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Strontium concentrations and ^dgr18O are commonly used to infer the gross composition of dolomitizing waters, yet the bases for such inferences are not firmly established. A new approach to calibrating these 2 parameters is suggested from analyses of a section of upper Tertiary dolomites from the Bahamas.
In an interval of dolomite, 120 m (394 ft) thick from a core taken on San Salvador Island, mole % MgCO3 is correlated positively with ^dgr18O, and negatively with strontium. Strontium substitutes mainly for calcium, thus the negative correlation with the mole % MgCO3. Dolomites are enriched between 3 to 7% in ^dgr18O as compared with coprecipitated calcite, and thus the positive correlation. These two covariations indicate the need to consider the stoichiometric coefficient of dolomites, and to normalize strontium concentrations and ^dgr18O with their respective stoichiometric coefficients before inferring their relationship with fluid composition.
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