Using Carbon Isotope Equilibrium to Screen Pedogenic Carbonate Oxygen Isotopes: Implications for Paleoaltimetry and Paleotectonic Studies

Figure 8

Plot of δ¹⁸O_carb versus δ¹⁸O of meteoric water for each soil shown in Figure 5. Isotherms have been calculated using Kim and O’Neil [49]. Black squares are the data from Cerling and Quade [25], and white squares are the multisoil pit means for Arizona (this study). The red star represents the mean measured δ¹⁸O_carb value for pedogenic carbonates from Gutierrez and Sheldon [27]; δ¹⁸O_water was based upon an independently reconstructed MAT of 13°C for the paleosols and a fractionation factor from Kim and O’Neil [49]. The blue star is the interpolated mean annual δ¹⁸O_water value from the OIPC [24]. The grey box shows the seasonally adjusted (March–September) modern range of δ¹⁸O_water values for the present day latitude and longitude. For modern soil sites without direct measurements of the δ¹⁸O of meteoric water (white squares), the OIPC was used to calculate the value.