Evaluating formation fluid models and calibrations using clumped isotope paleothermometry on Bahamian dolomites

The clumped-isotope temperatures measured on the Bahamian dolomites (16-37 °C) agrees with the range of temperatures expected in the Bahamas. Pairing these temperatures with geological and mineralogical arguments, we favor the equation suggested by Matthews and Katz (1977), as it is the only one that produces realistic δ18O fluid values across the range of clumped-isotope temperatures. Both the clumped-isotope temperatures and δ18O values of the precipitating fluid show a strong positive covariance that we have interpreted as reflecting the mixing of surface brines that have undergone varying amounts of evaporation and normal seawater. The different mechanisms driving these fluids included formation by normal marine seawater driven by the compensatory flow of the mixing zone, bank wide Kohout convection, and evaporative brine reflux.