P‐V‐T equation of state of stishovite up to mid‐lower mantle conditions

Abstract

[1] In situ P-V-T measurements of stishovite have been performed throughout its stability field from 17 to 54 GPa and from 300 to 1700 K, by using a sintered-diamond multianvil apparatus and synchrotron radiations. The P-V-T equation of state of stishovite was precisely determined on the basis of the Mie-Grüneisen-Debye model using both Morse-Rydberg (Vinet) and third-order Burch-Murnaghan equations for reference isotherms. The new equation of state of stishovite gives the thermoelastic properties such as density, adiabatic bulk modulus, thermal expansivity, and isobaric heat capacity without extrapolation to mid-lower mantle conditions, and these properties at zero pressures are consistent with those of previous measurements. The present equation of state yields a lower density and larger adiabatic modulus at lower mantle conditions compared to those obtained by extrapolate on using a previous equation of state determined at upper mantle conditions. Our new equation of state and thermoelastic properties for stishovite at lower mantle conditions is important for quantitatively modeling the fate of subducted silica-rich rocks such as MORB and pelagic sediments, and for interpreting seismological observations.

Melting Phase Relations and Element Partitioning in MORB to Lowermost Mantle Conditions

“…The temperature profile inside the bottom thermal boundary layer was also from Tateno, Hirose, et al (). The density of unmelted MORB rock, which comprises Mg‐pv/postperovskite, Ca‐pv, silica phases, and CF phase, is calculated in a similar manner, using available equation of state data (Ricolleau et al, ; Sakai et al, ; Wang et al, ) and the mineral proportions and chemical compositions at the lowermost mantle condition, reported in Hirose et al ().…”

Deep Earth Structure: Lower Mantle and D″

“…Eos, Transactions of the American Geophysical Union 70: 49, 54-55, 58-59. Other minor phases such as poststishovite (e.g., Bolfan-Casanova et al, 2009;Lakshtanov et al, 2007;Nomura et al, 2010;Wang et al, 2012) and various carbonates (e.g., Boulard et al, 2012;Lavina et al, 2009Lavina et al, , 2010Litasov et al, 2008;Mao et al, 2011a;Oganov et al, 2006Oganov et al, , 2008 are likely to exist in the lower mantle, but constraints on their small abundances are very limited. Transport properties for the major minerals such as electrical conductivity are also being addressed (e.g., Ono et al, 2006b;Tarits and Mandéa, 2010;Velimsky, 2010).…”

Preferred orientation in experimentally deformed stishovite: implications for deformation mechanisms

“…2). In both experiments the DACs were closed and the samples were already at pressure for the first diffraction measurements; thus, we used ambient pressure volume 112.981 Å 3 for quartz (Angel et al 1997) and 46.55 Å 3 for stishovite (Wang et al 2012) when determining pressures. The isotropic size strain model was used to fit the peak widths by refining the parameters crystallite size and r.m.s.…”

“…The hydrostatic pressure was determined as a function of volume change with a Birch Murnaghan equation of state for quartz (Angel et al 1997) and for stishovite (Wang et al 2012). Volume was calculated from the cell parameters, which are determined by the hydrostatic peak position (taken at η = 54.7° from the compression direction, described in Singh et al 1998) along 2θ (Fig.…”