Density of jadeite melts under high pressure and high temperature conditions

Abstract

The density of the jadeite (NaAlSi 2 O 6 ) melt has been measured up to 6.5 GPa and 2273 K using the X-ray absorption technique at beamline 13-BM-D of the Advanced Photon Source. A fit of the pressure-densitytemperature data to the high temperature Birch-Murnaghan equation of state yielded the following thermoelastic parameters: density, ρ 0 = 2.36 g/cm 3 , isothermal bulk modulus, K T0 = 21.5 ± 0.8 GPa, its pressure derivative, K 0 A = 8.9 ± 1.2, and the temperature derivative (∂K T /∂T ) P = −0.0021 ± 0.0011 GPa/K at a reference temperature T 0 = 1473 K. The densification of jadeite melt at low pressures is primarily dominated by topological changes in the structure, including a decrease in T-O-T angle and breaking and reforming of the T-O bond (T = Si 4+ , Al 3+ ). Compressibilities of jadeite, albite, diopside, phonolite and peridotite melts display a systematic trend: the K 0 -K 0 A plot of these silicate melts exhibits an inverse linear relation.

Density of NaAlSi2O6 Melt at High Pressure and Temperature Measured by In-Situ X-ray Microtomography

“…However, because the study conducted by Suzuki et al [21] was mainly devoted to viscosity measurements and only a small fraction of the paper describes the MD simulations of density for jadeite melt, not sufficient details are given to resolve the deviation in pressure effects. The densities measured by the X-ray absorption method in the study of [33], on the other hand, are significantly lower than our results and both simulation results. The reason for this discrepancy is not unclear.…”

“…The high-pressure densities determined in this study are consistent with the room-pressure density calculated from the ideal mixing model using partial molar volumes of the oxide components [54]. Figure 4 compares our results with previous studies on jadeite melt including X-ray absorption measurements from Sakamaki [33], FPMD simulations from Bajgain et al [38], and classical molecular dynamics (MD) simulations from Suzuki et al [21]. After correcting for thermal effects, our data are mostly consistent with the results from the FPMD [38] over the entire pressure range of our experiments.…”

“…The high viscosity, high reactivity, and low density of alkali-rich melts hinder the application of some of the most widely used melt density measuring techniques, such as the sink-float [1,[26][27][28][29] and shock-wave [30][31][32] techniques. Until now, the only experimental data on the density of jadeite melt at high pressures were obtained by Sakamaki [33] using the X-ray absorption method [34][35][36][37], in which the density was calculated from the X-ray absorption contrast between the sample and diamond lid using the Beer-Lambert law and the mass absorption coefficients, but his results are not in agreement with a recent first-principles molecular dynamics (FPMD) study on jadeite melt [38].…”

Gem sparkles deep: Preface of the special issue on ‘Jadeite and jadeitite’

“…The final paper of this special issue by Sakamaki (2017) reports results of in-situ density measurements of jadeite melt under high-pressure and high-temperature, up to 6.5 GPa and 2273 K. Using the result measured in a beamline of synchrotron radiation facility, he discusses the compression mechanisms of jadeite melts. …”

“…The JAMS invited two review articles on Japanese jadeitites (Tsujimori and Harlow, 2017;Nishiyama et al, 2017) and requested another four review articles (Tsujimori, 2017;Miyajima, 2017;Hirajima, 2017;Ohtani et al, 2017) from experts with JAMS membership. In addition, in response to a call for papers to the Japanese geoscience community, five research articles Goto et al, 2017;Fukuyama et al, 2017;Takahashi et al, 2017;Sakamaki, 2017) were contributed from the authors and authors' groups conducting research on jadeite and jadeitite. The eleven papers in this issue cover the fields of mineralogy, petrology, geochemistry, geochronology, mineral physics, and planetary science from different perspectives.…”