Assessment of the reliability of elastic geobarometry with quartz inclusions

Bonazzi, Mattia; Tumiati, Simone; Thomas, Jay B.; Angel, R. J.; Alvaro, Matteo

doi:10.1016/j.lithos.2019.105201

Cited by 57 publications

(110 citation statements)

References 23 publications

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“…Figure b shows that

P_{inc}^{hyd}

determined from the hydrostatic calibrations for the 128 and 206 cm −1 Raman bands are less than

P_{inc}^{normale .t .}

and

P_{inc}^{normalv .s .}

, whereas the 464 cm −1 band gives

P_{inc}^{hyd}

values that are similar to

P_{inc}^{normale .t .}

and

P_{inc}^{normalv .s .}

because the slope of the isoshift line for the 464 cm −1 band are close to that of the isobar (see Murri et al, ), in agreement with what was proposed (Bonazzi et al, in press). In general, the

P_{inc}^{normale .t .}

and

P_{inc}^{normalv .s .}

calculations give similar

P_{inc}

values (Figure b).…”

Section: Resultssupporting

confidence: 90%

“…Further restricting the anisotropy criterion does not decrease the

P_{inc}^{normalv .s .}

P_{inc}^{normale .t .}

SEs and was considered unnecessary, thus further confirming the validity of the anisotropy criterion. In this study,

P_{inc}^{normale .t .}

and

P_{inc}^{normalv .s .}

determined are indistinguishable from one another (Figures b and b) because of the relatively low deviatoric strains if compared with the synthetic samples of Bonazzi et al (in press).…”

Section: Resultscontrasting

confidence: 46%

“…For suitable inclusions, remnant inclusion pressures (

P_{inc}

) were calculated from room temperature measurements of the 128, 206, and 464 cm −1 Raman bands of quartz inclusions in garnet using (a) hydrostatic pressure calibration (

P_{inc}^{hyd}

; Schmidt & Ziemann, ; Thomas & Spear, ), (b) volume strain calculation (

P_{inc}^{normalv .s .}

), and (c) elastic tensor calculation (

P_{inc}^{normale .t .}

; Table ; Bonazzi, Tumiati, Thomas, Angel, & Alvaro, in press; Murri et al, ).

P_{inc}^{hyd}

values calculated from the hydrostatic calibration assume that the inclusion is subject to hydrostatic (i.e.…”

Section: Thermobarometric Methodsmentioning

confidence: 99%

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Quartz‐in‐garnet and Ti‐in‐quartz thermobarometry: Methodology and first application to a quartzofeldspathic gneiss from eastern Papua New Guinea

Gonzalez

Thomas

Baldwin

et al. 2019

Journal Metamorphic Geology

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Mineral inclusions are ubiquitous in metamorphic rocks and elastic models for host‐inclusion pairs have become frequently used tools for investigating pressure–temperature (P–T) conditions of mineral entrapment. Inclusions can retain remnant pressures (Pinc) that are relatable to their entrapment P–T conditions using an isotropic elastic model and P–T–V equations of state for host and inclusion minerals. Elastic models are used to constrain P–T curves, known as isomekes, which represent the possible inclusion entrapment conditions. However, isomekes require a temperature estimate for use as a thermobarometer. Previous studies obtained temperature estimates from thermometric methods external of the host‐inclusion system. In this study, we present the first P–T estimates of quartz inclusion entrapment by integrating the quartz‐in‐garnet elastic model with titanium concentration measurements of inclusions and a Ti‐in‐quartz solubility model (QuiG‐TiQ). QuiG‐TiQ was used to determine entrapment P–T conditions of quartz inclusions in garnet from a quartzofeldspathic gneiss from Goodenough Island, part of the (ultra)high‐pressure terrane of Papua New Guinea. Raman spectroscopic measurements of the 128, 206, and 464 cm−1 bands of quartz were used to calculate inclusion pressures using hydrostatic pressure calibrations (Pinchyd), a volume strain calculation (Pincnormalv.s.), and elastic tensor calculation (Pincnormale.t.), that account for deviatoric stress. Pinchyd values calculated from the 128, 206, and 464 cm−1 bands’ hydrostatic calibrations are significantly different from one another with values of 1.8 ± 0.1, 2.0 ± 0.1, and 2.5 ± 0.1 kbar, respectively. We quantified elastic anisotropy using the 128, 206 and 464 cm−1 Raman band frequencies of quartz inclusions and stRAinMAN software (Angel, Murri, Mihailova, & Alvaro, 2019, 234:129–140). The amount of elastic anisotropy in quartz inclusions varied by ~230%. A subset of inclusions with nearly isotropic strains gives an average Pincnormalv.s. and Pincnormale.t. of 2.5 ± 0.2 and 2.6 ± 0.2 kbar, respectively. Depending on the sign and magnitude, inclusions with large anisotropic strains respectively overestimate or underestimate inclusion pressures and are significantly different (<3.8 kbar) from the inclusions that have nearly isotropic strains. Titanium concentrations were measured in quartz inclusions exposed at the surface of the garnet. The average Ti‐in‐quartz isopleth (19 ± 1 ppm [2σ]) intersects the average QuiG isomeke at 10.2 ± 0.3 kbar and 601 ± 6°C, which are interpreted as the P–T conditions of quartzofeldspathic gneiss garnet growth and entrapment of quartz inclusions. The P–T intersection point of QuiG and Ti‐in‐quartz univariant curves represents mechanical and chemical equilibrium during crystallization of garnet, quartz, and rutile. These three minerals are common in many bulk rock compositions that crystallize over a wide range of P–T conditions thus permitting application of QuiG‐TiQ to many metamorphic rocks.

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“…Figure b shows that

P_{inc}^{hyd}

determined from the hydrostatic calibrations for the 128 and 206 cm −1 Raman bands are less than

P_{inc}^{normale .t .}

and

P_{inc}^{normalv .s .}

, whereas the 464 cm −1 band gives

P_{inc}^{hyd}

values that are similar to

P_{inc}^{normale .t .}

and

P_{inc}^{normalv .s .}

because the slope of the isoshift line for the 464 cm −1 band are close to that of the isobar (see Murri et al, ), in agreement with what was proposed (Bonazzi et al, in press). In general, the

P_{inc}^{normale .t .}

and

P_{inc}^{normalv .s .}

calculations give similar

P_{inc}

values (Figure b).…”

Section: Resultssupporting

confidence: 90%

“…Further restricting the anisotropy criterion does not decrease the

P_{inc}^{normalv .s .}

P_{inc}^{normale .t .}

SEs and was considered unnecessary, thus further confirming the validity of the anisotropy criterion. In this study,

P_{inc}^{normale .t .}

and

P_{inc}^{normalv .s .}

determined are indistinguishable from one another (Figures b and b) because of the relatively low deviatoric strains if compared with the synthetic samples of Bonazzi et al (in press).…”

Section: Resultscontrasting

confidence: 46%

“…For suitable inclusions, remnant inclusion pressures (

P_{inc}

) were calculated from room temperature measurements of the 128, 206, and 464 cm −1 Raman bands of quartz inclusions in garnet using (a) hydrostatic pressure calibration (

P_{inc}^{hyd}

; Schmidt & Ziemann, ; Thomas & Spear, ), (b) volume strain calculation (

P_{inc}^{normalv .s .}

), and (c) elastic tensor calculation (

P_{inc}^{normale .t .}

; Table ; Bonazzi, Tumiati, Thomas, Angel, & Alvaro, in press; Murri et al, ).

P_{inc}^{hyd}

values calculated from the hydrostatic calibration assume that the inclusion is subject to hydrostatic (i.e.…”

Section: Thermobarometric Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Quartz‐in‐garnet and Ti‐in‐quartz thermobarometry: Methodology and first application to a quartzofeldspathic gneiss from eastern Papua New Guinea

Gonzalez

Thomas

Baldwin

et al. 2019

Journal Metamorphic Geology

Self Cite

View full text Add to dashboard Cite

show abstract

“…Existing models that link residual pressure and entrapment P -T conditions are based on elastic rheology and often assume an infinite host radius (Rosenfeld and Chase, 1961;Van Der Molen and Van Roermund, 1986;Guiraud and Powell, 2006;Angel et al, 2017b). Despite these simplifications, recent experimental works have been successfully performed to compare the measured residual pressure with modelled residual pressure under well-controlled P -T conditions for synthetic samples with a quartz-in-garnet system (Thomas and Spear, 2018;Bonazzi et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Post-entrapment modification of residual inclusion pressure and its implications for Raman elastic thermobarometry

2020

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Abstract. Residual pressure can be preserved in mineral inclusions, e.g. quartz-in-garnet, after exhumation due to differential expansion between inclusion and host crystals. Raman spectroscopy has been applied to infer the residual pressure and provides information on the entrapment temperature and pressure conditions. However, the amount of residual pressure relaxation cannot be directly measured. An underestimation or overestimation of residual pressure may lead to significant errors between calculated and actual entrapment pressure. This study focuses on three mechanisms responsible for the residual pressure modification: (1) viscous creep; (2) plastic yield; (3) proximity of inclusion to the thin-section surface. Criteria are provided to quantify how much of the expected residual pressure is modified due to these three mechanisms. An analytical solution is introduced to demonstrate the effect of inclusion depth on the residual pressure field when the inclusion is close to the thin-section surface. It is shown that for a quartz-in-garnet system, the distance between the thin-section surface and inclusion centre needs to be at least 3 times the inclusion radius to avoid pressure release. In terms of viscous creep, representative case studies on a quartz-in-garnet system show that viscous relaxation may occur from temperatures as low as 600–700 ∘C depending on the particular pressure–temperature (P–T) path and various garnet compositions. For quartz entrapped along the prograde P–T path and subject to viscous relaxation at peak T above 600–700 ∘C, its residual pressure after exhumation may be higher than predicted from its true entrapment conditions. Moreover, such a viscous resetting effect may introduce apparent overstepping of garnet nucleation that is not related to reaction affinity.

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“…This observation is also important for the recent development of elastic geobarometry [26,27]. The elastic anisotropy seems to be a major factor that needs to be taken into account for calculating the Ps for various geological processes, in particular when the rock has experienced high-grade metamorphism and eclogite facies are found [49][50][51].…”

Section: Resultsmentioning

confidence: 99%

Hydrogen Effect on the Sound Velocities of Upper Mantle Omphacite

et al. 2019

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Clinopyroxene (Cpx) is commonly believed to be the best structural water (hydrogen) carrier among all major upper mantle nominally anhydrous minerals (NAMs). In this study, we have measured the single-crystal elastic properties of a Cpx, a natural omphacite with~710 ppm water at ambient pressure (P) and temperature (T) conditions. Utilizing the single-crystal X-ray diffraction (XRD) and electron microprobe data, the unit cell parameters and density were determined as a = 9.603(9) Å, b = 8.774(3) Å, c = 5.250(2) Å, β = 106.76(5) o , V = 255.1(4) Å 3 , and = 3.340(6) g/cm 3 . We performed Brillouin spectroscopy experiments on four single crystals along a total of 52 different crystallographic directions. The best-fit single-crystal elastic moduli (C ij s), bulk and shear moduli were determined as: C 11 = 245(1) GPa, C 22 = 210(2) GPa, C 33 = 249.6(9) GPa, C 44 = 75.7(9) GPa, C 55 = 71.2(5) GPa, C 66 = 76(1) GPa, C 12 = 85(2) GPa, C 13 = 70(1) GPa, C 23 = 66(2) GPa, C 15 = 8.0(6) GPa, C 25 = 6(1) GPa, C 35 = 34.7(6) GPa, and C 46 = 8.7(7) GPa, K S0 = 125(3) GPa, and G 0 = 75(2) GPa, respectively. Compared with the anticipated elastic properties of an anhydrous omphacite with the same chemical composition, our results indicate that the incorporation of~710 ppm structural water has no resolvable effect on the aggregate elastic properties of omphacite, although small differences (up to~9 GPa) were observed in C 13 , C 25 , C 44 , and C 66 .

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Assessment of the reliability of elastic geobarometry with quartz inclusions

Cited by 57 publications

References 23 publications

Quartz‐in‐garnet and Ti‐in‐quartz thermobarometry: Methodology and first application to a quartzofeldspathic gneiss from eastern Papua New Guinea

Quartz‐in‐garnet and Ti‐in‐quartz thermobarometry: Methodology and first application to a quartzofeldspathic gneiss from eastern Papua New Guinea

Post-entrapment modification of residual inclusion pressure and its implications for Raman elastic thermobarometry

Hydrogen Effect on the Sound Velocities of Upper Mantle Omphacite

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