Climatic changes from the late Pliocene to middle Pleistocene in and around central Japan reconstructed from plant macrofossil assemblages

We used composition of plant macrofossil assemblages obtained mainly from the Osaka Group in central Japan to reconstruct the palaeoclimate between the late Pliocene (about 3.3 m.y. B.P.) and the middle Pleistocene (about 0.4 m.y. B.P.). The warmest climate of the period was before 3.0 m.y. B.P. Cool-temperate elements increased and subtropical elements decreased between 3 m.y. B.P. and 2.7 m.y. B.P., indicating the first climatic deterioration. The first occurrence of subarctic elements characterizes the Plio-Pleistocene boundary as a severe cold stage. After 1.1 m.y. B.P., climatic fluctuation occurred at less than 100,000 year intervals. A severe cold stage occurred just after the Jaramillo event (about 0.8 m.y. B.P.). The warmest stage in the middle Pleistocene occurred at about 0.5 m.y. B.P. With it evergreen broad-leaved forest expanded into central Japan. The climatic curves reconstructed from plant macrofossils parallel the climatic changes reconstructed from loess - paleosol stratigraphy in Central China, radiolarian faunal stratigraphy in the north Pacific deep sea drilling core, oxygen-isotope data in the North Pacific, and pollen spectra in western Europe.