Cryptic striations in the upper mantle revealed by hafnium isotopes in southeast Indian ridge basalts
The Earth's mantle is isotopically heterogeneous on length scales ranging from centimetres to more than 104 kilometres. This heterogeneity originates from partial melt extraction and plate tectonic recycling, whereas stirring during mantle convection tends to reduce it. Here we show that mid-oc...
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Published in | Nature Vol. 440; no. 7081; pp. 199 - 202 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
London
Nature Publishing Group
09.03.2006
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Subjects | |
Online Access | Get full text |
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Summary: | The Earth's mantle is isotopically heterogeneous on length scales ranging from centimetres to more than 104 kilometres. This heterogeneity originates from partial melt extraction and plate tectonic recycling, whereas stirring during mantle convection tends to reduce it. Here we show that mid-ocean ridge basalts from 2,000 km along the southeast Indian ridge (SEIR) display a bimodal hafnium isotopic distribution. This bimodality reveals the presence of ancient compositional striations (streaks) in the Indian Ocean upper mantle. The number density of the streaks is described by a Poisson distribution, with an average thickness of ∼40 km. Such a distribution is anticipated for a well-stirred upper mantle, in which heterogeneity is continually introduced by plate tectonic recycling, and redistributed by viscous stretching and convective refolding. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 ObjectType-Article-2 ObjectType-Feature-1 |
ISSN: | 0028-0836 1476-4687 1476-4679 |
DOI: | 10.1038/nature04582 |