Discovery of bridgmanite, the most abundant mineral in Earth, in a shocked meteorite

Tschauner, Oliver; Ma, Chi; Beckett, J. R.; Prescher, Clemens; Prakapenka, Vitali B.; Rossman, George R.

doi:10.1126/science.1259369

Cited by 252 publications

(197 citation statements)

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“…2b). A thin layer of bridgmanite, (Mg,Fe)SiO 3 in the perovskite structure (Tschauner et al, 2014), plus wüstite occurs between ahrensite and the melt pocket (Fig. 2c).…”

Section: Methodsmentioning

confidence: 99%

Ahrensite, γ-Fe2SiO4, a new shock-metamorphic mineral from the Tissint meteorite: Implications for the Tissint shock event on Mars

Tschauner

Beckett

et al. 2016

Geochimica et Cosmochimica Acta

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. where it forms through the transformation of the fayalite-rich rims of olivine megacrysts or Fe-rich microphenocrysts in contact with shock melt pockets. We report the first comprehensive set of crystallographic, spectroscopic, and quantitative chemical analysis of type ahrensite, and show that concentrations of ferric iron and inversion in the type material of this newly approved mineral are negligible. We also report the occurrence of nanocrystalline ringwoodite in strained olivine and establish correlations between grain size and distance from melt pockets. The ahrensite and ringwoodite crystals show no preferred orientation, consistent with random 2 nucleation and incoherent growth within a highly strained matrix of olivine. Grain sizes of ahrensite immediately adjacent to melt pockets are consistent with growth during a shock of moderate duration (1-10 ms).

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“…2b). A thin layer of bridgmanite, (Mg,Fe)SiO 3 in the perovskite structure (Tschauner et al, 2014), plus wüstite occurs between ahrensite and the melt pocket (Fig. 2c).…”

Section: Methodsmentioning

confidence: 99%

Ahrensite, γ-Fe2SiO4, a new shock-metamorphic mineral from the Tissint meteorite: Implications for the Tissint shock event on Mars

Tschauner

Beckett

et al. 2016

Geochimica et Cosmochimica Acta

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“…Bridgmanite is a magnesium silicate mineral with the CaTiO 3 -perovskite structure (Pbnm space group; Tschauner et al 2014). It is the dominant mineral in the Earth's lower mantle, playing a key role in determining the seismic velocities and density structure of the deep mantle from the 660 km discontinuity until its breakdown to the CaIrO 3 -type post-perovskite structure a few hundred kilometers above the core-mantle boundary (Murakami et al 2004 (Litasov et al 2004;Holland et al 2013).…”

Section: The Bridgmanite Solid Solutionmentioning

confidence: 99%

The elastic solid solution model for minerals at high pressures and temperatures

Myhill

2018

Contrib Mineral Petrol

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Non-ideality in mineral solid solutions affects their elastic and thermodynamic properties, their thermobaric stability, and the equilibrium phase relations in multiphase assemblages. At a given composition and state of order, non-ideality in minerals is typically modelled via excesses in Gibbs free energy which are either constant or linear with respect to pressure and temperature. This approach has been extremely successful when modelling near-ideal solutions. However, when the lattice parameters of the solution endmembers differ significantly, extrapolations of thermodynamic properties to high pressures using these models may result in significant errors. In this paper, I investigate the effect of parameterising solution models in terms of the Helmholtz free energy, treating volume (or lattice parameters) rather than pressure as an independent variable. This approach has been previously applied to models of order-disorder, but the implications for the thermodynamics and elasticity of solid solutions have not been fully explored. Solid solution models based on the Helmholtz free energy are intuitive at a microscopic level, as they automatically include the energetic contribution from elastic deformation of the endmember lattices. A chemical contribution must also be included in such models, which arises from atomic exchange within the solution. Derivations are provided for the thermodynamic properties of n-endmember solutions. Examples of the use of the elastic model are presented for the alkali halides, pyroxene, garnet, and bridgmanite solid solutions. Elastic theory provides insights into the microscopic origins of non-ideality in a range of solutions, and can make accurate predictions of excess enthalpies, entropies, and volumes as a function of volume and temperature. In solutions where experimental data are sparse or contradictory, the Helmholtz free energy approach can be used to assess the magnitude of excess properties and their variation as a function of pressure and temperature. The formulation is expected to be useful for geochemical and geophysical studies of the Earth and other planetary bodies.

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“…Olivine might also transform to ringwoodite in the subducting lithosphere [13,14]. In the lower mantle (>660 km), ringwoodite decomposes to (Mg,Fe)SiO 3 -perovskite (named bridgmanite) and (Mg,Fe)O-periclase [15][16][17][18][19][20]. Natural ringwoodite was first discovered in the Tenham L6 chondrite [21], and so far it was identified only in shocked meteorites, such as ordinary chondrites, carbonaceous chondrites, lunar meteorites, and Martian meteorites [6,8,[22][23][24][25][26][27][28], except one terrestrial sample, as an inclusion in a tiny diamond crystal [29].…”

Section: Introductionmentioning

confidence: 99%

Shock-Induced Olivine-Ringwoodite Transformation in the Shock Vein of Chondrite GRV053584

et al. 2018

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Shock metamorphism of minerals in meteorites could help to understand the shock history of its parent body and also provide a window into the interior of the Earth. Although shock features in olivine have been well known within and adjacent to shock melt veins and shock melt pockets in meteorites, there are processes that are not yet completely understood. Ringwoodite is formed by crystallization from olivine melts or solid-state phase transformation of olivine. Typically, olivine clasts with a ringwoodite rim around an olivine core have been documented from only a handful of meteorites. Here we report results from GRV053684, a highly shocked L6 chondrite that was collected by Chinese Antarctic Research Expedition in 2006 to Antarctica. The investigations of the shock pressure history and the transformation mechanism of olivine to ringwoodite use optical microscope, electron probe microanalyzer (backscattered electron images, major element quantitative analyses, and quantitative wavelength-dispersive spectrometry elemental X-ray maps), and Raman spectrograph. Ringwoodite in the shock melt vein generally displays as Fe-rich (Fa 37-43 ) polycrystalline rims around ) olivine core and as small individual clasts embedded in shock melt vein matrix. The difference in FeO between ringwoodite rim and olivine core implies that Fe was preferentially partitioned to ringwoodite. The occurrence of maskelynite (An 17 ) indicates a shock pressure~30 GPa. The FeO and MgO diffusion indicates the transformation process of olivine to ringwoodite is a diffusion-controlled incoherent nucleation and growth. The spatial association between ringwoodite and the shock melt vein matrix suggests that high temperature plays a key role in prompting phase transformation.

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Discovery of bridgmanite, the most abundant mineral in Earth, in a shocked meteorite

Cited by 252 publications

References 64 publications

Ahrensite, γ-Fe2SiO4, a new shock-metamorphic mineral from the Tissint meteorite: Implications for the Tissint shock event on Mars

Ahrensite, γ-Fe2SiO4, a new shock-metamorphic mineral from the Tissint meteorite: Implications for the Tissint shock event on Mars

The elastic solid solution model for minerals at high pressures and temperatures

Shock-Induced Olivine-Ringwoodite Transformation in the Shock Vein of Chondrite GRV053584

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