Experimental determination of the calcite-dolomite equilibrium below 200[degree]C: Revised stabilities for dolomite and magnesite support near-equilibrium dolomitization models
- Exxon Production Research Co., Houston, TX (United States)
New hydrothermal experiments conducted in Dickson-type and Parr reaction vessels have delimited the calcite-dolomite and dolomite-magnesite equilibria between 125 and 200 C. These experimental data when combined with accurate heat capacities for minerals and ions, require significant increases in the standard enthalpies for the reactions: 2 Calcite + Mg[sup 2+] = Dolomite + Ca[sup 2+] (1), and Dolomite + Mg[sup 2+] = 2 Magnesite + Ca[sup 2+] (2). The revised standard heats are 20.2 kJ for Reaction (1) and 29.9 kJ for Reaction (2). These parameters permit accurate calculation of the calcite-dolomite and dolomite-magnesite equilibria from 0 to 400 C and yield results in excellent agreement with the high-temperature experiments of Rosenberg and Holland (1964, 1967). In consequence, seawater at earth-surface conditions is nearly at equilibrium with dolomite, not grossly supersaturated with it, and dolomitization is bets modeled as a near-equilibrium process. The authors illustrate this approach with models describing dolomitization by hot seawater and by evaporated seawater.
- OSTI ID:
- 5806840
- Report Number(s):
- CONF-921058--
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Journal Name: Geological Society of America, Abstracts with Programs; (United States) Vol. 24:7; ISSN GAAPBC; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
020200 -- Petroleum-- Reserves
Geology
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58 GEOSCIENCES
580000* -- Geosciences
ALKALINE EARTH METAL COMPOUNDS
CALCITE
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CHEMICAL REACTION KINETICS
DOLOMITE
ENTHALPY
EQUILIBRIUM
HYDROGEN COMPOUNDS
KINETICS
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MATHEMATICAL MODELS
MINERALIZATION
MINERALS
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
REACTION HEAT
REACTION KINETICS
SEAWATER
THERMODYNAMIC PROPERTIES
WATER