Pollen analysis of the TKN2004 core from the late Pleistocene Takano Formation, central Japan

We have performed pollen analysis on a TKN2004 core of 54-meter length from the late Pleistocene Takano Formation, where 21 beds of marker tephra had already been recognized in the core and the sediments of which were correlated with MIS 3 to 6. The analysis is at 1,200-year intervals in the lower half and 500-year intervals in the upper half. Based on the results, 12 local pollen zones, namely, TKN2004-I to -XII zone, are identified in ascending order. Pollen zones I to III (158-13ka) are characterized by pollens of subarctic conifer trees, and correspond with the cold MIS 6 stage. Pollens of cool-temperate deciduous broad-leaved trees such as Fagus increased abruptly and are dominant in Zone IV (130-117ka), which corresponds to MIS 5e, that is, the Last Interglacial. Zone V (117-107 ka) is characterized by increasing numbers of subarctic conifer pollens associated with Cryptomeria pollens, suggesting the little cooler MIS 5d. Pollens of deciduous broad-leaved trees increase in Zone VI (107-99ka), suggesting a cool temperate mixed forest under the little warmer climate of MIS 5c. Zone VII (99-86ka) is composed of dominant subarctic conifer pollens associated with a small amount of temperate conifer pollens, and corresponds with MIS 5b. Pollens of deciduous broad-leaved trees increase considerably in Zone VIII (86-76ka) associated with Cryptomeria. This warmer stage is MIS 5a. Zone IX (76-61 ka) has abundant subarctic conifer pollens such as Picea and Pinus Haploxylon, and only a few broad-leaved tree pollens, and is regarded as the cold MIS 4 stage. Zone X to XII (61-38ka) is characterized by repetition of dominant subarctic conifer pollens and considerable amounts of deciduous broad-leaved tree pollens. This feature implies quasi-periodic climate changes and a little warmer climate than that of Zone IX. These 3 zones correspond to MIS 3. This pollen zoning can be correlated widely and precisely with the pollen zonings already analyzed at several sites in the Chubu district, central Japan, with the assistance of marker tephra beds. This fact means that the pollen zoning of TKN2004 core and its reconstruction of vegetation are confirmed to be reliable, suggesting also that the climate in the Chubu district has been greatly changed under the intense effect of global climate change.