Figure 2
Abundance and carbon isotope composition data from n-alkanes and pyrogenic C (PyC) from ODP core 1146: (a) PyC content; (b) δ13C values of PyC (δ13CPyC); (c) C31/C27 n-alkane ratio; (d) Average δ13C values of long-chain n-alkanes (δ13CAlk); (e) Record of δ13C of atmospheric CO2 39; (f) The contribution of C4 taxa to combusted biomass based on carbon isotopic enrichment factor for PyC (εPyC-CO2); (g) C4 abundance based on carbon isotopic enrichment factor for n-alkanes (εAlk-CO2). Arrows indicate the overall trend in proxies. Two yellow bars show the area of uncertainty in reconstructing the relative prominence of C3 and C4 taxa based on εPyC-CO2 and εAlk-CO2, and thus the basis for the very conservative estimates of prominence of C4 taxa mentioned in the text of this paper.
