Variations in isotopic composition of carbon from metamorphic rocks in northern Sweden and their geological significance

Gavelin, Sven

doi:10.1016/0016-7037(57)90041-8

Cited by 26 publications

(3 citation statements)

References 17 publications

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“…Thus the average 4513C value for ankerite and amphibole zone graphite is -9.82_+1.66%o and that for the diopside zone graphite is not significantly different at-11.21_+2.57%o. It is a common observation that graphite isotopic composition is not related to metamorphic grade [e.g., Landergren, 1954;Wickman, 1956;Gavelin, 1957;Barker and Friedman, 1969;Degens, 1969;Andreae, 1974;Weis et al, 1981;Crawford and Valley, 1990]. In rock sequences where they are related, graphite apparently equilibrated with a single phase (i.e., fluid) of dominant mass, and therefore the relationship probably simply reflects the temperature dependence of the graphite-CO2 fracrionation factor [Wada and Oana, 1975;Hoefs and Frey, 1976;Dunn and Valley, 1992].…”

Section: Graphitementioning

confidence: 99%

Carbonaceous material in metamorphosed carbonate rocks from the Waits River Formation, NE Vermont, and its effect on electrical conductivity

Léger¹,

Mathez²,

Duba³

et al. 1996

J. Geophys. Res.

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The relations among electrical conductivity and graphite content, metamorphic grade, and fluid:rock interaction are investigated for a suite of regionally metamorphosed graphitic carbonate rocks from the Waits River Formation, NE Vermont. Graphitization was complete by the lowest grade of metamorphism attained in the area (-450øC and 450 MPa). In low-grade rocks, graphite occurs as inclusions within calcite and along grain boundaries, and in medium-grade rocks, it concentrates near porphyroblasts. In neither suite does graphite form interconnected networks. Average reduced carbon abundances are 4400 and 2800 ppm for the low-and medium-grade rocks, respectively. High-grade rocks are almost void of graphite, except for one specimen. The •513C values were determined for graphite and carbonates and •5180 values were determined for the carbonates and silicate residues. There is no change in isotopic values between low-and medium-grade rocks. In contrast, highgrade rocks show marked decreases in •5•3C and •5•80 values of-4 %0 compared to low-and medium-grade rocks. Both isotopic analyses and graphite depletion in high-grade rocks were caused by influx of large quantities of magmatic water during peak metamorphism. Electrical conductivity was measured in the laboratory on representative specimens. Rocks with high carbon content (>7000 ppm) from both the low-and high-grade zones display almost an order of magnitude higher electrical conductivity than expected from their fluid content alone. Graphite does not form an interconnected network in these rocks, yet it combines with the saline fluids to significantly increase electrical conductivities. Introduction Elemental carbon is a common constituent of metamorphic rocks, but its character, distribution, and abundance are often neglected in petrologic studies. The source of most of this carbon is organic material deposited in sedimentary environments. Prograde metamorphism converts organic debris into well-ordered graphite by recrystallization and loss of hydrocarbons [e.g., French, 1964; Diessel and Offier, 1975; Hoers and Frey, 1976; Landis, 1971; Buseck and Bo-Jun, 1985; Okuyatna-Kusunose and Itaya, 1987; Wopenka and Pasteris, 1993]. Graphite is electrically conductive, so its presence as an interconnected network may greatly increase the rock's electrical conductivity [Duba and Shankland, 1982; Frost et al., 1989; Mareschal et al., 1992]. In many regions of the world, the middle and lower crust exhibits much higher electrical conductivities than the shallow crust [e.g.dance and distribution of graphite are influenced by metamorphic processes. Although graphite has been reported in many studies of metamorphic rocks, only a few have attempted to examine its microscopic distribution [e.g., Frost et al., 1989; Mareschal et al., 1992; Tingle et al., 1991; Mathez et al., 1995] and none have examined how distribution and abundance change in response to deformation and recrystallization. Accordingly, the goals of this study are to determine (1) the physical distribution of grap...

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Section: Graphitementioning

confidence: 99%

Carbonaceous material in metamorphosed carbonate rocks from the Waits River Formation, NE Vermont, and its effect on electrical conductivity

Léger¹,

Mathez²,

Duba³

et al. 1996

J. Geophys. Res.

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“…Early studies by Landergren (1955) and Gavelin (1957) came to the conclusion that metamorphism would not significantly modify the ^^C content of the organic matter in sediments. Early studies by Landergren (1955) and Gavelin (1957) came to the conclusion that metamorphism would not significantly modify the ^^C content of the organic matter in sediments.…”

Section: Consolidated Sediments and Metasedimentsmentioning

confidence: 99%

The Isotopic Composition of Reduced Organic Carbon

Deines¹

1980

The Terrestrial Environment, A

699

502

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“…Representative studies on carbonaceous OM will only be briefly considered here and the fluid inclusion work will be briefly discussed below in the "Plutonic Rocks" section. Examples of studies of carbonaceous OM in metamorphic rocks are Gavelin (1957) on northern Swedish metamorphic rocks, Barker and Friedman (1969) on Precambrian metamorphics of southwestern Colorado, U.S.A., Andreae (1974) on southern Norway metamorphics, and Hoefs and Frey (1976) on Swiss Alps metamorphics. All four studies 13 determined 5 C ratios of the carbonaceous OM in these rocks.…”

Section: Introductionmentioning

confidence: 99%

Implications of hydrocarbons in carbonaceous metamorphic and hydrothermal ore-deposit rocks as related to the hydrolytic disproportionation of organic matter

Price¹,

DeWitt²,

Desborough³

1998

Open-File Report

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Variations in isotopic composition of carbon from metamorphic rocks in northern Sweden and their geological significance

Cited by 26 publications

References 17 publications

Carbonaceous material in metamorphosed carbonate rocks from the Waits River Formation, NE Vermont, and its effect on electrical conductivity

Carbonaceous material in metamorphosed carbonate rocks from the Waits River Formation, NE Vermont, and its effect on electrical conductivity

The Isotopic Composition of Reduced Organic Carbon

Implications of hydrocarbons in carbonaceous metamorphic and hydrothermal ore-deposit rocks as related to the hydrolytic disproportionation of organic matter

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