Variable dissolution rates of deformed and undeformed calcite
The rate of dissolution of plastically deformed, polycrystalline calcite relative to undeformed, polycrystalline calcite has been measured by free drift experiments in CO/sub 2/ saturated solutions at 24/sup 0/C. Total Ca/sup + +/ and pH were recorded throughout the experiments. Results show that deformed calcite dissolves at a measurably higher rate than undeformed calcite. Over a total change in pH of approximately 1.4 pH units the measure difference between the deformed and undeformed samples is on average 0.35 pH units, which corresponds to 25% of the total. Transmission electron microscopy reveals that the deformed calcite contains high densities of dislocations and twins; the undeformed calcite is relatively free of defects. The most significant difference in the rates of dissolution occurs during the first 30 minutes. For the remaining 180 minutes the rates are comparable, suggesting that the initial rate difference is due to the surface characteristics of the sample, which are destroyed after 30 minutes. Additional studies have determined the effect of grain size on the rate of dissolution. These observations suggest that the presence of dislocation and other defect microstructures may affect the dissolution, and hence preservation, of calcite constituents during early diagenesis.
- Research Organization:
- State Univ. of New York, Stony Brook (USA)
- OSTI ID:
- 6595521
- Report Number(s):
- CONF-8510489-
- Journal Information:
- Geol. Soc. Am., Abstr. Programs; (United States), Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Vol. 17; ISSN GAAPB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580400* -- Geochemistry-- (-1989)
ALKALINE EARTH METAL COMPOUNDS
CALCITE
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CALCIUM IONS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CHARGED PARTICLES
CHEMISTRY
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DEFORMATION
DIAGENESIS
DISSOLUTION
GEOCHEMISTRY
GRAIN SIZE
IONS
KINETICS
MICROSTRUCTURE
MINERALS
OXYGEN COMPOUNDS
PH VALUE
REACTION KINETICS
SIZE
SOLUBILITY
SOLVENT PROPERTIES