Fig. 5: Lignin source proxies in subsea permafrost. Subsea permafrost data represent the thaw fronts of cores 4D-13, 2D-13, and 4D-12 from the Buor-Khaya Bay.

S/V syringyl/vanillyl, C/V cinnamyl/vanillyl. Gray areas indicate ranges of different plant tissue types14,63,71,72,73,74. Data from previous studies in northeast Siberia are shown for comparison (means ± standard deviation), including Buor-Khaya Bay surface sediments (mar. sed.)14,42,48, Lena River suspended matter, Ice Complex deposits (ICD)14,48, Holocene peat permafrost (pf.)14, and active layer (AL) material from tundra and boreal forest (taiga) locations48.