Retrograde methane-dominated fluid inclusions from high-temperature granulites of Rogaland, southwestern Norway

Journal Article · Sun Sep 01 00:00:00 EDT 1991 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(91)90371-B· OSTI ID:7049760

Van Den Kerkhof, A M ^[1]; Touret, J L.R. ^[2]; Maijer, C; Jansen, J B.H. ^[3]

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1. Univ. of Goettingen (Germany)
2. Free Univ., Amsterdam (Netherlands)
3. Univ. of Utrecht (Netherlands)

Non-aqueous inclusions in the high-grade (800-1,000C; 4kbar) metamorphic Rogaland region, southwestern Norway, consist of mixtures of CO{sub 2}-CH{sub 4}-N{sub 2}. In particular the fluid inclusions in quartz veins in migmatites are characterized by high CH{sub 4} concentrations and they were re-equilibrated at temperatures below 500C during isobaric cooling. Observations by microthermometry demonstrated several complicated sequences of phase transitions, including partial and metastable homogenization (at lower temperature than melting), and S-L or S-V transitions. The phase behavior reflects a wide variation in composition and molar volume. Fluid compositions were measured by Raman microspectrometry. By this method, also small amounts of graphite have been detected in CO{sub 2}-CH{sub 4} inclusions. The instantaneous formation of graphite in a CO{sub 2}-CH{sub 4} inclusion by induction of the argon laser beam has been observed which points to the metastability of the CO{sub 2}-CH{sub 4} mixture. The calculated densities of the observed fluid mixtures are relatively low, necessitating a revision of the earlier interpretation of these inclusions as containing pure high-density fluids. Inclusions in quartz, trapped after the peak of metamorphism, record fluid heterogeneity which may present evidence for fluid-deficient metamorphism during the retrograde M2-M3 metamorphism.

• OSTI ID: 7049760
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Vol. 55:9; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
GRANULITES
GEOCHEMISTRY
INCLUSIONS
CHEMICAL ANALYSIS
CHEMICAL COMPOSITION
GEOLOGIC HISTORY
GEOTHERMOMETERS
GEOTHERMOMETRY
GRAPHITE
METAMORPHISM
METHANE
NORWAY
PETROGENESIS
PHASE STUDIES
QUARTZ
RAMAN SPECTROSCOPY
ALKANES
CARBON
CHEMISTRY
DEVELOPED COUNTRIES
ELEMENTAL MINERALS
ELEMENTS
EUROPE
HYDROCARBONS
LASER SPECTROSCOPY
MEASURING INSTRUMENTS
METAMORPHIC ROCKS
MINERALS
NONMETALS
ORGANIC COMPOUNDS
OXIDE MINERALS
ROCKS
SCANDINAVIA
SPECTROSCOPY
THERMOMETERS
580000* - Geosciences