Thermal equation of state of lawsonite up to 10 GPa and 973 K

Abstract

Thermal equation of state (EoS) of synthetic lawsonite [CaAl 2 Si 2 O 7 (OH) 2 ·H 2 O] has been established using insitu X-ray diffraction methods under high pressure and high temperature. Sodium chloride NaCl was used as the pressure standard in the experiments. The unit-cell volumes were measured up to 10 GPa and 973 K after the deviatric stress was released at high temperature. The P-V-T dataset was analyzed using a Birch-Murnaghan equation of state, yielding the room pressure volume V 0 = 674.2(2) Å 3 and the isothermal bulk modulus at room temperature K 0 = 129(2) GPa (K′ set to 4). These values are comparable with the previous studies. When fitting the high temperature data, a second order temperature derivative of the bulk modulus was considered. Unlike Daneil et al. (1999) who reported a minimum value of bulk modulus at~500 K, the bulk modulus decreases with increasing temperature at least up to 973 K. The dataset yields:, assuming K′ = 4. These data can be used to calculate the density and the stability of lawsonite under high pressure and high temperature conditions.

Enhanced Visibility of Subduction Slabs by the Formation of Dense Hydrous Phase A

“…Presently, direct acoustic velocity measurements on DHMS phases at mantle conditions are still scarce (e.g., Bass et al., 1991; Cai et al., 2019; Sanchez‐Valle et al., 2008). For many hydrous phases, much of our knowledge about their elastic properties at high pressure and high temperature have been limited to equation of state results derived from static compression studies (e.g., Angel et al., 2001; Cai, Inoue, & Kikegawa, 2015; Cai et al., 2018; Hilairet et al., 2006; Pawley et al., 2002; Yang et al., 2021). While these studies provide important data for the compressibility and structural behavior, they cannot address shear properties.…”

“…studies (e.g., Angel et al, 2001;Cai, Inoue, & Kikegawa, 2015;Hilairet et al, 2006;Pawley et al, 2002;Yang et al, 2021). While these studies provide important data for the compressibility and structural behavior, they cannot address shear properties.…”