The middle-late Pleistocene deposits composed of the Yasuda Formation, the Ominato sand bed, and the Banjin sand bed were formed at Kashiwazaki Plain in Niigata prefecture. Clarifying their stratigraphy and sedimentary environment is very important for revealing the paleoenvironment during the late Pleistocene in the Kashiwazaki Plain.
The Yasuda Formation is divided into an upper and a lower part. Both parts were formed with the character of valley fills because of a marin transgression under fresh or brackish water conditions in a bay which was separated from the open sea. The terrace surface of the upper part of the Yasuda Formation is correlative with the Shimosueyoshi surface in the south Kanto region.
The Ominato sand bed, newly named in this paper, comprises littoral or neritic sands, which cover the lower part of the Yasuda Formation conformably. The Nakago pumice layer (ca. 150-130ka) is intercalated near the boundary between the uppermost part of the Ominato sand bed and the Banjin sand bed, composed of eolian sands which cover the Ominato sand bed comformably. From to this it is inferred that the surface of the Ominato sand bed below emerged with the Yasuda terrace at the Shimosueyoshi stage; in addinon, the Ominato sand bed and upper part of the Yasuda Formation are heterotopic facies. Under the influence of the paleoenvironment, the bar which consisted the Ominato sand bed was formed in front of Kashiwazaki Plain and the upper part of the Yasuda Formation was deposited in the lagoon behind the bar at the Shimosueyoshi transgression stage. This suggests that a barrier system was present at that stage.
There existed a bar at the beginning of the regression. Because of the regression, the lagoon dried up and formed the Yasuda surface. After the Yasuda Formation and the Ominato sand bed emerged, the Banjin sand bed which was composed of eolian sands was deposited at the Shimosueyoshi stage; the Obaradai stage and the other regression stages emerged later. The Old Dune sand has remained for almost fifty thousand years.

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The process by which siliceous remains disappear and the change in species composition of thanatocoenoses were investigated in comparison with biocoenoses in Nagano-yama Wetland, Aichi Prefecture, Japan.
The number of diatom frustules and contents of reactive silica extracted by alkaline solution were rapidly decreased toward the lower part of the core. Dissolution of the remains was selective. Thus destruction of theca plates of amoeba was not so severe as in diatom frustules, and in the diatom assemblage, Frustulia rhomboides with thickened longitudinal-ribs only remained in the lowest part of the core.
This study suggests that interpretation of paleoenvironment based on the shift in species composition may be strongly biased by selective destruction of the remains.

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Electron spin resonance (ESR) spectra of quartz grains less than 20μm have been measured to identify the source areas of eolian dust. Thirty-seven samples of loesses, soils, paleosols and bore cores were measured: five Upper Malan loess from China, two loessderived soils on the lower terraces and one Holocene soil from Korea, nine Peoria loesses from the USA, two red soils on weathered Precambrian rocks from China and Korea, and twelve samples from Kurota bore-cores and six paleosols from the Tottori and Amino coastal sand dune fields along the Japan Sea coast in Japan. Upper Malan loess, Korean loessderived soils and Peoria loess were deposited during isotope stage 2. Kurota bore cores and the paleosols of Tottori and Amino were correlated with the last Glacial age.
Chinese loess quartz showed measurement values ranging from 5.8 to 8.3 (in arbitrary units), and red soil on the weathered Precambrian rock was 12.4. Korean soil quartz showed values ranging from 6.0 to 7.7, and red soil was 11.2. Peoria loess quartz originating in the Canadian Precambrian Shield showed values of ranging from 11.0 to 14.0. Kurota eolian dust quartz showed values of ranging from 5.8 to 8.5. Kurota fluvial quartz showed a range from 3.3 to 4.7 originating in the Paleosoic rocks of the surrounding area. Eolian dust quartz contained within paleosols at Tottori and Amino showed lower values, ranging from 3.7 to 4.8. Paleosol quartz of isotope stage 4 horizon in Tottori was 5.9, coinciding with the values of Chinese loess quartz. These values indicate that eolian dust from the Asian continental areas was deposited in large quantities into the paleosols during isotope stage 4 as well as stage 2. Paleosol quartz mixed with much of the Daisen tephra quartz showd the low value of 1.9.
To Summarize the results of the experiment: Precambrian quartzes from three countries have a similar range of intense signals, from 11.0 to 14.0, while fluvial quartzes originating in the surrounding Paleosoic area in Japan vary in the range from 3.3 to 4.7. The quartzes of Chinese loess and Korean soils are remarkably similar to ranges of ESR intense signal. This similarity is attributed to their common eolian origin in the arid and semi-arid Asian continental areas during isotope stage 2. Japanese eolian dust quartz varies over a wide range, from 3.7 to 8.5. It is concluded that the origins of one group of Japanese eolian dust, with ESR signal intensity ranging from 5.8 to 8.5, may be the Asian and and semi-arid areas such as the Tibetan Plateau, Taklamakan, and the Gobi desert. Another group, having ESR signal intensity ranging from 3.7 to 4.8, such as paleosols in the dune fields, may come from the dried sea floor during the last Glacial age.
Eolian dust quartz isolated from loess, soils, paleosols, and bore cores in East Asia is remarkably uniform in ESR signal intensity, and is a useful tracer for the provenance of the quartz.

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[in Japanese]

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