Coulometric determination of carbonates in rock samples

Sixta, V.

doi:10.1007/bf00561164

Cited by 13 publications

(9 citation statements)

References 3 publications

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“…2Bt2 68 -96 cm Brown (7.5YR 5/4) sandy loam with common medium distinct reddish brown (5YR 5/4) and light brown (7.5YR 6/4) mottles; moderate medium subangular blocky structure; friable; pH 4.6. (Duursma, 1961;Römer, 1975;Sixta, 1977). Duursma (1961) and Sixta (1977) titrated the solution using a continuous coulometric technique whereas Römer (1975) titrated with NaOH using an automatic titrator reacting on the lowering of the pH as CO, is absorbed in the Ba(OH)_, pH 10.2 solution.…”

Section: Iron Content and Color After Ignitionmentioning

confidence: 99%

“…(Duursma, 1961;Römer, 1975;Sixta, 1977). Duursma (1961) and Sixta (1977) titrated the solution using a continuous coulometric technique whereas Römer (1975) titrated with NaOH using an automatic titrator reacting on the lowering of the pH as CO, is absorbed in the Ba(OH)_, pH 10.2 solution. These titrimetric methods have low detection limits and are easy to perform.…”

Section: Iron Content and Color After Ignitionmentioning

confidence: 99%

“…had been added to prevent oxidation of organic matter. Nömmik (1971) used hot, meta-phosphoric acid to remove inorganic C from soils before determining organic C. Sixta (1977) used hot H_PO. to determine carbonates in rocks and found it superior to dilute H-SO.…”

Section: 'mentioning

confidence: 99%

“…The organic C method is based on the wet combustion method of Allison (1960) while the inorganic C method is based on the H,PO. combustion of Sixta (1977). In both methods the evolved CO ?…”

Section: 'mentioning

confidence: 99%

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Podzols and Podzolization in Temperate Regions

Mokma

Buurman

1987

Soil Science

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Section: Iron Content and Color After Ignitionmentioning

confidence: 99%

Section: Iron Content and Color After Ignitionmentioning

confidence: 99%

Section: 'mentioning

confidence: 99%

Section: 'mentioning

confidence: 99%

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Podzols and Podzolization in Temperate Regions

Mokma

Buurman

1987

Soil Science

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“…Carbon was analysed with a Coulomat C analyzer at the ETH, Zurich. Samples were fused with a Li-tetraborate flux in oxygen at 1250 °C, and the amount of CO^ liberated was determined by a coulometric-alkalimetric titration technique (Sixta, 1977).…”

Section: Sampling and Analytical Procedures For Carbon Analysismentioning

confidence: 99%

Carbon Distribution in the Stiliwater Complex and Evolution of Vapor During Crystallization of Stillwater and Bushveld Magmas

Mathez

Dietrich²,

Holloway

et al. 1989

Journal of Petrology

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The occurrence and distribution of carbon in the Stillwater Complex have been investigated. In mineralized troctolite and associated rocks of olivine-bearing zone I (OB I), carbon is present as graphitic material and calcitc. The assemblage forsterite-antigorite-calcite-graphite and the petrographic relations indicate equilibration of the carbon-rich phases during serpentinization. Typical OB I troctolite contains 500-1100 ppm wt. carbon, 40-70% of which is in calcite, whereas troctolite from higher stratigraphic positions generally contains <400 ppm carbon. Due to the metamorphism, it is not possible to deduce the extent to which enrichment of carbon in the ore zone is inherited from magmatic processes. In contrast, there is good evidence for magmatic graphite in parts of the Bushveld Complex.The C-O-H-Cl system has been investigated for conditions of Stillwater and Bushveld crystallization. In alkali-poor fluids over a wide range of igneous and metamorphic conditions, the important chlorine species are HO and CH 3 C1. The addition of chlorine to a C-O-H fluid in equilibrium with graphite leads to a quantitative increase in HO + CH 3 C1 and corresponding decrease in H 2 O contents, and, when Cl/H exceeds 1, to a CO 2 + CO-rich fluid with little H 2 O. Similarly, in more reduced fluids, CH* contents arc depressed by the formation of CH 3 O.From consideration of volatile solubilities and abundances in mafic magmas and the nature of the C-O-H-O system, it is hypothesized that the first fluid to exsolve from Bushveld and Stillwater intercumulus melt was composed of a mixture of CO 2 , CO, and HO with minor amounts of sulfur species and H 2 O. A model is developed for the evolution of such a fluid with cooling. The model assumes that graphite began to precipitate from the fluid at supersolidus temperature and that the system cooled down a T-f Ol path parallel to and > 2 log units below that of the Ni-NiO oxygen buffer. Upon the appearance of graphite, the fluid evolved to a more hydrogen-rich composition by graphite precipitation and loss of oxygen to the surrounding silicate-oxide assemblage. Cooling of fluid to 25 °C below the first appearance of graphite resulted in reduction in the fluid mass by >70%, thus concentrating chlorine, sulfur and other residual species in the intercumulus fluid and melt. The model explains the presence of chlor-apatite and the enrichment of graphite in the Bushveld Critical Zone and predicts that chlor-apatite-bearing Stillwater rocks were similarly enriched in graphite during crystallization.

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A new partial substitution mechanism of CO 3 2? /CO3OH3? and SiO 4 4? for the PO 4 3? group in hydroxyapatite from the Kaiserstuhl alkaline complex (SW-Germany)

Sommerauer

Lehnert

1985

Contr. Mineral. and Petrol.

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Coulometric determination of carbonates in rock samples

Cited by 13 publications

References 3 publications

Podzols and Podzolization in Temperate Regions

Podzols and Podzolization in Temperate Regions

Carbon Distribution in the Stiliwater Complex and Evolution of Vapor During Crystallization of Stillwater and Bushveld Magmas

A new partial substitution mechanism of CO 3 2? /CO3OH3? and SiO 4 4? for the PO 4 3? group in hydroxyapatite from the Kaiserstuhl alkaline complex (SW-Germany)

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