Fig. 2: Potential mixing model among different alkenone producers revealed by the cross-plot of ratios of unsaturated methyl and ethyl C38-alkenones (C38ME:C38ET) and tetra-unsaturated alkenones percentage (C37:4%).
a Cross-plot of C38ME:C38ET and C37:4% using published surface sediments datasets35,36,45,46,47,48,49,100,101,102,103 and downcore results in this study (red diamond). Note the x-axis is in log-scale and the data points with C38ME:C38ET = 0 were plotted at the position of 0.01 for the convenience of data visualization. The SCS represents the South China Sea and Medi represents the Mediterranean. b C38ME:C38ET and C37:4% of the IODP U1385 samples measured in this work. The C38ME:C38ET and C37:4% show a significant positive correlation in the sample with C37:4% > 4%. c–e The potential mixing lines between Group 3 living in tropical-subtropical and Group 1 living in freshwater (c), between Group 3 living in tropical-subtropical and Group 2 (d), and between Group 3 living in tropical-subtropical and Group 3 living in high latitude cold water (e). The blue and orange shaded areas in (d, e) represent mixing lines with different endmembers of Group 3 C38ME:C38ET ratios. Detailed endmember descriptions are listed in Supplementary Note Table S1. Red and gray dots in (c, d) represent downcore measurements in this study and global surface sediment in previous works, respectively. Source data of this figure are provided as a Source data file.
