[S24-1] Methods and instruments of experimental geothermics - application and recent evolution I

[S24-1-01] Thermal properties of mud-dominant sediment from the Joetsu Basin in the eastern margin of the Japan Sea

^○Shusaku Goto¹, Makoto Yamano², Sumito Morita¹, Toshiya Kanamatsu³, Akihiro Hachikubo⁴, Satsuki Kataoka⁵, Manabu Tanahashi⁶, Ryo Matsumoto⁶ (1.National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan, 2.The University of Tokyo, Tokyo, Japan, 3.Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan, 4.Kitami Institute of Technology, Kitami, Japan, 5.Kobe University, Kobe, Japan, 6.Meiji University, Tokyo, Japan)

Thermal properties (thermal conductivity, heat capacity, specific heat, and thermal diffusivity) of marine sediment are important parameters for estimating the flow of fluid and heat in sediment and modeling thermal structure below the seafloor. Although many thermal conductivity data on marine sediment have been accumulated, there are relatively few studies on heat capacity, specific heat, and thermal diffusivity of marine sediment. In this study, we measured thermal conductivity and heat capacity for mud-dominant sediment recovered from the Joetsu Basin in the eastern margin of the Japan Sea by applying the dual-needle probe method. We also measured physical properties (bulk density and porosity) for the mud-dominant sediment. Thermal diffusivity and specific heat of the sediment were calculated from the measured physical and thermal properties. Using the measured thermal properties of the sediment, we propose empirical formulae for the relationships between thermal diffusivity and thermal conductivity, and heat capacity and thermal conductivity for the sediment in the Joetsu Basin. These relationships are different from those for mud-dominant sediment in the eastern flank of the Juan de Fuca Ridge presented in previous work. We suggest that the differences of the relationships between these areas are derived from a difference in mineral composition, probably mainly in the amount of quartz, between the sediments in these areas. This study was financially supported by the MH21 Research Consortium for Methane Hydrate Resources in Japan.