Inversion of needle‐probe data for sediment thermal properties of the eastern flank of the Juan de Fuca Ridge

Abstract

[1] An estimation method is introduced for measuring thermal conductivity, thermal diffusivity, and heat capacity of sediment from temperatures using a needle probe. This method is based on the continuous cylindrical heat-source model. Thermal conductivity is estimated from needle-probe temperature data using asymptotic approximation of the model. Heat capacity is then inverted from early time temperature data using a complete form of the model. Finally, thermal diffusivity is calculated from the estimated thermal conductivity and heat capacity. Numerical experiments with synthetic temperature data indicate that the estimation error of the sediment's heat capacity is $12%. The error of thermal diffusivity is thought to be greater than that of heat capacity. We apply the method to needle-probe temperature data obtained during Integrated Ocean Drilling Program Expedition 301 carried out on the eastern flank of the Juan de Fuca Ridge and estimate the sediments' thermal properties. The results indicate that thermal properties of sediments are strongly dependent on lithology and porosity. Examination results of the relations of heat capacity and thermal diffusivity to thermal conductivity show that these relations depend on the amount of quartz. The empirical formulas for these relations are provided, and they differ from those which are commonly used in thermal conductivity reduction schemes.

Physical and thermal properties of mud-dominant sediment from the Joetsu Basin in the eastern margin of the Japan Sea

“…In contrast, Goto and Matsubayashi (2008) proposed the following empirical formulae for the relationships among the thermal properties of the mud-dominant sediment on the eastern flank of the Juan de Fuca Ridge and showed that they provided a better fit to the data than the formulae of Hyndman et al (1979): (18 ⋅K . Figure 7a, b show plots of thermal diffusivity against thermal conductivity, and of heat capacity against thermal conductivity, respectively, of mud-dominant sediment for the Joetsu Basin in this study and for the Juan de Fuca Ridge (Goto and Matsubayashi 2008).…”

“…Several empirical formulae for relationships between two physical properties of marine sediment have been proposed: sound velocity and density (Hamilton 1978), sound velocity and thermal conductivity (Horai 1982), and thermal conductivity and other thermal properties (Von Herzen and Maxwell 1959;Hyndman et al 1979;Goto and Matsubayashi 2008). Empirical formulae for relationships between thermal properties and the porosity and volume fraction of constituent minerals for marine sediments have also been investigated (Kinoshita 1994;Villinger et al 1994;Goto and Matsubayashi 2009).…”

“…The mineralogy-based grain thermal conductivity and diffusivity values for mud-dominant sediment are close to the measurement-based ones for sandy sediment in the Juan de Fuca Ridge (Table 3). Goto and Matsubayashi (2009) suggested that either the mud-dominant sediment at Site 1026 contains a higher amount of quartz than that at Site U1301, or some sediment samples categorized as "mud" during the ODP Leg 168 contained sediments categorized as "mixed" lithology, composed of clay and very fine-grained sandy turbidite, during the IODP Expedition 301 (Goto and Matsubayashi 2008).…”

“…Applying the same method, Tanikawa et al (2016) determined these three properties for core samples taken from the sedimentary basin off Shimokita, Japan. Empirical formulae connecting heat capacity and thermal diffusivity to thermal conductivity for marine sediment were developed to infer heat capacity and thermal diffusivity from existing thermal conductivity data for the sediment (Von Herzen and Maxwell 1959;Hyndman et al 1979;Goto and Matsubayashi 2008). Goto and Matsubayashi (2009) investigated the relationship of thermal properties (heat capacity, specific heat, and thermal diffusivity) with the volume fractions of the component minerals of the marine sediment recovered from the eastern flank of the Juan de Fuca Ridge to calculate their thermal properties.…”

“…The relationship between thermal conductivity K s , heat capacity ρ s c s (bulk density ρ s and specific heat c s ), and thermal diffusivity κ s is given by Kinoshita et al (1996) and Hamamoto et al (2005) estimated the thermal diffusivity of marine sediment near the seafloor from the thermal response of the sediment to bottom-water temperature variation. Goto and Matsubayashi (2008) developed a method for measuring thermal conductivity and heat capacity of sediment using a single-needle probe. Using this method, they estimated the thermal conductivity and heat capacity (and hence thermal diffusivity) of marine sediment recovered at the eastern flank of the Juan de Fuca Ridge.…”