This paper reports the fractionation of Δ47 during the digestion of dolomite in phosphoric acid between 25°C and 90°C using five different samples, including three of Pliocene age from the Bahamas, one from the Jurassic in the Middle East, and one obtained from the National Institute of Standards (NIST 88b). The composition of the dolomites analyzed varied from Ca0.56Mg0.44CO3 to Ca0.50Mg0.50CO3. Fractionation values were also compared between the common acid bath and sealed vessel techniques at various temperatures. No statistically significant differences were observed either between these two methods or as a function of the dolomite's stoichiometry.These data produce a difference in fractionation of 0.153±0.011‰ for dolomite samples digested at 90°C compared to those reacted at 25°C, a value higher and statistically different to previously published values. Utilization of this value in a study of dolomites from a core drilled on the island of San Salvador in the Bahamas yielded temperatures and δ18Ofluid values which agree with previous interpretations on the formation of these dolomites. Application of this value to other published studies produces lower estimates of temperature and δ18Ofluid values for the dolomitization process that are more consistent with the geologic models suggested for these studies.
ASJC Scopus subject areas
- Geochemistry and Petrology