The Takano Formation in Nagano City, central Japan consists of Late Pleistocene lacustrine sediments. An undisturbed core of 53.88 m in length was collected by double tube core barrel system in June 2004. The sediments are almost clayey silt, and intercalated a large number of tephra layers, some of which are widespread marker tephras. Ages were estimated from the radiometric determinations of five wide-spread marker tephras such as DKP, Aso-4, K-Tz, Ata, and Aso-2, although it was presumed that sedimentation rate was constant.
The TOC variations from around 169 ka to 37 ka, are concordant with those of the pollen compositions reported in previous studies for the outcrops of the Takano Formation. Paleoclimate changes from around 169 ka to 37 ka have been reconstructed by TOC in sediments of the Takano Formation in about 28 year interval, which shows long periodicities as a few tens thousands years. It is found that the TOC variations can be correlate with the marine
δ18O curve of SPECMAP from MIS 6 to early MIS 3. The values of TOC are high in MIS 3 and 5, while low in MIS 4 and 6. In addition, the TOC variations during MIS 5 can be correlated with the substages such as MIS 5a, 5b, 5c, 5d and 5e.
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