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[1] Characteristics of thermal responses of sediment with vertical fluid movement to periodic temperature variation at the surface were examined using a one-dimensional analytical solution. The amplitude of the thermal response decays exponentially, and the phase is delayed linearly with increasing depth, but they depend on the direction and velocity of vertical fluid flow, thermal diffusivity of fluid-saturated sediment, and period of surface temperature variation. To examine general characteristics of the thermal response, we defined two nondimensional parameters related to thermal diffusivity of fluid-saturated sediment, vertical fluid flow velocity, period of the surface temperature variation, and specific penetration depth at which the amplitude of the thermal response decays to e À1 of that at the surface. Analysis using these nondimensional parameters shows that there are three heat transport regimes for downward flow: (1) heat transport strongly governed by advection, (2) heat transport strongly governed by conduction, and (3) transition between these regimes. For upward flow, there are also three heat transport regimes: (1) balance of heat transports by advection and conduction, (2) heat transport strongly governed by conduction, and (3) transition between these regimes. The analytical solution is used to estimate the downward fluid velocity and thermal diffusivity of sediment from temperatures measured by long-term temperature monitoring at a site of seafloor hydrothermal circulation.Citation: Goto, S., M. Yamano, and M. Kinoshita (2005), Thermal response of sediment with vertical fluid flow to periodic temperature variation at the surface,

A first-order phase transition of CsSnCl3 to a cubic perovskite phase was observed at Ttr = 379 K. The electric conductivity increased from 10−6 S cm−1 to 10−3 S cm−1 at the phase transition. The temperature dependence of the electric conductivity and the X-ray diffraction data for CsSnCl3 suggested a reconstructive nature of the phase transition. On the other hand, CH3NH3SnCl3 showed successive phase transitions at 283, 307, 331, and 463 K with increasing temperature. The highest temperature phase belongs to a cubic perovskite structure, and pyramidal SnCl3− anion exists below 465 K having distorted perovskite structures. The 119Sn NMR spectra for CH3NH3SnCl3 supported the coordination change around the Sn atom, and also suggested the onset of chloride-ion diffusion just below the phase-transition temperature to the cubic phase. The activation energy for chloride-ion diffusion was found to be 54 kJ mol−1 by analyzing the temperature dependence of 119Sn NMR T1. The electric conductivity of Cs and CH3NH3 salts, however, is governed by the semiconducting property of these compounds.

The empirical relations of the thermal properties (thermal conductivity, heat capacity, specific heat, and thermal diffusivity) to the porosity and mineral composition of clay and sandy sediments recovered in the eastern flank of the Juan de Fuca Ridge are examined using the observed thermal properties, index properties, and mineral composition of the sediments. Observed thermal conductivity-porosity relations are explained using the geometric mean model. The observed relations of heat capacity and specific heat, respectively, to porosity are given by the arithmetic mean formula. A new model for the sediment thermal diffusivity-porosity relation is proposed based on models of thermal conductivity and heat capacity. This model, expressed by the geometric mean model with a correction function for the porosity and heat capacities of grain sediment and pore-filling fluid, explains the observed thermal diffusivity-porosity relations. These thermal property models are applicable to thermal properties of other sediment lithology types and are useful as standard models for estimating the thermal properties of marine sediment.

Integrated Ocean Drilling Program Expedition 301 was preceded during 2000 and 2002 by three surveys that helped to delineate seafloor and basement relief, sediment thickness, and the nature of ridge-flank hydrothermal conditions and processes on the eastern flank of the Juan de Fuca Ridge. These surveys generated swath map, seismic, and thermal data used to select locations for primary and secondary drilling targets, building from several decades of earlier work. We show compilations and examples of data from several characteristic settings in and around the Expedition 301 work area and use these observations to evaluate sedimentation patterns and thermal conditions in basement. There remain important unanswered questions in this area concerning fluid circulation within the upper oceanic crust, the magnitude of lithospheric heat input, the quantitative significance of advective heat loss from the crust, and relations between basement relief, sedimentation, and sediment alteration. These questions may be resolved through collection of a modest amount of additional data focusing on a few critical locations.