Abstract:

To investigate the geothermal distribution of the northern margin of the South China Sea, EWING-type heat flow probe was employed to measure the temperature gradient of the marine sediments in three regions, and sediment samples were cored for thermal conductivity with a thermal conductivity meter TK04. After a series of detailed data processing, the heat flow data of three representative sites HD343, HS82 and HX129 were obtained. The analyses show that it is necessary for EWING-type heat flow probe to correct the original temperature data for logger offsets and compute equilibrium temperatures for each logger. The relative temperature offset between two MTLs is thought to be a fixed value, which depends mostly on their own nature, not changing from site to site. After penetration, how the recorded temperature changes with time depends on the friction heat amount produced by penetration, if the temperature raised by friction heating is higher than ambient temperature, the temperature will drop slowly to the ambient temperature, otherwise, the temperature will raise slowly to the ambient temperature. After in-situ temperature and pressure are corrected, the thermal conductivities will decrease about 4% to 5%. The thermal gradients for the three sites are 81,109 and 94 ℃/km respectively, and thermal conductivities are 0.979, 0.785 and 0.886 W/(m·K)respectively, and heat flow values are 79, 86 and 83 mW/m² respectively.

Key words: South China Sea, heat flow, data processing, geothermal measurement