Late Quaternary variation of lignin composition in core MD01-2421 off central Japan, NW Pacific

In order to understand the responses of terrestrial vegetation in central Japan to global climate changes, we have generated the record of lignin composition from Core MD01-2421 off central Japan in the NW Pacific during the last 145,000 years by tetramethylammonium hydroxide (TMAH)-pyrolysis-gas chromatography–mass spectrometry (GC/MS). The relative abundance of lignin was significantly low in early MIS-1 and MIS-5e and higher in MIS-5c to early MIS-4. This reflects glacial–interglacial changes in sea level and riverine runoff. The ratio of syringyl (S)- to vanillyl (V)-phenols (S / V ratio), which is a contribution index of angiosperms against gymnosperms, was lower in MIS-2, MIS-4 and MIS-6, reflecting the glacial–interglacial variation of air temperature. The ratio of cinnamyl (C)- to vanillyl (V)-phenols (C / V ratio), which indicates the contribution of grasses, was higher in late MIS-2, early-mid MIS-3 and MIS-6. The periods of higher C / V ratio correspond to the periods of lower sea surface temperatures (SSTs), suggesting a dry and cold climate in late MIS-2, mid-MIS-3 and MIS-6.