Figure 4: Δ47-temperature relationships for
different groups of freshwater carbonates. Left:
Δ47-temperature relationship for all carbonate types
included in this study. Black line represents a linear, ordinary least
squares regression through the data. We find a strong relationship
between Δ47 and temperature for each group of data. We
find indistinguishable slopes between all groups of data, but find
statistically different intercepts between a majority of datasets (Table
3), suggesting that material-specific calibrations may be most
appropriate. Right: Derived comparison of our material-specific
calibrations to previously published clumped isotope calibrations. We
find statistically similar slopes between all of our material-specific
regressions and the slopes presented in Petersen et al. (2019) and
Anderson et al. (2021), showing a convergence of slope (temperature
dependence) throughout the studies. However, we find significant
differences in intercept between previously published work and most of
our derived calibrations (Table 3), indicating these calibrations are
systematically offset from each other.