Diamond–garnet geobarometry: The role of garnet compressibility and expansivity

Milani, Simone; Nestola, Fabrizio; Alvaro, Matteo; Pasqual, Daria; Mazzucchelli, Mattia L.; Domeneghetti, M. Chiara; Geiger, Charles A.

doi:10.1016/j.lithos.2015.03.017

Cited by 77 publications

(102 citation statements)

References 53 publications

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“…11a) and is further confirmed when our data are compared with several other data sets (e.g. The room-temperature thermal expansion coefficient ( 0,303K ) has been determined as 2.55 Â 10 À5 K À1 for K 0 = 5 (as determined by Milani et al, 2015) with a E of 500 K, and its behaviour with temperature is reported in Fig. Du et al, 2015).…”

Section: Figure 10supporting

confidence: 84%

“…The first complete experiment not devoted to calibration purposes was performed on a synthetic pure grossular garnet (Ca 3 Al 2 Si 3 O 12 ) crystal synthesized at the Bayerisches Geoinstitut in a multi-anvil apparatus as described by Milani et al (2015).…”

Section: Grossularmentioning

confidence: 99%

“…pyrope, almandine; see Milani et al (2015) for a review] is fundamental for a correct estimate of the thermoelastic properties for intermediate composition such as those typically occurring for garnet inclusions trapped in diamonds. pyrope, almandine; see Milani et al (2015) for a review] is fundamental for a correct estimate of the thermoelastic properties for intermediate composition such as those typically occurring for garnet inclusions trapped in diamonds.…”

Section: Grossularmentioning

confidence: 99%

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A new micro-furnace for in situ high-temperature single-crystal X-ray diffraction measurements

et al. 2015

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A new micro-furnace equipped with an H-shaped resistance heater has been developed to conduct in situ single-crystal X-ray diffraction experiments at high temperature. The compact design of the furnace does not restrict access to reciprocal space out to 2 = 60 . Therefore, unit-cell parameters and intensity data can be determined to a resolution of 0.71 Å with Mo radiation. The combined use of mineral phases with well characterized lattice expansion (e.g. pure Si and SiO 2 quartz) and a small-diameter (0.025 mm) K-type thermocouple allowed accurate temperature calibration from room temperature to about 1273 K and consequent evaluation of thermal gradients and stability. The new furnace design allows temperatures up to about 1273 K to be reached with a thermal stability better than AE5 K even at the highest temperatures. Measurements of the lattice thermal expansion of pure silicon (Si), pure synthetic grossular garnet (Ca 3 Al 2 Si 3 O 12 ) and quartz (SiO 2 ) are presented to demonstrate the performance of the device. Its main advantages and limitations and important considerations for using it to perform high-temperature diffraction measurements are discussed.

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Section: Figure 10supporting

confidence: 84%

Section: Grossularmentioning

confidence: 99%

Section: Grossularmentioning

confidence: 99%

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A new micro-furnace for in situ high-temperature single-crystal X-ray diffraction measurements

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“…As envisaged by Rosenfeld & Chase (), the concept of the isomeke first provides the basis for determining whether over‐ or under‐pressures are developed in inclusions. Consider a garnet inclusion trapped in a diamond at mantle conditions of 5.7 GPa and 1175 °C (Howell et al ., ; Milani et al ., ). If the diamond was exhumed along the isomeke passing through the entrapment conditions (Fig.…”

Section: Inclusion Pressuresmentioning

confidence: 97%

How large are departures from lithostatic pressure? Constraints from host–inclusion elasticity

Angel

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Mazzucchelli

et al. 2015

Journal Metamorphic Geology

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Minerals trapped as inclusions within other host minerals will develop non-lithostatic pressures during both prograde and retrograde metamorphism because of the differences between the thermo-elastic properties of the host and inclusion phases. There is only a single possible path in P-T space, the entrapment isomeke, along which no residual pressure would be developed in a host/inclusion system; non-lithostatic pressures are developed in inclusions as a result of the external pressure and temperature deviating from the isomeke that passes through the entrapment conditions. With modern equation of state and elasticity data for minerals now available it is possible to perform precise calculations of the isomekes for mineral pairs. These show that isomeke lines are not straight lines in P-T space at metamorphic conditions. We show that silicate inclusions in silicate hosts tend to have flat isomekes, with small values of dP/dT(isomeke), because of the small range of thermal expansion coefficients of silicate minerals. As a consequence, the general behaviour under decompression is for soft silicate inclusions in stiffer hosts to develop excess pressures, whereas a stiff silicate inclusion in a softer matrix will experience lower pressures than lithostatic pressure. The opposite effects occur for compression after entrapment on the prograde path. The excess pressures in inclusions, including allowance for mutual elastic relaxation of the host and inclusion, are most easily calculated by using the isomeke as a basis. Analysis of the simplest possible model of a host-inclusion system indicates that deviations from lithostatic pressure in excess of 1 GPa can be readily produced in quartz inclusions within garnets in metamorphic rocks. For softer host minerals such as feldspars the pressure deviations are smaller, because of greater elastic relaxation of the host. The maximum pressure deviation from lithostatic pressure in the host phase around the inclusion is one-third of the pressure deviation in the inclusion. Routines for performing these calculations have been added to the EosFit7c software package

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“…In order to test this anomalous behaviour a synthetic single crystal of pure hercynite, FeAl 2 O 4 , was investigated by X-ray diffraction (XRD) under high-pressure conditions and room temperature using a diamond-anvil cell up to~7.5 GPa. For the purposes of comparison the same experimental approach was used as in Nestola et al (2014) obtained are expected to be crucial in determining the correct stability field and entrapment pressure of spinels in diamonds, which are based on host and inclusion thermodynamic properties, such as the bulk modulus K T0 (see Angel et al, 2015;Milani et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Equation of state of hercynite, FeAl₂O₄, and high-pressure systematics of Mg-Fe-Cr-Al spinels

et al. 2015

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In this work a single crystal of synthetic hercynite, FeAl2O4, was investigated by X-ray diffraction up to 7.5 GPa and at room temperature, in order to determine its pressurevolume equation of state. The unit-cell volume decreases non-linearly with a reduction of 3.4% (i.e. 18.43 A ˚ 3). The pressure-volume data were fitted to a third-order Birch-Murnaghan equation of state providing the following coefficients: V0 = 542.58(3) A ˚ 3, KT0 = 193.9(1.7) GPa, K’ = 6.0(5). These results are consistent with previous investigations of Cr and Al spinels measured with the same experimental approach but the KT0 differs significantly from the experimental determination carried out more than 40 years ago by Wang and Simmons (1972) by the pulse echo overlap method. Our new results were used to redetermine\ud the FeAl2O4 (hercynite) = FeO (wustite) + Al2O3 (corundum) equilibrium in PT space and obtain geobarometric information for Cr-Al spinels found as inclusions in diamond

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Diamond–garnet geobarometry: The role of garnet compressibility and expansivity

Cited by 77 publications

References 53 publications

A new micro-furnace for in situ high-temperature single-crystal X-ray diffraction measurements

A new micro-furnace for in situ high-temperature single-crystal X-ray diffraction measurements

How large are departures from lithostatic pressure? Constraints from host–inclusion elasticity

Equation of state of hercynite, FeAl₂O₄, and high-pressure systematics of Mg-Fe-Cr-Al spinels

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Diamond–garnet geobarometry: The role of garnet compressibility and expansivity

Cited by 77 publications

References 53 publications

A new micro-furnace for in situ high-temperature single-crystal X-ray diffraction measurements

A new micro-furnace for in situ high-temperature single-crystal X-ray diffraction measurements

How large are departures from lithostatic pressure? Constraints from host–inclusion elasticity

Equation of state of hercynite, FeAl2O4, and high-pressure systematics of Mg-Fe-Cr-Al spinels

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Equation of state of hercynite, FeAl₂O₄, and high-pressure systematics of Mg-Fe-Cr-Al spinels