Sedimentology and Geochemistry of Dolostones
Sedimentology and Geochemistry of Dolostones - The need has always existed for understanding the processes of dolomitization and the origin of thick sequences of dolostones. This need becomes even more critical because pre-Cretaceous dolostones commonly host economically important deposits of natural resources and fossil fuels. This publication was derived from an SEPM Research Symposium held in Raleigh, North Carolina, on September, 1986. The volume attempts to answer the questions: How have the concepts and models presented in other publications been applied to sedimentary dolomites, Have we gained new insights and awareness into the processes of dolomitization, and many others. The principal message of this publication is, whereas enormous progress has been made in dolostone research since 1965, the subject is ripe for further study.
Experimental Investigation of Sulfate Inhibition of Dolomite and its Mineral Analogues1
Published:January 01, 1988
David W. Morrow, Brian D. Ricketts, 1988. "Experimental Investigation of Sulfate Inhibition of Dolomite and its Mineral Analogues1", Sedimentology and Geochemistry of Dolostones, Vijai Shukla, Paul A. Baker
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Time series experiments relating to the dolomitization of calcite at 215° to 225°C in saline solutions of near-seawater salinity were conducted to ascertain the influence of sulfate and carbonate in solution on the rate of calcite dolomitization. A concentration of about 0.004M sulfate in solution prevented the dolomitization of calcite. At concentrations of less than 0.004M, dolomitization proceeded at a slower rate than in experiments where no sulfate was present. The final concentration of sulfate was controlled by the precipitation of anhydrite.
The presence of sulfate in solution did not prevent the direct precipitation of dolomite in experiments in which the solid reactants were carbonate minerals other than calcite (BaCO3 and 2PbCO3.PbOH). Also, the presence of sulfate in the calcite dolomitization experiments slowed the rate of calcite dissolution from 3 days in sulfate-free solutions to 6 or 7 days in sulfate-bearing solutions. These observations indicate that sulfate in solution may inhibit dolomitization primarily by retarding the rate of calcite dissolution, rather than by inhibiting the direct precipitation of dolomite from solution.
The rate of calcite dolomitization was greater in solutions with higher carbonate/bicarbonate concentrations. This provides some confirmation for hypotheses regarding the importance of carbonate in solution as a kinetic factor that expedites dolomitization.