Experimental Study of the PVTX Properties in Part of the Ternary System H₂O-NaCl-CO₂

Phase equilibria and volumetric properties in the system water-sodium chloride-carbon dioxide were determined experimentally for pressures between about 1 to 6 kbar, temperatures of 300° to 800°C, and fluid compositions up to 40 wt% NaCl and 20 mol% carbon dioxide, both relative to water. This was accomplished by using the synthetic fluid inclusion technique in conjunction with conventional microthermometry, a hydrothermal diamond-anvil cell and Raman spectroscopy. At constant salinity, the high-pressure portion of the solvus migrates to higher pressures and temperatures with increasing carbon dioxide concentration. Immiscibility is possible in this ternary system over almost the entire range of crustal P-T conditions at salinities equal to or in excess of 20 wt% NaCl and carbon dioxide concentrations between about 30 and 70 mol% carbon dioxide. The dP/dT slopes of lines of equal homogenization temperature decrease nonlinearly with increasing homogenization temperature; at constant homogenization temperature, these slopes become steeper (higher) along pseudobinaries with addition of carbon dioxide and particularly with addition of sodium chloride. Up to concentrations of 20 wt% NaCl and 20 mol% carbon dioxide, a sharp rise in the critical temperature was observed with increasing salinity at a fixed water/carbon dioxide ratio. The critical point shifts rapidly towards higher pressures with increasing carbon dioxide concentration. Addition of carbon dioxide to an aqueous 40 wt% NaCl solution results in a slight elevation of the halite dissolution temperature under vapor-saturated conditions. A significant error can be associated with the calculation of molar volumes from measured densities of the carbonic phase of water-sodium chloride-carbon dioxide inclusions. To avoid such errors, phase diagrams were constructed based on the obtained lines of equal homogenization temperature for salinities between 6 and 40 wt% NaCl and carbon dioxide concentrations between 5 and 20 mol% relative to water. These diagrams are of direct applicability to the interpretation of natural fluid inclusions from a wide variety of geologic environments.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Geological Sciences

Department dc:contributor.department

Geological Sciences

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1997

Author dc:creator

• Schmidt, Christian

Chair dc:contributor.committeechair

• Bodnar, Robert J.

Committee members dc:contributor.committeemember

• Chou, I. M.
• Craig, James R.
• Tracy, Robert J.
• Roedder, E.

• raman spectroscopy
• synthetic fluid inclusions
• PVTX properties
• water - sodium chloride - carbon dioxide
• hydrothermal diamond-anvil cell

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

etd-566232139711101

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/30610