Generation and driving forces of plate-like motion and asymmetric subduction in dynamical models of an integrated mantle-litho sphere system
Physics of the Earth and Planetary Interiors 166 巻 3-4 号
128-146 頁
2008-02 発行
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PEPI_166_128.pdf
2.25 MB
種類 :
全文
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タイトル ( eng ) |
Generation and driving forces of plate-like motion and asymmetric subduction in dynamical models of an integrated mantle-litho sphere system
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作成者 |
Hamada Chiho
Tagawa Michio
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収録物名 |
Physics of the Earth and Planetary Interiors
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巻 | 166 |
号 | 3-4 |
開始ページ | 128 |
終了ページ | 146 |
抄録 |
The dynamical effects of an asymmetric subduction structure on the generation of plate-like motion were investigated using two-dimensional numerical models of the integrated lithosphere-mantle system. To dynamically generate the plate boundary, we introduce a history-dependent rheology in which the yield strength is determined by past fractures. Only the buoyancy due to the internal density contrast consistently drives convective flow, including the motion of the viscous lithosphere, without imposed boundary conditions. We first investigate the effects of plate yield strength, friction at the plate boundary, and plate age on the emergence of plate-like motion with asymmetric subduction. Plate-like motion is generated when maximum plate strength is as high as that estimated by experimental rheology studies. The reason for this is that asymmetric subduction requires a plate-bending force much less than that for symmetric subduction because the plate gently bends when one-sided subduction occurs. In contrast, the strength of the plate boundary has to be very small for emergence of subduction, as several previous studies on the numerical convection and subduction modeling have pointed out. Development of the subducted slab is also controlled by the age of the plate. In the early stages of subduction, older plates increase their velocities faster because of their larger negative buoyancy. After the slab develops, the plate stiffness, that is, both the yield strength and the plate thickness, control plate velocity so that an older plate subducts more sluggishly. We next explore effects of viscosity layering in the underlying mantle, focusing on the mechanism in which the asthenosphere promotes plate motion. The low viscosity under the lithosphere enhances a mantle drag force that drives the plate, not only concentrating the convective flow beneath the plate but also enlarging its aspect ratio. We also examine longevity of the plate-like motion using the convection models with asymmetric subduction. The asymmetrically s
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著者キーワード |
plate-like motion
mantle convection
asymmetric subduction
yield strength
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NDC分類 |
地球科学・地学・地質学 [ 450 ]
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言語 |
英語
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資源タイプ | 学術雑誌論文 |
出版者 |
Elsevier B.V.
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発行日 | 2008-02 |
権利情報 |
Copyright (c) 2008 Elsevier B.V.
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出版タイプ | Author’s Original(十分な品質であるとして、著者から正式な査読に提出される版) |
アクセス権 | オープンアクセス |
収録物識別子 |
[ISSN] 0031-9201
[DOI] 10.1016/j.pepi.2007.12.004
[NCID] AA00773963
[DOI] http://dx.doi.org/10.1016/j.pepi.2007.12.004
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