open access

https://hdl.handle.net/2115/51231

Biomarker records from core GH02-1030 off Tokachi in the northwestern Pacific over the last 23,000 years: Environmental changes during the last deglaciation

英語

paleotemperature

2009-12

Springer

Journal of Oceanography

65(6)

847-858

We investigated marine and terrestrial environmental changes at the northern Japan margin in the northwestern Pacific during the last 23,000 years by analyzing biomarkers (alkenones, long-chain n-alkanes, long-chain n-fatty acids, and lignin-derived materials) in Core GH02-1030. The UK'37-derived temperature in the last glacial maximum (LGM) centered at 21 ka was ~10˚C, which was 2˚C lower than the core-top temperature (~12˚C). This small temperature drop does not agree with pollen evidence of a large air temperature drop (more than 4˚C) in the Tokachi area. This disagreement might be attributed to a bias of UK'37-derived temperature within 2.5˚C by a seasonal shift in alkenone production. The UK'37-derived temperature was significantly low during the last deglaciation. Because this cooling was significant in the Kuroshio-Oyashio transition zone, the temperature drops are attributable to the southward displacement of the Kuroshio-Oyashio boundary. Abundant lignin-derived materials, long-chain n-alkanes and long-chain n-fatty acids indicate a higher contribution of terrigenous organic matter from 17 to 12 ka. This phenomenon might have resulted from an enhanced coastal erosion of terrestrial soils due to marine transgression and/or an efficient inflow of higher plant debris to river waters from 17 to 12 ka.

学術雑誌論文

Accepted Manuscript

0916-8370

1573-868X

AA10833529