Abstract
Core MD01-2421, located off Kashima, in the Northwest Pacific, contains a continuous record of deposits over the past 144 ky, as dated by the AMS 14C method, tephrochronology, and the oxygen isotope stratigraphy of benthic foraminifera. Temporal changes in Tp (pollen temperature index) values reveal two warm periods (MIS 5.5 and late MIS 2 to MIS 1), three cool periods (mid-MIS 5.4 to the first half of MIS 5.3, the latter half of MIS 5.1, and early MIS 3), and two cold periods (MIS 6 and all of MIS 2 except for the latter part). Cool temperate deciduous broad-leaved forests (mainly Quercus subg. Lepidobalanus, Fagus, Quercus subg. Cyclobalanopsis, and Juglans/Pterocarya) developed during the warm periods, whereas the cold periods were dominated by subarctic coniferous forests of Picea, Tsuga, and Larix. Following each of the warm and cool periods, Cryptomeria japonica and Sciadopitys verticillata flourished under wet climatic conditions that arose due to strengthening of the East Asian Summer Monsoon. The climate cooled after each of the maximum monsoon periods, resulting in an increase in subarctic conifers. In the southern Kanto district, near the MD01-2421 site, the vegetation history since MIS 5.5 has been divided into four periods (A-D) based on pollen assemblages and plant macrofossils, with age control provided by several tephra layers. The data obtained from the marine and land sites are well correlated, showing similar patterns of vegetation change and comparable age data. Period A is correlated with MIS 5.5 (130-117.3 ka), B with MIS 5.4-5.1 and 4 (117.3-59 ka), C with MIS 3 and 2 (59-12 ka), and D with MIS 1 (12 ka to the present). In comparing pollen data since MIS 5.5 with eight other areas in Japan, data from Lake Biwa, Lake Suwa, and Okute Basin in central Honshu Island correspond well to those from core MD01-2421.
