2002 Fiscal Year Final Research Report Summary
Development of a new paleopiezometer based on deformation microstructures : application to mantle flow
| Project/Area Number |
11440149
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Geology
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| Research Institution | Shizuoka University |
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Principal Investigator |
MICHIBAYASHI Katsuyoshi Faculty of Science, Associate Professor, 理学部, 助手 (20270978)
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| Project Period (FY) |
1999 – 2002
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| Keywords | Structual Geology / Mantle lithosphere / Oman ophiolite / Rheology / オマーンオフィオライト / レオロジー |
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| Research Abstract |
Structural and fabric analysis of the well-exposed Hilti mantle section, Oman ophiolite, suggests that shear zone development, which may have resulted from oceanic plate fragmentation, was influenced by pre-existing mantle fabric present at the paleo-ridge. Detailed structural mapping in the mantle section revealed a gently undulating structure with an east-west flow direction. A NW-SE strike-slip shear zone cuts across this horizontal structure. The crystal preferred orientation (CPO) of olivine within the foliation is dominated by (010) axial patterns rather than more commonly observed (010) [100] patterns, suggesting that the horizontal flow close to the Moho involved non-coaxial flow. Olivine CPO within the shear zone formed at low temperature is characterized by (001) [100] patterns and a sinistral sense of shear. The structural behavior of oceanic mantle lithosphere during subduction and obduction may be strongly influenced by initial mechanical anisotropy developed at an oceanic spreading center.
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