ID | 117523 |
Title Alternative | Extracting-method of pyrite micrograins as an indicator for mudstone weathering
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Author |
Ishida, Keisuke
University of Tokushima
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Nishiyama, Ken-ichi
University of Tokushima
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Sato, Takeomi
Japan Conservation Engineers
Takekuma, Takahiro
Japan Conservation Engineers
Hasegawa, Shuichi
Kagawa University
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Keywords | mudstone weathering
slaking
framboidal pyrite
oxidation
hydroxidation
extracting methodology
HF-processing
biomineralization
oxygen minimum zone
anoxic event
Cretaceous
Fujikawa Shale
Monobegawa Group
non-accreted formation
Kurosegawa Terrane
environmental geology
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Content Type |
Departmental Bulletin Paper
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Description | Applying to the indicator of mudstone weathering, an extracting method of pyrite micrograins and the secondary materials formed by oxidation and hydroxidation was examined using water diluted HF (3%). Based on the condition of extracted materials, the weathering grade of the drilling-cores of the Lower Cretaceous Fujikawa Shale Formation was subdivided into Oxidized- (weathered), Fresh-Oxidized Coexistence-, and Fresh- (non-weathered) zones in the order from the ground surface. The Fresh Zone is identified by only occurrence of non-altered primary pyrite micrograins that originate a bio-chemical process in sedimentary stage, and are characterized by aggregation of framboidal (raspberry-like), tubal (pellet-like), cubic and dodecahedral shapes. In the Fresh-Oxidized Coexistence Zone, pyrite micrograins and the secondary materials (hematite, goethite and limonitic hydrous ferric oxides) formed by oxidation and hydroxidation of pyrite co-exist, whereas the Oxidized Zone is characterized by the occurrence of ferric secondary materials without primary pyrites. A pyrite-alternation model was proposed in relation with the progressing of slaking. The Extracting-method of pyrite micrograins is useful even the case that the pyrite peak is not detected by X-ray analysis because of lower containing percentage.
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Journal Title |
Natural Science Research
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ISSN | 09146385
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NCID | AN10065859
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Publisher | 徳島大学総合科学部
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Volume | 20
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Start Page | 25
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End Page | 33
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Sort Key | 25
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Published Date | 2006-12-22
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EDB ID | |
FullText File | |
language |
jpn
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TextVersion |
Publisher
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departments |
Science and Technology
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