Novel Stable Isotopes

Triple Oxygen Isotopes

In modern waters and paleoclimate records such as ice cores, deuterium-excess (d-excess) or the deviation of δ18O and δD from the global meteoric water line (GMWL) has been used extensively to quantify evaporative effects; however, the application of d-excess to the rock record is limited because of the lack of co-occurring O- and H- mineral phases. 

Studies of the relationship between 16O, 17O, and 18O (triple oxygen isotopes) have shown that these isotopes are sensitive to evaporation similar to d-excess in water. Studies of the relationship between δ18O and δ17O have resulted in a triple oxygen isotope anomaly or Δ17O (similar to d-excess), which represents the deviation from the slope of the GMWL (0.528) on a δ’18O vs. δ’17O plot (Landais et al., 2010; Luz and Barkan, 2010). Evaporation results in an increase in δ18O and decrease in Δ17O in waters (Fig. A), such that soil waters in arid settings which have potential for evaporation should have Δ17O values that are equivalent to or lower than the observed range of global precipitation (Fig. B).