Marine and terrestrial climate changes at the northern Japan margin in the northwestern Pacific during the last 23,000 years

We investigated marine and terrestrial environmental changes at the northern Japan margin in the northwestern Pacific by analyzing biomarkers in Core GH02-1030 to clarify the climate linkage between the ocean and land. The UK"37-derived temperature record was characterized by cooling events at ~19.6 ka, ~15.8 ka (Oldest Dryas), ~12.1 ka (Younger Dryas) and ~10.1 ka, and the temperature drops were attributable to the southward displacement of the subarctic boundary, which presumably resulted from both the depressed North Pacific High and the enhanced Okhotsk High. Short-chain C14-C18 n-fatty acids, derived mainly from marine organisms, showed higher concentrations during the last deglaciation, reflecting an enhanced marine production caused by the stronger Aleutian Low. Abundance ratio of long-chain n-alkanes and long-chain n-fatty acids to lignin, which are indices of herb contribution, showed maxima at ~16 ka and ~11.5 ka, indicating the expansion of grassland in a cold and dry climate. Abundant lignin indicated a higher contribution of terrigenous organic matter during the last deglaciation, reflecting an enhanced coastal erosion of terrestrial soils due to sea level rise and/or an efficient inflow of higher plant debris to river waters during this period.