Heat flow and heat transfer conditions in the bottom sediments of the equatorial indian ocean

The results are reported of heat flow determinations during the 10th and 11th cruises of the “Akademik Vernadsky”. Geothermal gradients were measured by the thermograd PTG-2MTB, with two temperature sensors of 1 or 1.2 m spacing. The temperature sensors were fixed to the coring tube. The lower sensor penetrated the sediment to a depth of 2.5 m. On board determinations of thermal conductivity were made by one of two methods: the needle probe method and analysis of water content in sediments. 21 heat flow measurements ranging from 4 to 120 mWm −2 have been obtained. The heat flow values depend on the type and granulometric composition of the sediments. High values are obtained on the southern slope of the Karlsberg Ridge, in the zones where bottom sediments have been found to have the maximum content of pelitic fraction and minimum of foraminifera. Low values of heat flow are due to a long-term effect of the ascending hydrothermal flow. This is confirmed by the traces of hydrothermal activity found in the sediments.