このエントリーをはてなブックマークに追加
ID 28631
本文ファイル
著者
Yoshida, Masaki
キーワード
mantle convection
numerical calculation
subducting slab
plate margin
viscosity
geoid anomaly
NDC
地球科学・地学・地質学
抄録(英)
Instantaneous flow numerical calculations in a three-dimensional spherical shell are employed to investigate the effects of lateral viscosity variations (LVVs) in the lithosphere and mantle on the long-wavelength geoid anomaly. The density anomaly model employed is a combination of seismic tomography and subducting slab models based on seismicity. The global strain-rate model is used to represent weak (low-viscosity) plate margins in the lithosphere. LVVs in the mantle are represented on the basis of the relation between seismic velocity and temperature (i.e., temperature-dependent rheology). When highly viscous slabs in the upper mantle are considered, the observed positive geoid anomaly over subduction zones can be accounted for only when the viscosity contrast between the reference upper mantle and the lower mantle is approximately 103 or lower, and weak plate margins are imposed on the lithosphere. LVVs in the lower mantle exert a large influence on the geoid pattern. The calculated geoid anomalies over subduction zones exhibit generally positive patterns with quite high amplitudes compared with observations, even when the low activation enthalpy of perovskite in the lower mantle is employed. Inferred weak slabs in the lower mantle may be explained in terms of recent mineral physics results, highlighting the possibility of grain-size reduction due to the postspinel phase transition.
掲載誌名
Physics of the Earth and Planetary Interiors
172巻
3-4号
開始ページ
278
終了ページ
288
出版年月日
2009-02
出版者
Elsevier B.V.
ISSN
0031-9201
NCID
出版者DOI
言語
英語
NII資源タイプ
学術雑誌論文
広大資料タイプ
学術雑誌論文
DCMIタイプ
text
フォーマット
application/pdf
著者版フラグ
author
権利情報
(c) 2008 Elsevier B.V. All rights reserved.
関連情報URL(IsVersionOf)
http://dx.doi.org/10.1016/j.pepi.2008.10.018
部局名
理学研究科