Natural fluid-deposited graphite; mineralogical characteristics and mechanisms of formation

Luque, Francisco; Pasteris, Jill Dill; Wopenka, B.; Rodas, M.; Barrenechea, José F.

doi:10.2475/ajs.298.6.471

Cited by 235 publications

(204 citation statements)

References 47 publications

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“…Petrogenic graphite formation commonly occurs as a result of organic matter conversion under natural heating during low-grade metamorphism, or metamorphism of carbonate-rich rocks or organic-rich sediments, or via precipitation from natural carbonbearing fluids such as those containing CO 2 , CO, and/or CH 4 (Frost et al 1989;Person et al 1996;Luque et al 1998;Duba et al 2001, Jödicke et al 2004Pucéat et al 2004). …”

Section: Discussionmentioning

confidence: 99%

Chemical composition of the graphitic black carbon fraction in riverine and marine sediments at sub-micron scales using carbon X-ray spectromicroscopy

Haberstroh¹,

Brandes

Gélinas

et al. 2006

Geochimica et Cosmochimica Acta

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Abstract. The chemical composition of the graphitic black carbon (GBC) fraction of marine organic matter was explored in several marine and freshwater sedimentary environments along the west coast of North America and the Pacific Ocean. Analysis by carbon x-ray absorption near edge structure (C-XANES) spectroscopy and scanning transmission x-ray microscopy (STXM) show the GBC-fraction of Stillaguamish River surface sediments to be dominated by more highly-ordered and impure forms of graphite, together forming about 80% of the GBC, with a smaller percent of an aliphatic carbon component. Eel River Margin surface sediments had very little highly-ordered graphite, and were instead dominated by amorphous carbon and to a lesser extent, impure graphite.However, the GBC of surface sediments from the Washington State Slope and the Mexico Margin were composed almost solely of amorphous carbon. Pre-anthropogenic, highly-oxidized deep-sea sediments from the open Equatorial Pacific Ocean contained over half their GBC in different forms of graphite as well as highly-aliphatic carbon, low aromatic/highly-acidic aliphatic carbon, low aromatic/highly aliphatic carbon, and amorphous forms of carbon. Our results clearly show the impact of graphite and amorphous C phases in the BC fraction in modern riverine sediments and nearby marine shelf deposits. The pre-anthropogenic Equatorial Pacific GBC fraction is remarkable in the existence of highly-ordered graphite.2

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Section: Discussionmentioning

confidence: 99%

Chemical composition of the graphitic black carbon fraction in riverine and marine sediments at sub-micron scales using carbon X-ray spectromicroscopy

Haberstroh¹,

Brandes

Gélinas

et al. 2006

Geochimica et Cosmochimica Acta

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“…Syngenetic graphite usually occurs as stratabound disseminated to massive concentrations. Epigenetic graphite may occur as veins (Luque et al 1998) or as overgrowths on existing metamorphic graphite grains in areas where pervasive fluid flow took place (Farquhar, Hauri & Wang, 1999;Satish-Kumar, Wada & Santosh, 2002;Ueno et al 2002). Graphitization differs from most mineral transformations occurring during diagenesis and metamorphism in that it is an irreversible process (Grew, 1974; Buseck & † Author for correspondence: jluque@geo.ucm.es Bo-Jun, 1985;Beyssac et al 2002a).…”

Section: Introductionmentioning

confidence: 99%

Significance of graphite occurrences in the Aracena Metamorphic Belt, Iberian Massif

et al. 2004

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-The significance of syngenetic and epigenetic graphite occurrences from the Variscan hightemperature/low-pressure Aracena Metamorphic Belt is discussed in the framework of the tectonothermal evolution of this southern zone of the Iberian Massif. Syngenetic graphite is associated with both low-to medium-grade metamorphic rocks (La Umbría series, Precambrian in age) and high-grade, granulite facies rocks (the Precambrian Fuente del Oro series and a Cambrian calc-silicate series). Epigenetic, fluid-deposited occurrences correspond to overgrowths on existing metamorphic graphite grains and vein-type mineralization. Two types of graphitized particles with remarkable differences in reflectance, anisotropy and size can be distinguished in the Precambrian metapelites of the La Umbría series. Large, >150 µm length, platy crystals with high reflectance and anisotropy are interpreted as detrital and are considered indirect evidence of an old orogenic cycle prior to the Cadomian Orogeny, during which metamorphism exceeded greenschist facies. The coexistence of two types of particles explains the scattering of values of the c parameter of graphite determined by XRD (c = 6.72-6.74 Å ), and the anomalously high temperatures of the DTA exothermic peak (close to 600• C) of graphite with respect to that inferred from mineral assemblages in these rocks. The presence of graphite-rich quartzites and gneisses within the Fuente del Oro series and the calc-silicate series is evidence of sedimentation under reducing conditions in a continental shelf. The characteristics of graphite reflect the high-grade metamorphic conditions attained in the southern area of the Aracena Metamorphic Belt. Pervasive flow of fluids related to a major Variscan extensional event resulted in overgrowths on the pre-existing graphite in the gneisses and quartzites of the calc-silicate series, as evidenced by the heterogeneous isotopic composition of graphite single crystals in these rocks. A later stage of graphite precipitation is represented by scarce vein-type occurrences in mafic granulites that document channelled flow of fluids.

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“…of various sources (e.g., mantle carbon, CO 2 from decarbonation reactions, CO 2 outgassed from melts etc. ; Weis et al, 1981;Mattey, 1987;Satish -Kumar et al, 2002;Binu -lal et al, 2003;Lamb and Valley, 1985;Pineau et al, 1987;Luque et al, 1992Luque et al, , 1998Luque et al, , 2009Farquhar et al, 1999). Stable isotopic composition of C is a powerful geochemical tool widely employed for interpretation of the origin/source of carbon, based on fractionation of carbon isotopes during various surface and subsurface processes.…”

Section: Introductionmentioning

confidence: 99%

Origin of graphite in glimmerite and spinellite in Achankovil Shear Zone, southern India

Rajesh

Arai

Satish-Kumar

2009

Journal of Mineralogical and Petrological Sciences

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We report occurrence and origin of graphite in glimmerite and spinellite from an unusual ultramafic complex in Achankovil Shear Zone (ACSZ) in southern India. Raman analyses of primary graphite flakes in close association with spinel and phlogopite confirm the highly crystalline nature. The carbon isotope composition ranges from -7‰ to -9.8‰ typical of mantle -derived graphite. A genetic model is proposed in which carbon was derived from a reduced juvenile mantle source linked to the genesis of volatile rich ultramafic rocks in ACSZ.

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Natural fluid-deposited graphite; mineralogical characteristics and mechanisms of formation

Cited by 235 publications

References 47 publications

Chemical composition of the graphitic black carbon fraction in riverine and marine sediments at sub-micron scales using carbon X-ray spectromicroscopy

Chemical composition of the graphitic black carbon fraction in riverine and marine sediments at sub-micron scales using carbon X-ray spectromicroscopy

Significance of graphite occurrences in the Aracena Metamorphic Belt, Iberian Massif

Origin of graphite in glimmerite and spinellite in Achankovil Shear Zone, southern India

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