Thermal Conductivity and Thermal Diffusivity of Talc at High Temperature and Pressure With Implications for the Thermal Structure of Subduction Zones

Abstract

The thermal conductivity (κ $\kappa $) and thermal diffusivity (D $D$) of talc have been measured over a range of temperature (298–1,373 K) and pressure (0.5–3.0 GPa) conditions using the transient plane‐source method. The results show that both the thermal conductivity and thermal diffusivity are dependent upon the prevailing temperature and pressure conditions to a certain extent. As the temperature and pressure increase, the thermal diffusivity monotonically decreases, while the thermal conductivity initially decreases between 298 and 973 K and then increases from 973 to 1,173 K. At low temperatures, phonon scattering is the dominant mechanism for heat transfer; at higher temperatures, photon radiation and dehydration become more prevalent. At temperatures greater than 1,173 K, the thermal conductivity decreases significantly due to aqueous liquid accumulation. Talc may be the cause of the high geothermal gradient in the hot subduction zone.

An introductory review of thermal structure of subduction zones: II. Numerical approach, validation, and comparison

“…extended models of subduction zone thermal structure to include anisotropic conductivity in Tohoku where seismic anisotropy is large -they found the effects of anisotropy was minimal on thermal structure. Similar modest effects of variable conductivity on the thermal structure of subduction zones compared to, say, variations in the thermal parameter, were shown byGuo et al (2022) and Morishige…”

Thermal Conductivity and Thermal Diffusivity of Tremolite at High Temperature and Pressure and Implications for the Thermal Structure of the Venusian Lithosphere

“…The temperature dependence of thermal conductivity and thermal diffusivity can be expressed by the following empirical equations (Fu et al, 2019;Guo et al, 2022;Hofmeister et al, 2014):…”

“…The convergence of series (1) for ∆T is rapid, and the approximate solution obtained when summed to n = 10 is very accurate for the current experimental conditions (Guo et al, 2022;Osako et al, 2004;C. Wang et al, 2014;Yoneda et al, 2009).…”

“…Temperature disturbance Δ T caused by impulse heating of 23.5 W input power with a duration of 50 ms is recorded by the thermocouple. The temperature variation recorded by the thermocouple can be expressed as follows (Dzhavadov, 1975; Guo et al., 2022; Osako et al., 2004): $$${\increment}T=A\sum\limits _{n=1}^{\infty }\frac{1}{{n}^{2}}\mathrm{sin}\frac{n\pi }{3}\mathrm{sin}\frac{n\pi x}{d}\mathrm{exp}\left(-{n}^{2}Bt\right)\left[\mathrm{exp}\left({n}^{2}Bt\right)-1\right]:t > {t}_{0}$$$ where t is the time (ms) ( t = 0 represents the onset of the pulse heating), x is the distance between the pulse heater and the thermocouple (mm), d is the total height of the three sample disks (mm), and t 0 is the duration of the pulse heating (ms). The quantities A and B are defined as follows: $$$A=\frac{2Wd}{{\pi }^{2}\kappa S},B=\frac{{\pi }^{2}D}{{d}^{2}}$$$ where W is the power of the impulse heating (W), κ is thermal conductivity (W m −1 K −1 ), D is thermal diffusivity (mm 2 s −1 ), and S is the area of the impulse heater (mm 2 ).…”

Thermal conductivity of aluminous garnets in Earth’s deep interior

“…Thermal conductivity, the ability to conduct heat, of minerals under relevant high P-T conditions is a key transport property to control the thermal evolution and geodynamics in Earth's interior (Xu et al 2004;Ohta et al 2012Ohta et al , 2017Hofmeister and Branlund 2015;Hsieh et al 2017Hsieh et al , 2018Hsieh et al , 2022aY. Zhang et al 2019;Guo et al 2022;Zhang et al 2022). Such crucial property of garnets, however, had only been studied at relatively low pressure and a wide range of temperature conditions, see, e.g., (Horai 1971;Slack and Oliver 1971;Osako et al 2004;Hofmeister 2006;Marquardt et al 2009;Hofmeister and Branlund 2015).…”