MEASUREMENT OF MARINE GEOTHERMAL HEAT-FLOW BY A MULTI-PENETRATION PROBE WITH DIGITAL ACOUSTIC TELEMETRY AND INSITU THERMAL-CONDUCTIVITY

The design and use of a marine heat probe with capability for measuring thermal conductivity insitu with high accuracy, and providing digital acoustic transmission of data to the ship, is described. The instrument employs the 'violin bow' strength member and parallel sensor string configuration suggested by C. R. B. Lister. Several hundred measurements have been made in the deep ocean on multipenetration or 'pogostick' profiles using a 3 m probe and in deep inlets of western Canada using a 7 m probe. The insitu thermal conductivity technique using a calibrated heat pulse has been studied in detail through laboratory calibration of the probe in materials of known conductivity, through numerical models, and through comparison of insitu measurements with needle probe measurements on sediment cores taken from the same sites. The insitu technique permits a conductivity accuracy of better than ±5% with a recording time of 7 minutes following 7 minutes in the bottom to establish the geothermal gradient. The pulse heating is also more energy efficient than the conventional continuous heating technique. © 1979 D. Reidel Publishing Company.