Extended Data Figure 9: Down-core model–data evaluation at four data-rich sites.
From: Very large release of mostly volcanic carbon during the Palaeocene–Eocene Thermal Maximum
a–p, Comparisons for four Ocean Drilling Program Sites (401, 865, 1,209 and 1,263) for which surface ocean pH has been reconstructed across the PETM (Fig. 2; this study and ref. 20). q, The palaeo-locations of these sites in the cGENIE Earth system model. a–p, Model–data comparisons are made for: wt% CaCO3 (a, e, i, m); δ13C values from bulk carbonate (b, f, j, n); and surface ocean pH (c, g, k, o). Panels d, h, l and p provide an orientation in time, showing the projected evolution of atmospheric δ13C from CO2 in the model. For wt% CaCO3 and δ13C of bulk carbonate, model points (resolved at 1-cm intervals) are plotted as filled yellow circles. Model-projected pH values (global and annual means, as in Fig. 3h and Extended Data Fig. 6a) and atmospheric δ13C values for CO2 are shown as continuous red lines. In all cases, observed data values are shown as asterisks. For Sites 865, 1,209 and 1,263, the age models—employing the original relative age-model constraints20 used to convert from model-simulated sediment depths (resolved at 1-cm intervals) at each location in cGENIE—were calculated using a constant detrital flux accumulation rate. The observed data are plotted on the respective Site-690-derived age models25. Both model-based and data-based age scales are synchronized to time 0 (PETM onset; horizontal line). See Supplementary Information for details.
