Dolomite-calcite equilibrium at 220 to 240[degrees]C at saturation vapour pressure: Experimental data

Journal Article · Sat Jan 01 00:00:00 EST 1994 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(94)90454-5· OSTI ID:5155247

Morrow, D W; Gorham, B L; Wong, J N.Y. ^[1]

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1. Institute of Sedimentary and Petroleum Geology, Calgary, Alberta (Canada)

Small amounts of dolomite and calcite were added as reactants to a series of CaCl[sub 2-]MgCl[sub 2] solutions with variable Ca:Mg ratios at temperatures of 220[degrees]C and 240[degrees]C at vapour pressure in sixty experimental runs. Dolomitization of calcite and calcitization of dolomite in these runs indicates that the value of log (aCa[sup 2+]/aMg[sup 2+]) in solutions at equilibrium with calcite and dolomite ranges from about 0.4 to 0.9 at these temperatures. This is in agreement with previous experimental work at higher and lower temperatures. These experimentally determined equilibrium log (aCa[sup 2+]/aMg[sup 2+]) values are less than calculated by thermodynamic based programs, such as SUPCRT and PTA, for equilibrium with ordered dolomite and those which may be calculated from calorimetric data obtained from ordered, ideal dolomite. This may indicate that the experimentally observed calcite-dolomite equilibrium is metastable and that the precipitated dolomites are imperfectly ordered. Precipitation of partially disordered, metastable dolomite of stoichiometric composition may be favoured over that of ideal dolomite at these temperatures for kinetic reasons.

• OSTI ID: 5155247
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Vol. 58:1; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
02 PETROLEUM
CALCITE
EQUILIBRIUM
DOLOMITE
LEAD ORES
PETROLEUM DEPOSITS
TEMPERATURE RANGE 0400-1000 K
ZINC ORES
CARBONATE MINERALS
GEOLOGIC DEPOSITS
MINERAL RESOURCES
MINERALS
ORES
RESOURCES
TEMPERATURE RANGE
400201* - Chemical & Physicochemical Properties
020200 - Petroleum- Reserves
Geology
& Exploration