The amount of recycled crust in sources of mantle-derived melts.
Plate tectonic processes introduce basaltic crust (as eclogite) into the peridotitic mantle. The proportions of these two sources in mantle melts are poorly understood. Silica-rich melts formed from eclogite react with peridotite, converting it to olivine-free pyroxenite. Partial melts of this hybrid pyroxenite are higher in nickel and silicon but poorer in manganese, calcium, and magnesium than melts of peridotite. Olivine phenocrysts' compositions record these differences and were used to quantify the contributions of pyroxenite-derived melts in mid-ocean ridge basalts (10 to 30%), ocean island and continental basalts (many >60%), and komatiites (20 to 30%). These results imply involvement of 2 to 20% (up to 28%) of recycled crust in mantle melting.
Sobolev
Alexander V
AV
Max Planck Institute (MPI) for Chemistry, Post Office Box 3060, 55020 Mainz, Germany. sobolev@geokhi.ru
Hofmann
Albrecht W
AW
Kuzmin
Dmitry V
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Yaxley
Gregory M
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Arndt
Nicholas T
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Chung
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Danyushevsky
Leonid V
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Elliott
Tim
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Frey
Frederick A
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Garcia
Michael O
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Gurenko
Andrey A
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Kamenetsky
Vadim S
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Kerr
Andrew C
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Krivolutskaya
Nadezhda A
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Matvienkov
Vladimir V
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Nikogosian
Igor K
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Rocholl
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Sigurdsson
Ingvar A
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Sushchevskaya
Nadezhda M
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Teklay
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