Stability Relations of the Ferruginous Biotite, Annite

Eügster, Hans P.; Wones, David R.

doi:10.1093/petrology/3.1.82

Cited by 514 publications

(141 citation statements)

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“…A doublecapsule technique for sample and buffer assemblage containment was employed (Eugster and Wones, 1962). With this method, the volatile-free silicate glass + tetrakis-silane + H 2 O starting materials were loaded into an inner 3 mm-diameter by 4-5 mm long Pt capsule and welded shut.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…The sample-containing capsules were placed inside outer 5 mm-diameter by 10 mm Pt capsules together with the IW + H 2 O hydrogen buffer material and welded shut. As the Pt wall of the inner capsule is permeable to H 2 , the f H2 in the sample-containing, inner capsule is the same as that defined by the oxygen buffer + H 2 O assemblage in the outer capsule (e.g., Eugster and Wones, 1962). The hydrogen fugacity of the IW + H 2 O buffer was calculated from the dissociation constant and fugacity of H 2 O (using SUPCRIT92) and the oxygen fugacity defined by the IW buffer assemblage at the high pressure and temperature of the experiments (from Huebner, 1971).…”

Section: Experimental Methodsmentioning

confidence: 99%

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Solution behavior of reduced COH volatiles in silicate melts at high pressure and temperature

Mysen

Fogel

Morrill

et al. 2009

Geochimica et Cosmochimica Acta

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The solubility and solution mechanisms of reduced CAOAH volatiles in Na 2 OASiO 2 melts in equilibrium with a (H 2 + CH 4 ) fluid at the hydrogen fugacity defined by the iron-wü stite + H 2 O buffer [f H2 (IW)] have been determined as a function of pressure (1-2.5 GPa) and silicate melt polymerization (NBO/Si: nonbridging oxygen per silicon) at 1400°C. The solubility, calculated as CH 4 , increases from $0.2 wt% to $0.5 wt% in the melt NBO/Si-range $0.4 to $1.0. The solubility is not significantly pressure-dependent, probably because f H2 (IW) in the 1-2.5 GPa range does not vary greatly with pressure. Carbon isotope fractionation between methane-saturated melts and (H 2 + CH 4 ) fluid varied by $14& in the NBO/Si-range of these melts. The (C..H) and (O..H) speciation in the quenched melts was determined with Raman and 1 H MAS NMR spectroscopy. The dominant (C..H)-bearing complexes are molecular methane, CH 4 , and a complex or functional group that includes entities with C"CAH bonding. Minor abundance of complexes that include SiAOACH 3 bonding is tentatively identified in some melts. There is no spectroscopic evidence for SiAC or SiACH 3 . Raman spectra indicate silicate melt depolymerization (increasing NBO/Si). The [CH 4 /C"CAH] melt abundance ratio is positively correlated with NBO/Si, which is interpreted to suggest that the (C"CAH)-containing structural entity is bonded to the silicate melt network structure via its nonbridging oxygen. The $14& carbon isotope fractionation change between fluid and melt is because of the speciation changes of carbon in the melt.

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Section: Experimental Methodsmentioning

confidence: 99%

Section: Experimental Methodsmentioning

confidence: 99%

Solution behavior of reduced COH volatiles in silicate melts at high pressure and temperature

Mysen

Fogel

Morrill

et al. 2009

Geochimica et Cosmochimica Acta

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“…This is clearly the most important factor in producing larger spinels than those found in the biotites that were reacted experimentally at 800 ~ and quenched before significant grain growth could occur. biotite under pyrometamorphic conditions takes place by the reaction: Fe-Al-biotite = Mg-Al-biotite + magnetite + hercynitic spinel + K-feldspar or melt + vapour as predicted by the experimental data of Eugster and Wones (1962) and Rutherford (1973). The reaction takes place by a topotactic mechanism with the orientations of the product phases controlled by the crystallography of the reacting biotite.…”

Section: Estimates Of Reaction Timementioning

confidence: 99%

“…The effect of pressure on the position of the equilibrium breakdown curve (and hence the estimated degree of reaction overstepping) is likely to be of relative importance in dehydration reactions of this kind because of the curvature of the reaction boundary towards the pressure axis with increasing temperature. In the case of biotite the experimental data of Eugster and Wones (1962) for the dehydration of the iron end-member, annite, show that the reaction at 1 kbar proceeds at a temperature 40 ~ higher than at 0.5 kbar. However, in the case discussed here, where the overstepping temperature AT is around 250 ~ this may not have a very significant effect.…”

Section: Reaction Progress and Comparison With Experimental Kinetic Datamentioning

confidence: 99%

A natural example of the disequilibrium breakdown of biotite at high temperature: TEM observations and comparison with experimental kinetic data

Brearley

1987

Mineral. mag.

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Transmission electron microscopy has been used to investigate the mechanism of natural biotite breakdown under pyrometamorphic disequilibrium conditions. Biotite in a xenolith of pelitic gneiss collected from a Tertiary dolerite sill, Isle of Mull, Scotland, shows evidence of an incipient reaction, characterised by a darkening in colour and the appearance of areas of fine-grained reaction products. TEM and analytical electron microscope data show that the reaction can be described as:Fe-A1 biotite --* Mg-A1 biotite + magnetite + hercynitic spinel + K-feldspar/melt + vapour. The orientations of the product phase are controlled by the crystallography of the reacting biotite, demonstrating that the transformation proceeds by a topotactic mechanism. An empirical method, based on the Mg/(Fe 2+ + Fe 3 +) ratios of coexisting spinel and biotite from experimental data, is used to deduce that the reaction occurred above ~ 770 ~ A comparison of the natural reaction microstructures with those produced experimentally suggest that the xenolith was probably above 800 ~ for less than 48 hours and cooled to temperatures of 770 ~ after ~ 150-200 hours. K E Y W O R D S :transmission electron microscopy, biotite, pyrometamorphism.

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“…They are loaded with a burden consisting of natural iron ores (commonly banded iron formations), de-volatised coal, and sinter and pellet materials that are industrially preenriched in iron silicates. By controlling oxygen fugacity and temperature in the belly of a blast furnace, hot iron metal is segregated from iron ore, sinter and pellets at high-temperature conditions, and oxygen fugacities close to the iron-wuestite (IW) buffer (Eugster & Wones, 1962). Kempl et al (2013b) obtained coexisting metal and silicate samples produced in a blast furnace at Tatasteel IJmuiden, the Netherlands.…”

Section: High-pressure Experimental Methodsmentioning

confidence: 99%

Silicon stable isotope fractionation between metal and silicate at high-pressure, high-temperature conditions as a tracer of planetary core formation

Kempl

Vroon

Wagt

et al. 2016

Netherlands Journal of Geosciences

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The largest differentiation event in Earth and other terrestrial planets was the high-pressure, high-temperature process of metal core segregation from a silicate mantle. The abundant element silicon (Si) can be partially sequestered into the metallic core during metal-silicate differentiation, depending on pressure, temperature and planetary oxidation state. Knowledge of the Si content of a planet's core can constrain the conditions of core formation, but in the absence of direct samples from planetary cores, quantifying core Si content is challenging. One relatively new tool to study core formation in terrestrial planets is based on combining measurements of the Si stable isotopic composition of planetary crust and mantle samples with measurements of the Si stable isotope fractionation between metal and silicate at high-temperature and high-pressure conditions. In this study we present the results of a small set of high-pressure, high-temperature (HPT) experiments and combine these with a review of literature data to investigate how the Si isotope fractionation behaviour between metal and silicate varies as a function specifically of experimental run time and temperature. We show that although there is no debate about the sign of fractionation, absolute values for Si isotope fractionation between metal and silicate are difficult to constrain because the experimental database remains incomplete, and because Si isotopic measurements of metals in particular suffer from the absence of a true inter-laboratory comparison. We conclude that in order to derive accurate quantitative estimates of the Si content of the core of the Earth or other planets a wide range of additional experiments will be required.

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Stability Relations of the Ferruginous Biotite, Annite

Cited by 514 publications

References 0 publications

Solution behavior of reduced COH volatiles in silicate melts at high pressure and temperature

Solution behavior of reduced COH volatiles in silicate melts at high pressure and temperature

A natural example of the disequilibrium breakdown of biotite at high temperature: TEM observations and comparison with experimental kinetic data

Silicon stable isotope fractionation between metal and silicate at high-pressure, high-temperature conditions as a tracer of planetary core formation

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