Figure 6

Relationship between (a) lacustrine authigenic carbonate oxygen isotope fractionation factors (1000lnα_{(carb−water)}) and lake summer water surface temperature (T_water) and modeled water temperatures (T_CW) by applying several published temperature calibrations^5,6,7,17; and (b) lake summer water surface temperature (T_water) and modeled water temperatures (T_CW) using the Daëron et al.¹⁷ calibration indicating temperature is not the dominant control on the δ¹⁸O of lacustrine authigenic carbonates sampled in Western China. Circles are data from thirty-three samples collected for this study. Black points refer to water temperatures directly recorded by on-site water temperature loggers (T_LMSW). Blue points refer to water temperatures for sites without data loggers and are calculated using the Eq. (1) and are reported as Calculated Mean Summer Water Temperature (T_CMSW). Similar results are obtained for both types of temperature data. Solid lines are least-square linear regression lines. Dashed line represents 1:1 (i.e. no difference) relationship.