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doi:10.2204/iodp.proc.320321.105.2010

Downhole measurements

Heat flow

Four APCT-3 temperature measurements in Hole U1333B ranged from 2.52°C at 26.7 m to 4.55°C at 83.7 m (Table T34), giving a geothermal gradient of 37.9°C/km (Fig. F30). The bottom water temperature was 1.44°C, based on the average of the minimum temperature in the four APCT-3 temperature profiles. Thermal conductivity under in situ conditions was estimated from laboratory-determined thermal conductivity using the method of Hyndman et al. (1974) (see "Physical properties" in the "Methods" chapter). The calculated in situ values are up to 2.2% below the measured laboratory values. Thermal resistance was then calculated by cumulatively adding the inverse of the in situ thermal conductivity values over depth intervals downhole (Fig. F30). A heat flow of 42.3 mW/m² was obtained from the linear fit between temperature and thermal resistance (Fig. F30) (Pribnow et al., 2000), which is similar to Site 1220 to the west but roughly 20 mW/m² less than nearby Sites 1218, 1219, and U1332.

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