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Fluctuations in the East Asian monsoon over the last 144ka in the northwest Pacific based on a high-resolution pollen analysis of IMAGES core MD01-2421
| Title: | Fluctuations in the East Asian monsoon over the last 144ka in the northwest Pacific based on a high-resolution pollen analysis of IMAGES core MD01-2421 |
| Authors: | Igarashi, Yaeko Browse this author | | Oba, Tadamichi Browse this author |
| Issue Date: | Jul-2006 |
| Publisher: | Elsevier B.V. |
| Journal Title: | Quaternary Science Reviews |
| Volume: | 25 |
| Issue: | 13-14 |
| Start Page: | 1447 |
| End Page: | 1459 |
| Publisher DOI: | 10.1016/j.quascirev.2005.11.011 |
| Abstract: | A high-resolution pollen analysis of IMAGES core MD01-2421 (45.83 m) from the northwest Pacific off central Japan was used to clarify the vegetation history of central Japan over the past 144 ka. An age model was constructed using the oxygen isotope stratigraphy of benthic foraminifera, 12 accelerator mass spectrometry (AMS) 14C datings, and two tephra layers with known eruption ages. The pollen temperature index Tp[=100×Tw/(Tc+Tw), where Tw is the sum of temperate taxa and Tc the sum of subalpine taxa] values were high during 129–119, 115–100, 82–76, 53–49, and 15–0 ka. Cool-temperate broad-leaved forests developed during the high-Tp periods and subalpine conifer forests grew during the low-Tp periods. The Tp fluctuated synchronously with summer insolation at 36°N, where the core was collected. During periods with abundant Cryptomeria or Sciadopitys (120–118, 115–89, 78–70, and 4–0.3 ka), the East Asian summer monsoon was stronger and the annual precipitation was greater in central Japan than at present (>2000 vs. 1500 mm). Fluctuations in the sea-surface temperature (SST) calculated from the oxygen isotopes of foraminifera in core MD01-2421 and changes in the strength of the summer monsoon were synchronous. The SST was determined by the currents passing over the core site, rather than by the strength of summer insolation. Northward movement (high SST) of the Kuroshio Current, which is under the influence of the summer Okhotsk high pressure, was strong near the summer insolation minima when precipitation was high, particularly around 116, 94, and 71 ka. Thus, the strengths of both summer insolation and the East Asian summer monsoon have determined the vegetation history of central Japan for the last 144 ka. |
| Relation: | http://www.sciencedirect.com/science/journal/02773791 |
| Type: | article (author version) |
| URI: | http://hdl.handle.net/2115/14721 |
| Appears in Collections: | 環境科学院・地球環境科学研究院 (Graduate School of Environmental Science / Faculty of Environmental Earth Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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Submitter: 大場 忠道
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