日本における珪藻土の地質學的研究

概要

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Most Japanese diatomaceous earths occur, like foreign ones, in the formations belonging to the Neogene Tertiary, viz. Miocene and later. There are some distinct differences between the marine diatomaceous deposits and fresh-water deposits. Whether the origin of the earth is pelagic or Emilie, can be readily detectable by studying the assemblage of specks and by identifying the types of frustules. The diatom rich beds are commonly found in the Tertiary formations composing the oil fields along the coast of Japan Sea. These beds are of use in geologic research as key beds, if the rock facies and the floral, assemblages of fossil diatoms, are closely inspected. Besides, there are a good many localities in Japan, where deposits of diatomaceous earth of excellent commercial quality, which are mostly of fresh water origin, are found.