1993 Fiscal Year Final Research Report Summary
Minealogical and geochemical studies on water-rock interaction
| Project/Area Number |
04403013
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
鉱物学(含岩石・鉱床学)
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
TAKENO Setsuo Faculty of Science, Professor, 理学部, 教授 (00033829)
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| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Morihisa Faculty of School Educaton Assciate Professor, 学校教育学部, 助教授 (10033888)
HAYASAKA Yasutaka Faculty of Science, Research Associate, 理学部, 助手 (10198830)
HOSHINO Kenichi Faculty of Science, Research Associate, 理学部, 助手 (80190198)
KITAGAWA Ryuji Faculty of Science, Associate Professor, 理学部, 助教授 (70112167)
WATANABE Makoto Faculty of Science, Associate Professor, 理学部, 助教授 (80033900)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Liesegang texture / Pyrophyllitic alteration / Banded structure / Diffusion / Spherulitic texture / Water-rock interaction / Hematite / Minor element |
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| Research Abstract |
Pyrohyllitic alterton zone deeloped regonally in the shobara district, southwest Japan was investigated from te view point of water-rock interaction. Typical Liesegang textures(rings) were found in the upper most horizon of the alteration zone. The Liesegangu texture shows vivid color of purple, brownish purpe, pink and gray to white. Spherulitic txture ws also developed associated intimtely withthe liesegang textures. The iesegang texture is composed of alteration of white and dark colored bands and the width of the band is in the range between few millimeters and a few centimeters. The Liesegang texture is formed as the results of diffusion process during the regiona alteration. The most significant feature f the texture is that the band of Liesegang develoes in the direction perpendicular to the flow structure of the hst rhyolitic rocks.
Microscopic obsevation reveals that very fine ring of hematite less than about 100 microns developes in the dark color band. To be noted is that minor elements such as Nb, Zr, Sr and Mn are rich in white colored bands whereas iron is enriched in the dark colored band.
These facts strongy suggest that the regiona pyrophylitic aleration is characterized by certain difusion process of elements. Althugh most of the elements were derived from the host volcanic rocks, certain elements were contained originally in the reated hydrothermal solution.
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