Transformation of enstatite ? diopside ? jadeite pyroxenes to garnet

Gasparik, Tibor

doi:10.1007/bf00371083

Cited by 187 publications

(128 citation statements)

References 27 publications

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“…1470°C, which is 30°C less than that measured with the thermocouple. This is within uncertainty of the experimental data in Gasparik (1989), which was 30°C. Therefore, we regard the temperature measured with the thermocouple to be the temperature inside the capsule.…”

Section: Appendix 1: Calculation Of the Melting Phase Relationssupporting

confidence: 62%

Major element composition of an Early Enriched Reservoir: constraints from 142Nd/144Nd isotope systematics in the early Earth and high-pressure melting experiments of a primitive peridotite

Kondo

Yoshino

Matsukage

et al. 2016

Prog. in Earth and Planet. Sci.

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The Accessible Silicate Earth (ASE) has a higher 142 Nd reservoir is believed to have been derived from a melt in the early Earth and is called the Early Enriched Reservoir (EER). Although the major element composition of the EER is crucial for estimating its chemical and physical properties (e.g., density) and is also essential for understanding the origin and fate of the EER, which are both major factors that determine the present composition of the Earth, it has not yet been robustly established. In order to determine the major element composition of the EER, we estimated the age and pressuretemperature conditions to form the EER that would best explain its Nd isotopic characteristics, based on Sm-Nd partitioning and its dependence on pressure, temperature, and melting phase relations. Our estimate indicates that the EER formed within 33.5 Myr of Solar System formation and at near-solidus temperatures and shallow uppermantle pressures. We then performed high-pressure melting experiments on primitive peridotite to determine the major element composition of the EER at estimated temperature at 7 GPa and calculated the density of the EER. The result of our experiments indicates that the near-solidus melt is iron-rich komatiite. The estimated density of the near-solidus melt is lower than that of the primitive peridotite, suggesting that the EER melt would have ascended in the mantle to form an early crust. Given that high mantle potential temperatures are assumed to have existed in the Hadean, it follows that the EER melt was generated at high pressure and, therefore, its composition would have been picritic to komatiitic. As the formation age of the EER estimated in our study precedes the last giant, lunar-forming impact, the picritic to komatiitic crust (EER) would most likely have been ejected from the Earth by the last giant impact or preceding impacts. Thus, the EER has been lost, leaving the Earth more depleted than its original composition.

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Section: Appendix 1: Calculation Of the Melting Phase Relationssupporting

confidence: 62%

Major element composition of an Early Enriched Reservoir: constraints from 142Nd/144Nd isotope systematics in the early Earth and high-pressure melting experiments of a primitive peridotite

Kondo

Yoshino

Matsukage

et al. 2016

Prog. in Earth and Planet. Sci.

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“…The solubility of calcium in clinopyroxene coexisting with orthopyroxene is a strong function of temperature, and it can be used to record thermal gradients within sample assemblies [Gasparik, 1989]. The most definitive characterization of thermal gradients was produced from multithermocouple experiments performed in the multianvil apparatus.…”

Section: Methodsmentioning

confidence: 99%

Divalent cation diffusion in Mg₂SiO₄ spinel (ringwoodite), β phase (wadsleyite), and olivine: Implications for the electrical conductivity of the mantle

Farber¹,

Williams²,

Ryerson³

2000

J. Geophys. Res.

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respectively. Our results demonstrate that extreme differences in transport properties are expected to occur across the 400 km discontinuity. A model for electrical conductivity in the upper mantle involving two mechanisms for electrical conduction, with one mechanism being associated with a hydrogen or defect-related conduction process and the other involving a straightforward application of the Nernst-Einstein equation to our cationic diffusion data, reproduces geomagnetic sounding results for the upper mantle and shallow transition zone. This modeling yields an order of magnitude increase in electrical conductivity across the 400 km discontinuity, with little or no change in conductivity occurring near 520 km depth. Our modeling suggests that divalent cation diffusion is the dominant mechanism of charge transport between 400 and 670 km depth and that the high-pressure olivine polymorphs dominate the electrical behavior of the deep upper mantle. Comparison between field-based deep-mantle conductivity profiles derived from magnetotelluric studies and extrapolation of our model suggests that a discontinuity in electrical transport properties exists at the base of the transition zone as well. Similarly, given the dramatic differences in chemical diffusion between different polymorphs of olivine, it is possible that other transport property-mediated processes, such as viscous flow, could dramatically change across the 400 and 670 km discontinuities; such changes are less likely to occur at 520 km depth. IntroductionThe chemical transport properties of the dominant phases of the Earth's mantle are vital in determining the rate of viscous flow, the magnitude of electrical conductivity, and the dimensions and lifespans of geochemical heterogeneities within this region of the planet. In turn, the contribution of mantle convection rates to plate motions, the propagation of the geomagnetic field through the mantle to the surface of the planet, and the petrogenetic properties of the upper mantle are to some

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“…The multianvil experiment was performed at GFZ Potsdam with a 10/5 assembly, which was calibrated using the following transitions: coesite-stishovite [24], α-β Mg 2 SiO 4 [25], β-γ Mg 2 SiO 4 [26], and enstatite-β-Mg 2 SiO 4 -stishovite [27]. In all three experiments, stepped graphite heaters were applied and temperatures were measured with type-C thermocouples, with emf's uncorrected for pressure.…”

Section: Methodsmentioning

confidence: 99%

Ferroelectric soft mode of polarZnTiO3investigated by Raman spectroscopy at high pressure

et al. 2015

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We explore the vibrational behavior and stability of ferroelectric ZnTiO 3 under high pressure by Raman spectroscopy and second-harmonic-generation (SHG) measurements. Ab initio lattice-dynamics calculations have been employed to solve a controversy concerning the phonon-dispersion relations of ZnTiO 3 and to carry out an assignment of the Raman modes. A ferroelectric to paraelectric phase transition has been observed both by Raman spectroscopy and SHG at 20.8 GPa. Contrary to LiNbO 3 , the ferroelectric soft mode of ZnTiO 3 has been found to be the A 1 (2) and not the A 1 (1) mode. The calculated eigenvectors show that the A 1 (2) mode of ferroelectric ZnTiO 3 is an antiphase vibration of the Ti atom against the oxygen framework, similar to the soft modes observed in ferroelectric perovskites. The SHG signal of ZnTiO 3 has been found to be independent of the grain size below the phase transition, indicating that ZnTiO 3 is a phase-matchable compound.

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Transformation of enstatite ? diopside ? jadeite pyroxenes to garnet

Cited by 187 publications

References 27 publications

Major element composition of an Early Enriched Reservoir: constraints from 142Nd/144Nd isotope systematics in the early Earth and high-pressure melting experiments of a primitive peridotite

Major element composition of an Early Enriched Reservoir: constraints from 142Nd/144Nd isotope systematics in the early Earth and high-pressure melting experiments of a primitive peridotite

Divalent cation diffusion in Mg₂SiO₄ spinel (ringwoodite), β phase (wadsleyite), and olivine: Implications for the electrical conductivity of the mantle

Ferroelectric soft mode of polarZnTiO3investigated by Raman spectroscopy at high pressure

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Transformation of enstatite ? diopside ? jadeite pyroxenes to garnet

Cited by 187 publications

References 27 publications

Major element composition of an Early Enriched Reservoir: constraints from 142Nd/144Nd isotope systematics in the early Earth and high-pressure melting experiments of a primitive peridotite

Major element composition of an Early Enriched Reservoir: constraints from 142Nd/144Nd isotope systematics in the early Earth and high-pressure melting experiments of a primitive peridotite

Divalent cation diffusion in Mg2SiO4 spinel (ringwoodite), β phase (wadsleyite), and olivine: Implications for the electrical conductivity of the mantle

Ferroelectric soft mode of polarZnTiO3investigated by Raman spectroscopy at high pressure

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Divalent cation diffusion in Mg₂SiO₄ spinel (ringwoodite), β phase (wadsleyite), and olivine: Implications for the electrical conductivity of the mantle