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ID 27713
本文ファイル
著者
Suyama, Yuka
Ando, Jun-ichi
Komiya, Tsuyoshi
キーワード
Mantle xenolith
Deformation
Mantle metasomatism
Cratonic lithosphere
NDC
化学
抄録(英)
Mantle xenoliths from Kimberley, South Africa, contain texturally distinct peridotites; coarse granular to extensively sheared peridotites. Mineral chemistries of the textually distinct peridotite xenoliths indicate that these mantle rocks were equilibrated at similar P-T conditions: 44-54 kbar and 970-1130 degrees C for granular peridotites, and 41-50 kbar and 950-1080 degrees C for sheared periclotites. The Kimberley periclotites showing various deformation textures are restricted to a relatively narrow depth range (120-160 km). They display no systematic correlation between texture and estimated equilibrium pressure and temperature, whereas sheared periclotites in the Lesotho kimberlites commonly originated from greater depths and higher temperature. The large local variations in the degree of deformation in the cratonic lithosphere beneath Kimberley require pronounced weakening due to localized high water flux that can be associated with mantle metasomatism. Sheared periclotites have more depleted compositions in FeO and CaO compositions than those of granular periclotites, but have a higher orthopyroxene modal abundance and contain sodium-rich clinopyroxene, which are consistent with that extensive deformations associated with Si-rich fluid/melt metasomatism. We therefore conclude that mantle metasomatism has an important role in facilitating deformation locally within the cratonic lithosphere. and is responsible for the textural variations of peridotite xenoliths from the cratonic roots.
掲載誌名
Lithos
109巻
3-4号
開始ページ
333
終了ページ
340
出版年月日
2009
出版者
Elsevier Science BV
ISSN
0024-4937
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
Copyright (c) 2008 Elsevier B.V.
関連情報URL
部局名
理学研究科