| Autor: |
Han, Kenan, Wang, Duojun, Zhang, Ruixin, Chen, Peng, Cai, Nao, Zhang, Rui, Cao, Yang |
| Předmět: |
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| Zdroj: |
Journal of Geophysical Research. Planets; Jun2023, Vol. 128 Issue 6, p1-16, 16p |
| Abstrakt: |
Thermal conductivity (κ) and thermal diffusivity (D) of tremolite were measured at up to 2.5 GPa and 1,373 K using the transient plane‐source method in a multi‐anvil apparatus. Thermal conductivity and thermal diffusivity of tremolite decrease monotonically before dehydration (<1,173 K) and increase significantly after dehydration. Tremolite exhibits positive pressure dependence before dehydration. Heat capacity (C) of tremolite calculated from κ and D shows a positive pressure dependence and is controlled by an almost constant thermal expansion coefficient (α) with temperature. Conductive heat transport and radiative heat transport dominate the heat transport process before dehydration, and the significant increase in thermal conductivity after dehydration is attributed to convective heat transport. A compositional model of the Venusian lithosphere composed of a basaltic crust and peridotite mantle with or without tremolite was established. The thickness of the Venusian lithosphere with or without tremolite for Venus was calculated by combining the heat flow (from 20 to 80 mW/m2) at a certain depth (from 5 to 25 km) of crust, ranging from 24.4 to 184.6 km. Plain Language Summary: Due to the high surface temperature in Venus (∼740 K), most of the water in Venus' interior may be stored in hydrous silicate minerals. Tremolite, with a water content of about 2.3 wt.%, may be a candidate for a water reservoir on Venus due to its high thermal stability. Here, we measured the thermal conductivity and thermal diffusivity of tremolite at high temperatures and pressures beyond its stability and found that heat transport mechanisms before and after dehydration are different. Based on a basaltic crust and peridotite mantle, we established a compositional model of the Venusian lithosphere compared to that of the Earth. Combining the parameters obtained from this study, we simulated the thickness of the Venusian lithosphere involving the presence or absence of tremolite using variable thermal conductivity. The temperature profile is closer to other independent estimates; our model provides new constraints on the temperature profile of Venus in the presence of hydrous minerals. Key Points: Thermal conductivity and thermal diffusivity of tremolite were measured before and after dehydration at 303–1,373 K and 0.5–2.5 GPaThermal conductivity and thermal diffusivity of tremolite decrease monotonically before dehydration and increase after dehydrationTremolite can present in the lithospheric mantle, and the thickness of the tremolite‐bearing lithosphere is estimated [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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