Last interglacial climate changes and environments of the Lesser Kuril arc, north-western Pacific

Abstract

Last Interglacial Age deposits were studied in detail with radiocarbon and 230Th/ 232Th and 234U/ 232Th-dating on Zelenyi and Tanfil’ev Islands. The deposits of two transgressions were distinguished (MIS 5e and 5a). The deposits of maximal transgression include warm marine diatom assemblages with subtropical species. The climate was warmer than modern. On Tanfil’ev Island, marine deposits were deposited under cooler conditions (MIS 5a), covered by lacustrine and peat bog deposits. 230Th/ 232Th and 234U/ 232Th-data (interval of 69.4 + 8.2–7.0 ka and 73.0 + 5.3–4.8 ka) were obtained from this terrestrial unit. Pollen spectra established some stages of vegetation development that reflect progressive cooling. The surface peat record shows pronounced cooling that correlates with the Late Pleistocene Glacial (MIS 4). During warming in the second half of the Late Pleistocene (MIS 3), the climate was similar to modern or slightly cooler, and forest vegetation occupied the land bridge that connected the Lesser Kurils with surrounding islands. The Last Interglacial Maximum caused considerable changes to landscape zones on the Southern Kurils. The specific paleolandscape changes on small islands depended upon significant changes in the configurations of land during oscillations in sea level. Volcanic activity was another regional factor influencing different landscape components.