Measurement of strains in zircon inclusions by Raman spectroscopy

Stangarone, Claudia; Angel, Ross J.; Prencipe, Mauro; Campomenosi, Nicola; Mihailova, Boriana; Alvaro, Matteo

doi:10.1127/ejm/2019/0031-2851

Cited by 32 publications

(32 citation statements)

References 33 publications

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“…It is silent in the zircon phase ( B 1u mode in I4 1 ∕amd ) and becomes Raman-active above p c ( A 1 mode in I42d ). Moreover, the DFT simulations reveal that due to the pressure-enhanced lattice-dynamics instability, two Raman-active hard modes of zircon, E g near 202 cm −1 and B 2g near 265 cm −1 , soften when approaching p c , most probably because they also involve rotation/twisting of SiO 4 and ZrO 8 polyhedra about the c-axis (Stangarone et al 2019a) and can easily couple with the soft mode. The phonon mode B 2g ∼ 265 cm −1 is very weak (Kolesov et al 2001) and difficult to measure in DAC, but the theoretically predicted pressure behaviour of E g ∼ 202 cm −1 is in full accordance with the experimental data up to 10 GPa (Pina Binvignat et al 2018).…”

Section: Introductionmentioning

confidence: 99%

The pressure-induced phase transition(s) of $$\hbox {ZrSiO}_4$$: revised

et al. 2019

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The existence of a new high-pressure low-symmetry (HPLS) ZrSiO 4 phase (space group I42d), which has been predicted by density-functional-theory (DFT) calculations (Stangarone et al. in Am Mineral, 2019b), is experimentally confirmed by in situ high-pressure Raman spectroscopic analysis up to 25.3 GPa. The new ZrSiO 4 polymorph is developed from zircon via a softmode-driven displacive phase transition. The Cochran-law-type pressure dependency of the soft-mode wavenumber reveals a zircon-to-HPLS critical pressure p c = 20.98 ± 0.02 GPa. The increase in the phonon compressibilities of the zircon hard mode near 202 cm −1 at p > p r = 10.0 GPa as well as of the reidite hard mode near 349 cm −1 at p < p r marks the pressure above which zircon becomes thermodynamically metastable with respect to reidite; the experimentally determined value of p r is in good accordance with the equilibrium zircon-reidite transition pressure derived from DFT simulations. However, at room temperature, there is not enough driving force to rebuild the atomic linkages and the reconstructive transition to reidite happens ∼ 1.4 GPa above p c , indicating that at room temperature, the HPLS phase is a structural bridge between zircon and reidite. The pressure dependencies of the phonon modes in the range 350-460 cm −1 reveal that the reconstructive phase transition in the ZrSiO 4 system is triggered by energy resonance and admixture of hard modes from the parent and resultant phase.

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Section: Introductionmentioning

confidence: 99%

The pressure-induced phase transition(s) of $$\hbox {ZrSiO}_4$$: revised

et al. 2019

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“…There are other precise, minor element geothermometers applied to estimate metamorphic temperature including the Ti-in-quartz geothermometer [8,9], Zr-in-rutile geothermometer [10][11][12][13][14], and the Ti-in-zircon thermometer [12,15], etc. In recent years, based on the physical properties of the minerals, Raman-spectra geobarometers have also been developed [16][17][18][19][20][21][22][23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Original Calibration of a Garnet Geobarometer in Metapelite

2019

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In many metapelitic assemblages, plagioclase is either CaO-deficient or even absent. In such cases, all the widely applied, well-calibrated plagioclase-related geobarometers lose their usage. Fortunately, it has been found that a net-transfer reaction including intracrystalline Fe2+–Ca2+ exchange in garnet is pressure-sensitive, therefore, a garnet geobarometer can be empirically calibrated under pressure–temperature (P–T) conditions of 430~895 °C and 1~15 kbar. The chemical composition range of the calibrant garnet is XCa = 0.02~0.29 and XFe = 0.42~0.91, and covers the majority of garnet in metapelite. The total error of this geobarometer was estimated to be within ±1.3 kbar. The application of this garnet geobarometer to metamorphic terranes certifies its applicability, and this geobarometer can play a unique role, especially when plagioclase is absent or CaO-deficient. Metamorphic P–T conditions can be simultaneously determined by the garnet–biotite pair through the application of the present garnet geobarometer in combination with a well-calibrated garnet-biotite geothermometer.

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“…Figure 4 illustrates one way in which the anisotropy of the thermal pressure of a material may be evaluated, directly from the thermal expansion and compressibility tensors measured at room conditions. Figure 4a shows lines of constant a (=b) and c cell parameters calculated from the well-constrained elastic properties of zircon at room conditions [19,20]. These two lines deviate significantly from the isochor, with the consequence that there are significant linear strains along isochors (Figure 4b).…”

Section: The Consequences Of Anisotropic Pthmentioning

confidence: 99%

“…Because phonon-mode frequencies change linearly with small strains [21][22][23][24][25], this implies that the phonon-mode frequencies of materials with anisotropic thermal pressure change along the isochors, in violation of the assumptions of the QHA. Whether the resulting strains along the isochors are sufficiently large to constitute a significant violation of the QHA and invalidate the MGD EoS depends on the magnitudes of the components of the phonon-mode Grüneisen tensors which relate the phonon frequencies to the strains [19,22,23,25]. One direct test is to compare the measured changes in the phonon-mode frequencies (e.g., the frequencies of Raman bands) with pressure and with temperature.…”

Section: The Consequences Of Anisotropic Pthmentioning

confidence: 99%

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Limits to the Validity of Thermal-Pressure Equations of State

2019

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Thermal-pressure Equations of State (EoS) such as the Mie-Grüneisen-Debye (MGD) model depend on several assumptions, including the quasi-harmonic approximation (QHA) and a simplified phonon density of states. We show how the QHA is violated by materials exhibiting anisotropic thermal pressure. We also show that at pressures lower than those of the isochor of the reference volume, the static pressure may become sufficiently negative to make the compressional part of the EoS invalid. This limit is sensitive to the combined effects of the EoS parameters K’0, q and the Grüneisen parameter γ0. Large values of q, which correspond to a rapid decrease in phonon mode frequencies with increasing volume, can also lead to the bulk modulus becoming zero at high pressures and temperatures that are not particularly extreme for planetary geotherms. The MGD EoS therefore has an extremely limited P and T regime over which it is both valid and has physically-meaningful properties. Outside of this range, additional terms should be included in the thermal pressure that represents the physical properties of the solid. Or, alternatively, ‘isothermal’ EoS in which the temperature variation of the elastic properties is explicitly modeled without reference to a physical model can be used.

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Measurement of strains in zircon inclusions by Raman spectroscopy

Cited by 32 publications

References 33 publications

The pressure-induced phase transition(s) of $$\hbox {ZrSiO}_4$$: revised

The pressure-induced phase transition(s) of $$\hbox {ZrSiO}_4$$: revised

Original Calibration of a Garnet Geobarometer in Metapelite

Limits to the Validity of Thermal-Pressure Equations of State

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