Calibration of the phosphate δ18O thermometer with carbonate–water oxygen isotope fractionation equations

There are significant ambiguities concerning the accuracy of oxygen isotope fractionation equations commonly used to retrieve aquatic paleotemperatures from the δ18O value of phosphatic skeletal remains. This is mainly due to the lack of a certified phosphate standard value, discrepancies in measured standard values between laboratories, and differences in methodologies used to constrain phosphate–water fractionation. Depending on the equation...