奈良盆地における最終氷期,20,000年前頃の花粉化石の変遷〔英文〕

概要

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Based on changes in facies, the Pleistocene Yamanobe Formation in the Nara Basin is divided into three members, the Upper Silt, Middle Peat and Lower Sand Members. Six pollen diagrams of the Last Glacial deposits, around the 20, 000 years ago, from the Yamanobe Formation together with the Nanmatsu Formation, which developed in the eastern part of the Nara Basin, are presented. Pollen from the Lower Sand Member, about 30, 000 years ago, showed that an open habitat was extensive in the basin, and that deciduous broad-leaved trees accompanied by Cryptomeria existed in the areas surrounding the basin, suggesting a temperate climate. Pollen from the Middle Peat Member, in which the Aira-Tn ash is intercalated, provides good evidence for an open habitat similar to the preceding stage in the basin. Pinus subgen. Haploxylon as well as Tsuga, Quercus subgen. Lepidobalanus, and Betula in the surrounding area of the basin indicate a cool temperate climate. The fall of the Aira-Tn ash affected vegetation, but no specific changes could be detected. The vegetation changes recorded are thought mainly to be of the local environments at respective sites. As for the Upper Member, there is evidence for open and sparse vegetation in the basin that followed the preceding members, although Tsuga pollen is well represented after the Sakate ash fall which occurred about 10, 000 years ago.
日本第四紀学会の論文