Variations between weathered pumice particles of the Nantai-Shichihonzakura and Nantai-Imaichi tephra from polished sections

Masami Nanzyo, Hideaki Hirai, Kumiko Ito, Hitoshi Kanno

Research output: Contribution to journalArticlepeer-review

Abstract

The oxalate-extractable Al (Alo) of weathered Nantai-Imaichi (Nt-IK) tephra sampled at Kiwadajima in Tochigi Prefecture, Japan is more than twice as high as that of weathered Nantai-Shichihonzakura (Nt-SK) tephra. This difference is peculiar because the Nt-IK horizon is directly under the Nt-SK tephra, without a buried A horizon in between, and the Nt-IK compares with the Nt-SK in age. The scanning electron microscopic image of the polished section of the pumice prepared from the Nt-SK tephra indicated the presence of weathered product, which would be allophanic altermorph of the thin bubble-wall glass as determined by energy-dispersive X-ray analyses. The unweathered thick bubble-wall glass was also present in the Nt-SK pumice typically accompanied with the weathered product as a thin film on the periphery. In contrast, the Nt-IK tephra lacks unweathered glass, with almost all glass converted to allophanic materials. One of the reasons for the high Alo value of the Nt-IK tephra compared with the Nt-SK is that the former has almost no unweathered glass whereas the latter has them inside the thick bubble-wall glasses.

Original languageEnglish
Pages (from-to)693-701
Number of pages9
JournalSoil Science and Plant Nutrition
Volume66
Issue number5
DOIs
Publication statusPublished - 2020

Keywords

  • Andisol
  • Andosol
  • Volcanic glass
  • allophane
  • altermorph

ASJC Scopus subject areas

  • Soil Science
  • Plant Science

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