Composition of fluid inclusions

Roedder, Edwin

doi:10.3133/pp440jj

Cited by 211 publications

(150 citation statements)

References 150 publications

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“…No visible water is present in most CO, inclusions, but it is possible that up to 20 vol.% H,O is not visible (Roedder, 1972). Clathrate melting was not observed.…”

Section: Groupmentioning

confidence: 98%

“…Roedder, 1984;Bakker & Jansen, 1991), (2) if water is present around the walls of the inclusions but is not visible (Roedder, 1972) Because the migmatites are deformed, however, the possibility that the C0,-CH, inclusions were once C0,-CH,-H,O inclusions from which H,O leaked or diffused must also be considered. This explanation is consistent with the interpretation that the density of the CO, inclusions is lower than predicted for fluid trapped during m'igmatization, but, as discussed above, is problematic in that it does not explain why H20-CO2 fluid inclusions in meta-igneous rocks did not experience similar loss of H20.…”

Section: Discussionmentioning

confidence: 99%

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Origin of CO₂‐rich fluid inclusions in leucosomes from the Skagit migmatites, North Cascades, Washington, USA

WHITNEY

1992

Journal Metamorphic Geology

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C0,-CH, fluid inclusions are present in anatectic layer-parallel leucosomes from graphite-bearing metasedimentary rocks in the Skagit migmatite complex, North Cascades, Washington. Petrological evidence and additional fluid inclusion observations indicate, however, that the Skagit Gneiss was infiltrated by a water-rich fluid during high-temperature metamorphism and migmatization.C0,-rich fluid inclusions have not been observed in Skagit metasedimentary mesosomes or melanosomes, meta-igneous migmatites, or unmigmatized rocks, and are absent from subsolidus leucosomes in metasedimentary migmatites. The observation that C0,-rich inclusions are present only in leucosomes interpreted to be anatectic based on independent mineralogical and chemical criteria suggests that their formation is related to migmatization by partial melting. Although some post-entrapment modification of fluid inclusion composition may have occurred during decompression and deformation, the generation of the C0,-rich fluid is attributed to water-saturated partial melting of graphitic metasedimentary rocks by a reaction such as biotite + plagioclase + quartz + graphite f AI,SiO, + water-rich fluid = garnet + melt + C0,-CH,. The presence of C0,-rich fluid inclusions in leucosomes may therefore be an indication that these leucosomes formed by anatexis., Based on the inferences that (1) an influx of fluid triggered partial melting, and (2) some episodes of fluid inclusion trapping are related to migmatization by anatexis, it is concluded that a free fluid was present at some time during high-temperature metamorphism. The infiltrating fluid was a water-rich fluid that may have been derived from nearby crystallizing plutons. Because partial melting took place at pressures of at least 5 kbar, abundant free fluid may have been present in the crust during orogenesis at depths of at least 15 km.

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“…No visible water is present in most CO, inclusions, but it is possible that up to 20 vol.% H,O is not visible (Roedder, 1972). Clathrate melting was not observed.…”

Section: Groupmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Origin of CO₂‐rich fluid inclusions in leucosomes from the Skagit migmatites, North Cascades, Washington, USA

WHITNEY

1992

Journal Metamorphic Geology

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“…% equiv. NaCI (Roedder, 1984). These hypersaline fluids are generally thought to be direct products of a separating volatile phase from a crystallizing magma.…”

Section: Vein-forming Fluidsmentioning

confidence: 99%

Orogenesis, high-T thermal events, and gold vein formation within metamorphic rocks of the Alaskan Cordillera

1993

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Mesothermal, gold-bearing quartz veins are widespread within allochthonous terranes of Alaska that are composed dominantly of greenschist-facies metasedimentary rocks. The most productive lode deposits are concentrated in south-central and southeastern Alaska; small and generally nonproductive gold-bearing veins occur upstream from major placer deposits in interior and northern Alaska. Oreforming fluids in all areas are consistent with derivation from metamorphic devolatilisation reactions, and a close temporal relationship exists between high-T tectonic deformation, igneous activity, and gold mineralization. Ore fluids were of consistently low salinity, CO2-rich, and had 6~SO values of 7%o-12%o and 6D values between -15%o and -35%o. Upper-crustal temperatures within the metamorphosed terranes reached at least 450-500 ~ before onset of significant gold-forming hydrothermal activity. Within interior and northern Alaska, latest Paleozoic through Early Cretaceous contractional deformation was characterised by obduction of oceanic crust, low-T/high-P metamorphism, and a lack of gold vein formation. Mid-Cretaceous veining occurred some 50-100 m.y. later, during a subsequent high-T metamorphic/magmatic event, possibly related to extension and uplift. In southern Alaska, gold deposits formed during latter stages of Tertiary, subduction-related, collisional orogenesis and were often temporally coeval with calc-alkaline magmatism.

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“…Previous works (Wahler, 1958;Goguel, 1963;Chaigneau, 1967;Roedder, 1972;Zimmer mann, 1972;Piperov and Penchev, 1973;Harris, 1981) showed that fluids in rocks are essentially water and carbon dioxide in addition to small quantities of hydrogen, carbon monoxide, nitrogen, methane and organic compounds, hydrogen sulphide, sulphur dioxide and rare gases. These fluids can be analysed by two kinds of analytical processes: punctual techniques like microthermometry (Roedder, 1972;Weisbrod et al, 1976;Cheilletz et al, 1984) and Raman spec trometry (Cheiletz et al, 1984) global techniques such as gas chromatography (Chaigneau, 1967;Behar, 1978;Andrawes and Gibson, 1979) and mass spectrometry (Zimmermann, 1972;Cheilletz et al, 1984;Muenow, 1973).…”

Section: Introductionmentioning

confidence: 99%

Manometric and mass spectrometric analysis of fluids in geological meterials.

Zimmermann

Jambon²,

Guyetand

1988

Geochem. J.

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A procedure of volatile analysis in rocks which permits quantitative estimation of all the volatile species of any geological interest is presented and illustrated by several examples. Gas extraction is per formed either by vacuum crushing or heating. A separation line using cold traps, oxidation (CO to CO2) and reduction (H20 to H2) furnaces permits to separate several fractions. At the end of each separation phase the pressure in the line is measured with a capacitance manometer before analysis of the gas mix ture with a mass spectrometer. Calibration is done periodically using standard gases stored in gauged bottles. The detection limits are 0.5 to 1. X 10-' mot H2O, 0.3 x 10-' mol C02 and about 0 .2 x 10' mol for H2, N2, CO, CH4 and Ar. Further species like organic compounds, S02 and H2S are detected but not determined. In the case of H2O and C02 the reproducibility is better than 4% . The conjunction of vacuum crushing, stepwise heating and size fraction analysis permits to separate components like: dissolved, adsorbed and vesicle trapped. In particular, effects of adsorption have been evaluated: it is a serious problem for , species like CO2 and H2O with finely crushed material. H2 and CO detected after thermal extraction when organic compounds are present in the sample reflect organic decomposition rather than any thermodynamic equilibrium attained upon rock formation .

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Composition of fluid inclusions

Cited by 211 publications

References 150 publications

Origin of CO₂‐rich fluid inclusions in leucosomes from the Skagit migmatites, North Cascades, Washington, USA

Origin of CO₂‐rich fluid inclusions in leucosomes from the Skagit migmatites, North Cascades, Washington, USA

Orogenesis, high-T thermal events, and gold vein formation within metamorphic rocks of the Alaskan Cordillera

Manometric and mass spectrometric analysis of fluids in geological meterials.

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Composition of fluid inclusions

Cited by 211 publications

References 150 publications

Origin of CO2‐rich fluid inclusions in leucosomes from the Skagit migmatites, North Cascades, Washington, USA

Origin of CO2‐rich fluid inclusions in leucosomes from the Skagit migmatites, North Cascades, Washington, USA

Orogenesis, high-T thermal events, and gold vein formation within metamorphic rocks of the Alaskan Cordillera

Manometric and mass spectrometric analysis of fluids in geological meterials.

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Origin of CO₂‐rich fluid inclusions in leucosomes from the Skagit migmatites, North Cascades, Washington, USA

Origin of CO₂‐rich fluid inclusions in leucosomes from the Skagit migmatites, North Cascades, Washington, USA