Temperature and Density on the Forsterite Liquid-Vapor Phase Boundary

© 2021. Lawrence Livermore National Laboratory/Security, LLC..

The physical processes during planet formation span a large range of pressures and temperatures. Giant impacts, such as the one that formed the Moon, achieve peak pressures of 100s of GPa. The peak shock states generate sufficient entropy such that subsequent decompression to low pressures intersects the liquid-vapor phase boundary. The entire shock-and-release thermodynamic path must be calculated accurately in order to predict the post-impact structures of planetary bodies. Forsterite (Mg2SiO4) is a commonly used mineral to represent the mantles of differentiated bodies in hydrocode models of planetary collisions. Here, we performed shock experiments on the Sandia Z Machine to obtain the density and temperature of the liquid branch of the liquid-vapor phase boundary of forsterite. This work is combined with previous work constraining pressure, density, temperature, and entropy of the forsterite principal Hugoniot. We find that the vapor curves in previous forsterite equation of state models used in giant impacts vary substantially from our experimental results, and we compare our results to a recently updated equation of state. We have also found that due to under-predicted entropy production on the principal Hugoniot and elevated temperatures of the liquid vapor phase boundary of these past models, past impact studies may have underestimated vapor production. Furthermore, our results provide experimental support to the idea that giant impacts can transform much of the mantles of rocky planets into supercritical fluids.

Medienart:

E-Artikel

Erscheinungsjahr:

2021

Erschienen:

2021

Enthalten in:

Zur Gesamtaufnahme - volume:126

Enthalten in:

Journal of geophysical research. Planets - 126(2021), 4 vom: 08. Apr., Seite e2020JE006745

Sprache:

Englisch

Beteiligte Personen:

Davies, E J [VerfasserIn]
Duncan, M S [VerfasserIn]
Root, S [VerfasserIn]
Kraus, R G [VerfasserIn]
Spaulding, D K [VerfasserIn]
Jacobsen, S B [VerfasserIn]
Stewart, S T [VerfasserIn]

Links:

Volltext

Themen:

Equation of state
Hugoniot
Journal Article
Melting
Shock wave
Supercritical
Vaporization

Anmerkungen:

Date Revised 02.04.2024

published: Print-Electronic

Citation Status PubMed-not-MEDLINE

doi:

10.1029/2020JE006745

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM327684321