APC-M tool, and the PCS. Deployments of the first four tools are described in the following subsections; deployments of the PCS are discussed in Dickens et al. (this volume).
Six reliable determinations of downhole temperatures were made at depths between 0 and 303 mbsf in Hole 1225A using the Adara APC temperature tool or the DVTP (Table T8). As described in "Downhole Tools" in the "Explanatory Notes" chapter, in situ temperatures were estimated by extrapolation of the station data using thermal conductivities measured on adjacent cores to correct for the frictional heating on penetration. The 95% confidence intervals from the temperature fits are all <0.03°C. Testing of the probe tip thermistor on DVTP tool 2 showed that it read 0.38°C too high in the laboratory at ~19°C. Therefore, the temperature reading for 303.7 mbsf was adjusted down by 0.38°C. This changed the computed gradient by <0.1°C/km. The estimated in situ temperatures from both the Adara and DVTP define a gradient of 0.0174°C/m over the upper 303 m of sediment (Fig. F31). Extrapolating this temperature gradient yields a value of 6.97°C at the base of the hole. Multiplying the gradient by an average thermal conductivity of 0.89 W/(m·K) (see Fig. F29A and accompanying text in "Thermal Conductivity" in "Physical Properties") yields a conductive heat flow estimate of 15.5 mW/m2 at Site 1225. This value lies near the low end of global heat flow database values for this area (Pollock et al., 1993). The temperature data define a profile that is curved slightly downward compared to a linear profile. Possible interpretations of the observed curvature are discussed under "Thermal Conductivity" in "Physical Properties."
The APC-M tool was deployed in Hole 1225A continuously from Cores 201-1225A-5H through 14H. The recovered data from this run showed that the tool and data logger initially functioned correctly. Part way through the run after Core 201-1225A-8H, the data logger stopped recording. Upon recovery, the failure was attributed to a loose battery connection. The data from the APC-M tool will be analyzed postcruise.
The DVTP-P was deployed unsuccessfully twice in Hole 1225A at depths of 205.3 and 302.2 mbsf. The recorded data indicated that during both runs the nonindurated, fine-grained formation sediments clogged the filter. During the second run, there was a pressure drop to roughly atmospheric level during penetration. This failure was attributed to a leak in the line connecting the pressure transducer to the probe tip.