Rates of carbon dioxide outgassing and calcite precipitation in travertine-depositing streams
The authors studied Falling Spring Creek, Virginia, over the course of a year to quantify rates of calcite precipitation resulting from CO/sub 2/ outgassing in the subsurface and at the surface of the earth. The creek begins in Warm River Cave and is formed by the mixing of a warm stream, fed by a thermal spring, and a cold stream, fed by shallow groundwater. The mixed water emerges at the surface as several springs and forms the surface stream that is characterized by travertine deposition, especially in the vicinity of riffles and falls. The authors used computerized geochemical models to calculate aqueous speciation, saturation states, and PCO/sub 2/ values. They also calculated masses of calcite and CO/sub 2/ transferred out of solution between pairs of sequential samples collected along the 5 km of flow path studied. Using measured stream velocity, they determined rates of CO/sub 2/ outgassing and calcite precipitation for comparison to values predicted by published rate models. In the summer and fall, the stream water is supersaturated with respect to calcite all along the flow path; in the high flow conditions the initial length of the stream is undersaturated. The water reaches a high degree of supersaturation before calcite precipitates. The relatively high concentrations of Mg and SO/sub 4/ in solution may act as kinetic inhibitors of calcite precipitation.
- Research Organization:
- Univ. of Virginia, Charlottesville (USA)
- OSTI ID:
- 6459505
- 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
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CARBONATE MINERALS
CARBONATE ROCKS
CARBONATES
CAVES
CAVITIES
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMISTRY
DEGASSING
FEDERAL REGION III
GEOCHEMISTRY
GROUND WATER
HYDROGEN COMPOUNDS
KINETICS
LIMESTONE
MINERALS
NORTH AMERICA
OXIDES
OXYGEN COMPOUNDS
PARTIAL PRESSURE
PRECIPITATION
REACTION KINETICS
ROCKS
SATURATION
SEDIMENTARY ROCKS
SEPARATION PROCESSES
TRAVERTINE
USA
VIRGINIA
WATER
WATER CHEMISTRY
WATER SPRINGS