On 23 May, the WSTP was lowered to a depth of ~3016 mbrf, or 2 m above seafloor, for a 38-min station before drilling operations began in Hole 1268A (Fig. F97A). A temperature-time-series of ocean bottom water and a water sample were obtained for microbiology studies (see "Seawater and Water Samples and Atmospheric Data" in "Microbiology"). The temperature-time series shows a gradual increase for ~8 min before the water-sampling valve opened, followed by a 2-min period with no sampling of temperature data, one stationary temperature reading, another 2-min interval with no temperature readings while the water-sampling valve was closing, and a 9-min period before the tool began its ascent to the rig floor (Fig. F97B).
The ocean bottom water temperature increased from 2.91° to 3.04°C, or a rate of ~0.0003°C/s over the 8-min time interval before the water-sampling valve was opened (Fig. F97C). These temperatures are consistently higher than 2.81°C, which was recorded with the concentration/temperature/depth probe between 3012 and 3019 mbsl by the Shinkai 6500 submersible during Dive 427 in the same area in 1998 (P. Kelemen, pers. comm., 2003). Either tool drift or a steady warming of the bottom water may have caused this increase in temperature. The highest temperature was recorded after the water-sampling valve closed and the tool resumed recording temperatures (Fig. F97B). Bench tests during Leg 209 showed a temperature increase after the valve was closed. Hence, this anomalous point is probably related to heating due to the added voltage needed to close the valve. The high value was 3.78°C, or 0.69°C higher than the previous temperature reading. A temperature anomaly was also recorded during a 2.8-min period after the valve closed, when values increased from 3.28° to 3.68°C (Fig. F97B). This anomaly may have been caused by (1) tool malfunction, (2) frictional heating caused by inadvertent contact with the seafloor or the drill pipe because of heave conditions, or (3) slightly warmer fluids emanating from the seafloor.