広島市地下の第四系から産出した貝化石の殻内沈殿物

概要

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The underground Quaternary deposits in Hiroshima City yield abundant fossil shells. Among them, Anodontia strearnsiana Oyama and Dosinella pencillata (Reeve) are the representatives, which contain drusy infill carbonates with such various colors as red, yellow and orange. Gray-to dark-colored deposits have filled inner side of the drusy carbonates. The mode of occurrence of the fossils suggests that the shells have been fossilized almost preserving their life position. Based on X-ray diffraction analyses, it is revealed that shells and drusy infills consist mostly of aragonite and calcite, respectively, and that the inner deposits are composed mainly of calcite, illite, feldspar and quartz. X-ray fluorescence analyses have clarified that colored-infill carbonates are richer in MnO and MgO and poorer in CaO and SrO than the shells and that the inner deposits have relatively higher SiO2, Al2O3 and K2O than the shells and infills
広島大学学校教育学部の論文