Unstable to stable transformations during dolomitization
- Michigan State Univ., East Lansing (USA)
Dolomitization of calcite at 218C in hydrothermal bombs resulted in a series of unstable precursors to the final product, stoichiometric, ordered dolomite. The first phase formed with high-Mg calcite with approximately 35 mol % MgCO{sub 3}. This was replaced by Ca-rich, poorly ordered dolomite that was, in turn, replaced by ordered, stoichiometric dolomite. The rate of dolomitization and the rate at which unstable phases transformed to stoichiometric dolomite was related to the Mg{sup 2+}/Ca{sup 2+} ratio of the solution. There was no simple relationship between the Mg{sup 2+}/Ca{sup 2+} ratio solution and that of the products. SEM analyses of the products are interpreted to indicate that the unstable to stable transformation occurs by three, possibly simultaneous, mechanisms: (1) The small rhombs in the final products indicate that new crystals continue to nucleate during the reaction. (2) The large rhombs indicate that overgrowths of the more stable phase grew on the less stable phase. (3) The very irregular interiors indicate that the initial unstable products underwent a intercrystalline-scale dissolution and reprecipitation replacement.
- OSTI ID:
- 6241346
- Journal Information:
- Journal of Geology; (USA), Journal Name: Journal of Geology; (USA) Vol. 98:5; ISSN JGEOA; ISSN 0022-1376
- Country of Publication:
- United States
- Language:
- English
Similar Records
Dolomitization kinetics in hydrothermal bombs and natural settings
Energetics of calcium-rich dolomite
Related Subjects
152002* -- Geothermal Data & Theory-- Properties of Minerals & Rocks
58 GEOSCIENCES
580000 -- Geosciences
ALKALINE EARTH METAL COMPOUNDS
CALCITE
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CHEMICAL REACTION KINETICS
CRYSTAL GROWTH
CRYSTAL STRUCTURE
CRYSTAL-PHASE TRANSFORMATIONS
DISSOLUTION
DOLOMITE
ELECTRON MICROSCOPY
KINETICS
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MICROSCOPY
MINERALIZATION
MINERALS
NUCLEATION
OXYGEN COMPOUNDS
PHASE STUDIES
PHASE TRANSFORMATIONS
PRECIPITATION
REACTION KINETICS
SCANNING ELECTRON MICROSCOPY
SEPARATION PROCESSES
STABILITY
STOICHIOMETRY
SYNTHESIS