大阪市におけるボーリング(OD-1)コアの花粉分析(その2) : 近畿地方の新期新生代層の研究 V

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A bore hole was drilled at a depth of 907m, at Tanakamoto-machi, Osaka City in 1963. As a result of it, it verified that the sediments found there are composed mainly of non-marine deposits intercalated with thirteen layers of marine clay, some of which can be regarded as being equivalent to that of the Osaka group (Plio-Pleistocene). Investigation of Pollen was carried on by the writer and the results are summerized as follows. 1. Metasequoia ranges up to Ma 2 layer and is never found in the strata stratigraphically above it. It was also inferred from the pollen analysis that Metasequoia died out during the deposition of the non-marine deposits lying under Ma 3 layer. The disappearance of the Metasequoia is thought to have been caused by lowering of temperature which begun during the deposition of the nonmarine deposits resting on Ma 0 layer. 2. Remarkable difference of flora can be observed between upper (III-a bed) and lower part of the Osaka group (III-b bed). This fact is concordant with the result of the pollen analysis. Namely, from the general floral ground, the Osaka group can be divided into upper and lower parts under the name of Fagus and Metasequoia zones respectably. 3. The marine clay layers found in the upper part of the Osaka group and the strata stratigraphically above it (IIIa-II), are considered to have been mostly deposited nnder the influence of warm temperature. On the other hand, the nonmarine beds found there were under the influence of cool or cold temperature. 4. From the percentage of Pinus and Alnus contained in above mentioned strata (III-a〜II), that provides evidence for sedimentary environment. It is safe to assum that, except Fr 3-4 and Fr 10-11 beds, non-marine layers were mostly deposited under a humid environment like a bog or a swamp. And some times the top or base of individual marine bed are considered to have experienced the same sedimentary environment. The abovementioned fact may provide good key for the condition of transgression or regression. Fr 3-4 bed is thought to be a lake or lagoonal deposits. The foregoing facts are profiled in fig. 7. Note: The term Fr 3-4 or Fr 10-11 beds mean non-marine bed found between Ma 3 and Ma 4 beds and between Ma 10 and Ma 11 beds, respectively.
1966-05-30

著者

田井昭子
京都市立加茂川中学校

大阪市におけるボーリング(OD-1)コアの花粉分析(その2) : 近畿地方の新期新生代層の研究 V

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