Extended Data Fig. 2: Comparison between different TEX86-to-SST calibrations and different GDGT ratios.
From: Synchronous tropical and polar temperature evolution in the Eocene
a, TEX86–SST calibration lines (trend lines for BAYSPAR) for one logarithmic and several linear calibrations. Plotted symbols are the Site 959 TEX86 record, to illustrate which part of the calibration is relevant for this study. Compared calibrations are: BAYSPAR19,41 with default settings (search tolerance for 2 TEX86 standard deviations, 0.13; dark-grey line, dark-grey diamonds), BAYSPAR with increased search tolerance (0.2) (dashed line, light-grey diamonds), Kim et al.18 logarithmic \({{\rm{TEX}}}_{86}^{{\rm{H}}}\) core-top calibration (red line, red diamonds), linear core-top calibration18 (light-blue line) and linear subset core-top calibration without Red Sea and polar ocean data18 (dark-blue line). It is of note that the logarithmic \({{\rm{TEX}}}_{86}^{{\rm{H}}}\) starts strongly diverging from the linear BAYSPAR and subset calibrations from TEX86 values of >0.8. b, Site 959 SST record using different TEX86 calibrations. Calibrations and line colours and types are as in a. c, Ratio of crenarchaeol to GDGT-0 against TEX86. Data are from a core-top compilation41 (black circles; Red Sea subset, purple circles) and our Site 959 record (red squares). d, Ring index sensu Zhang et al.50 against TEX86. Data are from a core-top compilation (black circles; Red Sea subset, purple circles) and our Site 959 record (red squares). The exponential regression line of Zhang et al. through the core-top data is plotted as a black line.
