埼玉県尾須沢鍾乳洞上に発達した土壌の鉱物・地球化学的研究  [in Japanese] Mineralogical and geochemical study of soils developed on Osuzawa limestone cave in Saitama Prefecture  [in Japanese]

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Abstract

本研究では埼玉県の鍾乳洞石灰岩上に発達する土壌を採取し、鉱物組成および元素・Sr同位体組成分析を行い、土壌形成過程および土壌鉱物の起源について検討を行った。X線回折の結果から鍾乳洞上に発達する土壌層からは石英、長石、粘土鉱物が同定された。石灰岩試料で検出された方解石は土壌中では見られなかった。また土壌のSr同位体比は石灰岩のそれとはわずかながら違う値であった。これらの結果から、土壌下部の石灰岩とは起源が異なる母材から土壌が形成されたことが示唆される。深度50cm以浅の土壌上層のSr同位体比は石灰岩よりわずかに低く、低いSr同位体比を示す火山噴出物の寄与が考えられる。深度50cm以深の土壌下層は石灰岩に含まれない粘土鉱物や長石に由来するAl, Ti, Fe, K, Baが濃集しており、そのSr同位体比は土壌上層や石灰岩よりもわずかに高い。これらの結果から、風化および土壌生成過程において大気起源物質,例えば降水や大気降下物、の寄与が考えられる。

This study was undertaken to determine mineralogical, elemental, and Sr isotopic compositions of soil collected in Saitama prefecture, eastern Japan and to evaluate the provenance and formation of soils developed on a limestone cave. X-ray diffraction analysis showed that soil samples developed on the limestone cave were composed of quartz, feldspar and clay minerals. The soils contained no calcite minerals, although the underlying limestone was composed mainly of calcite. Moreover their 87Sr/86Sr ratios were slightly different from those of the limestone. These results suggest that the minerals in the soils were not derived from the underlying carbonate rock. The upper soil samples (depth: <50 cm) showed slightly lower 87Sr/86Sr values than those of the limestone, indicating that the soil minerals originated from volcanic materials which had low Sr isotopic compositions. The lower soil samples (depth: >50 cm) were enriched in Al, Ti, Fe, K, and Ba, probably mainly from clay mineral and feldspar, and had higher 87Sr/86Sr ratios than those of the upper soils and the limestone. These results implicate contribution of atmospheric input, such as rainwater and/or eolian minerals, during soil weathering and formation process.

Journal

  • The Science and engineering review of Doshisha University

    The Science and engineering review of Doshisha University 48(1), 57-61, 2007-04

    Science and Engineering Research Institute of Doshisha University

Codes

  • NII Article ID (NAID)
    110006334677
  • NII NACSIS-CAT ID (NCID)
    AN00165868
  • Text Lang
    JPN
  • Article Type
    departmental bulletin paper
  • Journal Type
    大学紀要
  • ISSN
    00368172
  • NDL Article ID
    8770898
  • NDL Source Classification
    ZM2(科学技術--科学技術一般--大学・研究所・学会紀要)
  • NDL Call No.
    Z14-22
  • Data Source
    NDL  NII-ELS  IR 
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