Equilibria in the system Fe-C-O; Part I, Siderite-magnetite-carbon-vapor equilibrium from 500 to 10,000 bars

Weidner, J. R.

doi:10.2475/ajs.272.8.735

Cited by 25 publications

(17 citation statements)

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“…This DH f 298 ðFeCO 3 Þ fits the experiments results of Koziol (2004) at T > 500°C, and passes among French's (1971) locations of the equilibrium. This DH f 298 ðFeCO 3 Þ is also consistent with experimental locations of equilibrium [2] by Weidner (1972) and French (1971), Fig. 2, and confirm that the more negative value for DH f 298 ðFeCO 3 Þ is appropriate for high T.…”

Section: Enthalpysupporting

confidence: 89%

“…2, 500°C) was in a graphite capsule, and so was forced to graphite-saturation; it lies on the calculated location of reaction [2]. On the other hand, Weidner's (1972) experiments at P 6 1 kbar are consistent with equilibrium 3 siderite…”

Section: Enthalpymentioning

confidence: 80%

“…2). Most of Weidner's (1972) experiments suggest equilibration at lower pressure than the extrapolation of equilibrium curve at T > 600°C (solid line, Fig. 2), with a distinct change in slope at $600°C (in Fig.…”

Section: Enthalpymentioning

confidence: 91%

“…2, from solid line at high T to dotted line below 600°C). Weidner (1972) suggested that this apparent change in slope represents a phase transition in siderite, but this seems unlikely as the location of equilibrium [1] gives no sign of such a phase transition (Fig. 1).…”

Section: Enthalpymentioning

confidence: 97%

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Chemical composition of magnetite in Martian meteorite ALH 84001: Revised appraisal from thermochemistry of phases in Fe–Mg–C–O

Treiman

Essene

2011

Geochimica et Cosmochimica Acta

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Section: Enthalpysupporting

confidence: 89%

Section: Enthalpymentioning

confidence: 80%

Section: Enthalpymentioning

confidence: 91%

Section: Enthalpymentioning

confidence: 97%

See 2 more Smart Citations

Chemical composition of magnetite in Martian meteorite ALH 84001: Revised appraisal from thermochemistry of phases in Fe–Mg–C–O

Treiman

Essene

2011

Geochimica et Cosmochimica Acta

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“…10, reproduced with kind permission from Koziol 2001) over a range of pressure, temperature and oxygen fugacities (French 1971(French , 1965Koziol 2004Koziol , 2000Weidner 1972). The stability field for siderite is small in temperature/fO 2 space compared to that for magnetite and graphite.…”

Section: Macromolecular Carbon (Mmc) and Magnetitementioning

confidence: 99%

Comprehensive imaging and Raman spectroscopy of carbonate globules from Martian meteorite ALH 84001 and a terrestrial analogue from Svalbard

Steele¹,

Fries

Amundsen

et al. 2007

Meteorit & Planetary Scien

101

119

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Abstract-We report a comprehensive imaging study including confocal microRaman spectroscopy, scanning electron microscopy (SEM), and 3-D extended focal imaging light microscopy of carbonate globules throughout a depth profile of the Martian meteorite Allan Hills (ALH) 84001 and similar objects in mantle peridotite xenoliths from the Bockfjorden volcanic complex (BVC), Svalbard. Carbonate and iron oxide zoning in ALH 84001 is similar to that seen in BVC globules. Hematite appears to be present in all ALH 84001 carbonate-bearing assemblages except within a magnesite outer rim found in some globules. Macromolecular carbon (MMC) was found in intimate association with magnetite in both ALH 84001 and BVC carbonates. The MMC synthesis mechanism appears similar to established reactions within the Fe-C-O system. By inference to a terrestrial analogue of mantle origin (BVC), these results appear to represent the first measurements of the products of an abiotic MMC synthesis mechanism in Martian samples. Furthermore, the ubiquitous but heterogeneous distribution of hematite throughout carbonate globules in ALH 84001 may be partly responsible for some of the wide range in measured oxygen isotopes reported in previous studies. Using BVC carbonates as a suitable analogue, we postulate that a low temperature hydrothermal model of ALH 84001 globule formation is most likely, although alteration (decarbonation) of a subset of globules possibly occurred during a later impact event.

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Phase Diagrams of Carbonate Materials at High Pressures, with Implications for Melting and Carbon Cycling in the Deep Earth

Litasov

Shatskiy

Podborodnikov

et al. 2020

Geophysical Monograph Series

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In this chapter, we review phase diagrams of alkali and alkaline earth carbonates at high pressures, particularly simple, binary, and ternary systems, which were recently constrained at pressures of 3 and 6 GPa. These studies revealed a number of new alkali-alkaline earth double carbonates. Major transformations of high-pressure carbonates, including changes in carbon coordination, spin transition, and valence state in Fe-bearing carbonates up to the lower mantle levels, were also discussed. We emphasize the importance of carbonate systems for understanding the low-degree partial melting of carbonated mantle rocks and explaining carbonate inclusions in diamond and other deep-seated minerals. The question of carbonate stability versus the presumably reduced nature of the deep Earth's mantle provides significant impact on the further study of material transport and deep volatile cycle through the history of our planet.

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Equilibria in the system Fe-C-O; Part I, Siderite-magnetite-carbon-vapor equilibrium from 500 to 10,000 bars

Cited by 25 publications

References 0 publications

Chemical composition of magnetite in Martian meteorite ALH 84001: Revised appraisal from thermochemistry of phases in Fe–Mg–C–O

Chemical composition of magnetite in Martian meteorite ALH 84001: Revised appraisal from thermochemistry of phases in Fe–Mg–C–O

Comprehensive imaging and Raman spectroscopy of carbonate globules from Martian meteorite ALH 84001 and a terrestrial analogue from Svalbard

Phase Diagrams of Carbonate Materials at High Pressures, with Implications for Melting and Carbon Cycling in the Deep Earth

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