Heat flow over a gas hydrate deposit in the Danube paleodelta: cruise MN249, 10-20/09/2023

This work presents results from the first purposeful in situ temperature measurements in seafloor sediments above a scalable gas hydrate deposit in the deep-water Danube paleodelta. Temperatures and temperature gradients with accuracy 5 mK and sensitivity 1 mK are measured with 3 MTL loggers with clamps (Antares GmbH) welded to a gravity corer with length of 6 m, outer diameter of 130 mm and weight ~300 kg. During the cruise MN249 on board of the Romanian R/V Mare Nigrum 10-20/10/2023, the gravity corer was deployed on 23 stations with successful temperature measurements and >3 m sediments lifting on 11 stations. Temperature gradients above the gas hydrate deposit (BSR area) are in ~20–50 mK/m when the background is ~30 mK/m. Additional data needed to determine the effects from the 2 main factors formatting temperature gradients – gas hydrate masses and sedimentation rates.