Low-density CO2-rich fluid inclusions from charnockites of southwestern Madurai Granulite Block, southern India; implications on graphite mineralization

Baiju, K. R.; Nambiar, C.G.; Jadhav, G.N.; Kagi, Hiroyuki; Satish-Kumar, M.

doi:10.1016/j.jseaes.2009.06.010

Cited by 10 publications

(6 citation statements)

References 56 publications

(63 reference statements)

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“…Thus, Farquhar and Chacko (1991) and Baiju et al (2009) reported centimetre-scale d 13 C variation in graphite along a dike margin associated with incipient charnockite as the result of mechanical mixing between original metamorphic graphite (isotopically light) and fluid-deposited graphite from isotopically heavier, magmatically-derived CO 2 -rich fluids. The conclusions of these studies therefore stress the importance of textural observations for a proper understanding of the causes of isotopic variation at any scale.…”

Section: Mixing Of Fluidsmentioning

confidence: 98%

“…Thus, Baiju et al (2009) recognized three types of fluid inclusions representing three important stages in the evolution of the granulite rocks of the Madurai Block (southern India). The earliest generation are monophase CO 2 inclusions that do not preserve the fluid densities from the peak granulite-facies metamorphism.…”

Section: C-o-h Fluids With Two Carbon Speciesmentioning

confidence: 99%

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Carbon isotopes of graphite: Implications on fluid history

Luque

Crespo-Feo

Barrenechea

et al. 2012

Geoscience Frontiers

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Stable carbon isotope geochemistry provides important information for the recognition of fundamental isotope exchange processes related to the movement of carbon in the lithosphere and permits the elaboration of models for the global carbon cycle. Carbon isotope ratios in fluid-deposited graphite are powerful tools for unravelling the ultimate origin of carbon (organic matter, mantle, or carbonates) and help to constrain the fluid history and the mechanisms involved in graphite deposition. Graphite precipitation in fluid-deposited occurrences results from CO 2 -and/or CH 4 -bearing aqueous fluids. Fluid flow can be considered as both a closed (without replenishment of the fluid) or an open system (with renewal of the fluid by successive fluid batches). In closed systems, carbon isotope systematics in graphite is mainly governed by Rayleigh precipitation and/or by changes in temperature affecting the fractionation factor between fluid and graphite. Such processes result in zoned graphite crystals or in successive graphite generations showing, in both cases, isotopic variation towards progressive 13 C or 12 C enrichment (depending upon the dominant carbon phase in the fluid, CO 2 or CH 4 , respectively). In open systems, in which carbon is episodically introduced along the fracture systems, the carbon systematics is more complex and individual graphite crystals may display oscillatory zoning because of Rayleigh precipitation or heterogeneous variations of d 13 C values when mixing of fluids or changes in the composition of the fluids are the mechanisms responsible for graphite precipitation. ª 2011, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. All rights reserved.

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Section: Mixing Of Fluidsmentioning

confidence: 98%

Section: C-o-h Fluids With Two Carbon Speciesmentioning

confidence: 99%

Carbon isotopes of graphite: Implications on fluid history

Luque

Crespo-Feo

Barrenechea

et al. 2012

Geoscience Frontiers

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“…Studies on vein graphite deposits in India are scarce and were carried out some time ago (e.g., Krishna Rao and Malleswara Rao 1965;Acharya and Dash 1984;Soman et al 1986). However, more recent studies have dealt with graphite occurrences in these granulite rocks providing further evidence on the origin of the deposits (e.g., Santosh and Wada 1993a, b;Radhika and Santosh 1996;Satish-Kumar 2005;Baiju et al 2009;Satish-Kumar et al 2011). Vein graphite deposits in India, like those in Sri Lanka, are not restricted to any specific lithology but they are hosted by a wide diversity of metamorphosed sedimentary and igneous rocks (Acharya and Dash 1984;Acharya and Rao 1998).…”

Section: Granulite-hosted Depositsmentioning

confidence: 99%

“…On the other hand, graphite of biogenic origin which has been overgrown by graphite precipitated from a CO 2 -rich fluid released from decarbonation reactions or from mantle-derived CO 2 would also have a bulk isotopic ratio heavier than the typically low δ 13 C value of biogenic graphite. Mechanical mixtures of graphite derived from different carbon sources would also result in intermediate bulk isotopic signatures (e.g., Farquhar and Chacko 1991;Baiju et al 2009). Thus, even considering the data of stable carbon isotope ratios of graphite, the recognition of the biogenic or abiogenic origin can be difficult to prove in some instances as pointed out by Dissanayake (1981Dissanayake ( , 1986 for the vein deposits of Sri Lanka.…”

Section: Origin Of Carbonmentioning

confidence: 99%

Vein graphite deposits: geological settings, origin, and economic significance

et al. 2013

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Graphite deposits result from the metamorphism of sedimentary rocks rich in carbonaceous matter or from precipitation from carbon-bearing fluids (or melts). The latter process forms vein deposits which are structurally controlled and usually occur in granulites or igneous rocks. The origin of carbon, the mechanisms of transport, and the factors control-ling graphite deposition are discussed in relation to their geological settings. Carbon in granulite-hosted graphite veins derives from sublithospheric sources or from decarbonation reactions of carbonate-bearing lithologies, and it is transported mainly in CO 2 -rich fluids from which it can precipitate. Graphite precipitation can occur by cooling, water removal by retrograde hydration reactions, or reduction when the CO 2 -rich fluid passes through relatively low-fO 2 rocks. In igneous settings, carbon is derived from assimilation of crustal mate-rials rich in organic matter, which causes immiscibility and the formation of carbon-rich fluids or melts. Carbon in these igneous-hosted deposits is transported as CO 2 and/or CH 4 and eventually precipitates as graphite by cooling and/or by hydration reactions affecting the host rock. Independently of the geological setting, vein graphite is characterized by its high purity and crystallinity, which are required for applica-tions in advanced technologies. In addition, recent discovery of highly crystalline graphite precipitation from carbon-bearing fluids at moderate temperatures in vein deposits might provide an alternative method for the manufacture of synthetic graphite suitable for these new applications.

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“…Graphite found in disseminated forms in the metamorphosed sedimentary rocks are considered as biogenic (Landis, 1971). Whereas fluid deposited graphite commonly occur as veins, formed within the fractures and shears, although such graphite unusually also occurs as dissemination in the host rocks (Baiju et al, 2005(Baiju et al, , 2009. The graphite -host rocks relation, microscopic features of graphite and its carbon isotope signatures are significant in distinguishing graphites of various origins.…”

Section: Introductionmentioning

confidence: 99%