Synthetic fluid inclusions: XIII. Experimental determination of PVT properties in the system H{sub 2}O + 40 wt% NaCl + 5 mol% CO{sub 2} at elevated temperature and pressure

Journal Article · Sun Oct 01 00:00:00 EDT 1995 · Geochimica et Cosmochimica Acta

DOI:https://doi.org/10.1016/0016-7037(95)00258-2· OSTI ID:505163

Schmidt, C; Rosso, K M; Bodnar, R J ^[1]

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1. Virginia Polytechnic Institute and State Univ., Blackburg, VA (United States)

The location of the liquid + vapor {yields} liquid phase boundary and the P-T slopes of iso-Th lines were determined for a constant composition of 40 {+-} 0.1 wt% NaCl 5 {+-} 0.15 mol% CO{sub 2} (both relative) to H{sub 2}O at high density. Synthetic fluid inclusions with this composition were formed in cold-seal pressure vessels at pressures of 2 and 4 kbar and temperatures between 350{degrees}C and 700{degrees}C. The inclusions were analyzed on a gas-flow heating/cooling stage to determine the temperatures of halite dissolution [Tm{sub (H+L+V{yields}L+V)}] and total homogenization [Th{sub (L+V{yields}L)}]. Addition to 40 wt% NaCl to an aqueous solution containing 5 mol% CO{sub 2} causes a significant shift of the liquid + vapor {yields} liquid boundary towards higher pressures. The slopes of the iso-Th lines decrease from 29.5 bars/{degrees}C for Th{sub (L+V{yields}L)} of 400{degrees}C, to 6.4 bars/{degrees}C for Th{sub (L+V{yields})} = 600{degrees}C. Addition of 5 mol% CO{sub 2} to an aqueous solution containing 40 wt% NaCl results in halite dissolution temperatures that are slightly higher (Tm{sub (H+L+V{yields}L+V)} {approx} 332{degrees}C) than the literature value of 323{degrees}C for the vapor-saturated liquidus of an H{sub 2}O-40 wt% NaCl mixture. Calculated molar volumes for 40 wt% NaCl + 5 mol% CO{sub 2} solutions at 2 and 4 kbar show trends that are similar to those of other compositions in the ternary system H{sub 2}O-CO{sub 2}-NaCl at the same pressures and temperatures. In the P-T range of this study, all excess volumes are negative and lie between the values for the compositions H{sub 2}O-5 mol% CO{sub 2} and H{sub 2}O-40 wt% NaCl. 30 refs., 6 figs., 2 tabs.

• OSTI ID: 505163
• Journal Information: Geochimica et Cosmochimica Acta, Vol. 59, Issue 19; Other Information: PBD: Oct 1995
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
58 GEOSCIENCES
SODIUM CHLORIDES
INCLUSIONS
SYNTHESIS
GEOCHEMISTRY
PHASE CHANGE MATERIALS