海成"沖積層"の層相と細分問題について (沖積層特集号)

概要

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It is current opinions in Japan that the Alluvial or Holocene marine deposits distributed in the coastal regions are represented by younger deposits than the Würm maximum. In this paper, the writers made a discussion on the lithological facies and subdivision of the marine deposits, based on the results of study in Tokyo and western Kyushu, as follows:-(1) In the lowland area of Tokyo, the so-called Alluvial deposits are subdivided into three lithological units, namely I, II, and III formaions as shown in Fig. 1. Among these, the third one is correlated with the Pleistocene volcanic ash, as judged from the mineralogical analysis and radiocarbon dating.(2) In the Ariake and Shiranui Bay areas, western Kyushu, the Alluvial deposits are subdivided into the Ariake and the Shimabarakaiwan formations respectively.(3) From the results of the analyses on micro-fossil fauna, mineral composition, chemical components and engineering properties of the announced formations (Figs. 2 and 3), it would be emphasized that the so-called Alluvial marine deposits may be subdivided into two major lithological or stratigraphical units. The interrelation between the units is considered to be unconformable which might have resulted from the lowering of sea level.
日本第四紀学会の論文