Potassium chloride-bearing ice VII and ice planet dynamics

2Citations
Citations of this article
11Readers
Mendeley users who have this article in their library.

Abstract

Accurate modeling of planetary interiors requires that the pressure-volume-temperature (PVT) properties of phases present within the body be well understood. The high-pressure polymorphs of H2O have been studied extensively due to the abundance of ice phases in icy moons and, likely, vast number of extra-solar planetary bodies, with only select studies evaluating impurity-laden ices. In this study, ice formed from a 1.6mol percent KCl-bearing aqueous solution was studied up to 32.89±0.19GPa and 625K, and the incorporation of K+ and Cl- ionic impurities into the ice VII structure was documented. The compression data at 295K were fit with a third order Birch-Murnaghan equation of state and yielded a bulk modulus (KT0), its pressure derivative (KT0'), and zero pressure volume (V0) of 24.7±0.9GPa, 4.44±0.09, and 39.2±0.2Å3, respectively. The impurity-laden ice was found to be 6-8% denser than ice VII formed from pure H2O. Thermal expansion coefficients were also determined for several isothermal compression curves at elevated temperatures, and a PVT equation of state was obtained. The melting curve of ice VII with incorporated K+ and Cl- was estimated by fitting experimental data up to 10.2±0.4GPa, where melting occurred at 625K, to the Simon-Glatzel equation. The melting curve of this impurity-laden ice is systematically depressed relative to that of pure H2O by approximately 45K and 80K at 4 and 11GPa, respectively. A portion of the K+ and Cl- contained within the ice VII structure was observed to exsolve with increasing temperature. This suggests that an internal differentiating process could concentrate a K-rich phase deep within H2O-rich planets, and we speculate that this could supply an additional source of heat through the radioactive decay of 40K. Our data illustrate ice VII can incorporate significant concentrations of K+ and Cl- and increasing the possibility of deep-sourced and solute-rich plumes in moderate to large sized H2O-rich planetary bodies.

Cite

CITATION STYLE

APA

Frank, M. R., Scott, H. P., Aarestad, E., & Prakapenka, V. B. (2016). Potassium chloride-bearing ice VII and ice planet dynamics. Geochimica et Cosmochimica Acta, 174, 156–166. https://doi.org/10.1016/j.gca.2015.11.027

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free