北海道夕張炭田地方に分布する古第三紀堆積岩のホウ素含量 : 古堆積環境指示元素としてのホウ素

概要

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The boron contents were determined by the methylene blue-1, 2-dichloroethane spectrophotometric method for fiftyseven sedimentary rock samples, and the availability of the element as a geochemical indicator for depositional paleoenvironment was discussed. On the average, the boron content is about 40ppm higher in the marine shales than in the terrestrial ones. The above difference becomes clearer on the illite fraction of the samples. It was, however, found that the boron content of the illite fraction of the Poronai formation samples differs significantly from that of the Wakanabe one, though these two formations had presumably been deposited under similar marine environment. The difference in the boron content of both formations could not be explained by the simple incorporation of boron into sediments from sea water during sedimentation. The above discrepancy may best be understood by assuming that the illite in the Poronai samples had contained considerable amounts of inherited boron before sedimentation. As a whole, boron may be useful to discriminate marine argillaceous sedimentary rocks from freshwater ones. However, the only negative feature for the element as a paleoenvironmental indicator is that a remarkable amount of inherited boron derived mainly from clay minerals could possibly be contained even in the sedimentary rocks of terrestrial origin.
日本地球化学会の論文
1980-03-30