書誌事項
- タイトル別名
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- Paleostress-field analysis by en-echelon veins in the Atokura Formation, Kanto Mountains, central Japan.
- ガンコウ ミャク オ モチイタ カントウ サンチ アトクラソウ チュウ ノ コ オウリョクバ カイセキ
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En-echelon veins hosted by sandstone and mudstone of the Atokura Formation were examined to clarify the paleostress field in that formation which constitutes the Atokura Nappe in a northern part of the Kanto Mountains. The veins are morphologically classified into two groups:1) a similar fold type with smoothly curved limbs, the vein tips pinch out and are not linked to any other fractures (type A) and, 2) a chevron fold type, the vein tips linked to joints formed before the vein opening (type B). The two types show a different texture and assemblage of infilling minerals. The type A consists mostly of fibrous to polygonal quartz and chlorite with lesser amounts of calcite and albite, whereas the type B of polygonal to prismatic calcite and quartz with lesser amounts of plagioclase and chlorite. Regardless of the vein type, morphology of the en-echelon sigmoidal veins is represented by a similar fold, but that of bridges is close to a parallel fold. The presence of undulatory extinction and subgrains in the fibrous quartz and pressure-solution cleavage in the bridges, which are considered to have simultaneously formed, indicates that the en-echelon veins were formed in a brittle-ductile shear zone. According to the paleostress analysis with conjugate sets of type-A vein arrays, the maximum (σ1) principal stress axis is inferred to have been oriented in the NW-SE to NNE-SSW direction and horizontal, intermediate (σ2) principal stress axis vertical, and minimum (σ3) principal stress axis in the NE-SW to WNW-ESE direction and horizontal. The veining could have occurred during the formation of E-W trending open upright folds of the Upper Cretaceous Atokura Formation.
収録刊行物
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- 地質学雑誌
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地質学雑誌 108 (9), 575-590, 2002
一般社団法人 日本地質学会
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詳細情報 詳細情報について
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- CRID
- 1390282681212041088
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- NII論文ID
- 110003009747
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- NII書誌ID
- AN00141768
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- ISSN
- 13499963
- 00167630
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- NDL書誌ID
- 6311327
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- 本文言語コード
- ja
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- データソース種別
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- JaLC
- NDL
- Crossref
- CiNii Articles
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- 抄録ライセンスフラグ
- 使用不可
