Characterization of CO/sub 2/-CH/sub 4/-H/sub 2/O fluid inclusions by microthermometry and laser Raman microprobe spectroscopy: inferences for clathrate and fluid equilibria

Journal Article · Mon Jun 01 00:00:00 EDT 1987 · Geochim. Cosmochim. Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(87)90345-0· OSTI ID:7160170

Seitz, J C; Pasteris, J D; Wopenka, B

Microthermometry (MT) and laser Raman microprobe (LRM) spectroscopy were done on 33 synthetically produced CO/sub 2/-CH/sub 4/-H/sub 2/O fluid inclusions in quartz. At room temperature, the inclusions consist of an aqueous liquid, a CO/sub 2/-CH/sub 4/ supercritical carbonic fluid, and graphite. In all these inclusions, the melting temperature for solid CO/sub 2/ is less than that for the homogenization of the vapor bubble in the carbonic fluid. A method is described whereby MT data for CO/sub 2/-CH/sub 4/-H/sub 2/O inclusions can be projected within the CO/sub 2/-CH/sub 4/ binary phase diagram to infer CO/sub 2/:CH/sub 4/ ratios in the carbonic fluid. This method takes into account the formation of CO/sub 2/-CH/sub 4/ clathrate hydrate during MT analysis. The authors interpretation of the MT data indicates that CH/sub 4/ is preferentially partitioned into the clathrate over the coexisting carbonic fluid, in contradiction to the prediction from PARRISH and PRAUSNITZ'S (1972) model for clathrate equilibria. Comparison of LRM analyses on the bulk carbonic fluid and the residual carbonic fluid confirm the preferential partitioning of CH/sub 4/ into the clathrate. LRM analyses of the clathrate itself indicate that CH/sub 4/ occupies both types of cage sites in the clathrate structure, whereas CO/sub 2/ may only occupy one site. Two by-products of the combined LRM and MT analyses of the same inclusions are derivation of empirical ratios of Raman quantification factors for high-density CO/sub 2/-CH/sub 4/ fluids and the ability to determine CO/sub 2/:CH/sub 4/ ratios of inclusions whose MT data lie near the critical region for CO/sub 2/-CH/sub 4/.

• Research Organization: Washington Univ., St. Louis, MO (USA)
• OSTI ID: 7160170
• Journal Information: Geochim. Cosmochim. Acta; (United States), Vol. 51:6
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CARBON DIOXIDE
CONCENTRATION RATIO
PHASE DIAGRAMS
INCLUSIONS
GEOCHEMISTRY
MICROSTRUCTURE
STRUCTURAL CHEMICAL ANALYSIS
METHANE
QUARTZ
CHEMICAL COMPOSITION
CRITICAL TEMPERATURE
EQUILIBRIUM
GRAPHITE
PHASE STUDIES
PHASE TRANSFORMATIONS
SOLID SOLUTIONS
SPECTROSCOPY
THERMAL ANALYSIS
WATER
ALKANES
CARBON
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMISTRY
CRYSTAL STRUCTURE
DIAGRAMS
DISPERSIONS
ELEMENTAL MINERALS
ELEMENTS
HYDROCARBONS
HYDROGEN COMPOUNDS
MINERALS
MIXTURES
NONMETALS
ORGANIC COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SILICON COMPOUNDS
SILICON OXIDES
SOLUTIONS
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE
580400* - Geochemistry- (-1989)