Osmium behavior in a subduction system elucidated from chromian spinel in Bonin island beach sands

Katsuhiko Suzuki, Ryoko Senda, Kenji Shimizu

研究成果: ジャーナルへの寄稿記事

18 引用 (Scopus)

抄録

The Os isotopic system is a potential tracer of a recycled crustal component in mantle or volcanic rocks because of the significant contrast between Os isotope ratios of crust and mantle. However, the potential for crustal contamination overprinting this possible signal has hampered the utility of Os isotopic ratios. We explored the use of Os isotopes in chromian spinel (Cr-spinel) as a discriminator of primitive magma Os compositions in the Izu-Bonin arc, using beach sands as composite samples of the boninite and tholeiite magmas in three different islands. Cr-spinel is an early-stage crystal that preserves its isotopic composition even during later crustal contamination of the bulk rock. We found highly unradiogenic Os isotopic compositions in Cr-spinels from boninites, suggesting that they represent primitive magmas with slight or no Os contribution from the subducting slab during the generation of boninites in the infant arc stage (48-46 Ma). Conversely, the radiogenic Os isotopic ratios in Cr-spinels from tholeiites most likely refl ect the contribution from a slab-derived component, because more oxidative conditions in the subarc mantle probably allowed Os to mobilize from the subducting slab during the transitional arc stage (45-41 Ma). Although shallow-level assimilation of crustal components with radiogenic Os may overprint the original Os signature of tholeiite magma during its ascent, Cr-spinel allows us to compensate such possibilities.

元の言語英語
ページ(範囲)999-1002
ページ数4
ジャーナルGeology
39
発行部数11
DOI
出版物ステータス出版済み - 11 1 2011

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osmium
spinel
slab
beach
subduction
tholeiite
crustal contamination
mantle
isotopic ratio
sand
isotopic composition
magma
isotope
boninite
overprinting
volcanic rock
tracer
crystal
crust
rock

All Science Journal Classification (ASJC) codes

  • Geology

これを引用

Osmium behavior in a subduction system elucidated from chromian spinel in Bonin island beach sands. / Suzuki, Katsuhiko; Senda, Ryoko; Shimizu, Kenji.

:: Geology, 巻 39, 番号 11, 01.11.2011, p. 999-1002.

研究成果: ジャーナルへの寄稿記事

Suzuki, Katsuhiko ; Senda, Ryoko ; Shimizu, Kenji. / Osmium behavior in a subduction system elucidated from chromian spinel in Bonin island beach sands. :: Geology. 2011 ; 巻 39, 番号 11. pp. 999-1002.
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