Thermal and chemical evolution of the subarc mantle revealed by spinel-hosted melt inclusions in boninite from the Ogasawara (bonin) Archipelago, Japan
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説明
Primitive melt inclusions in chrome spinel from the Ogasawara Archipelago (Japan) compose two discrete groups of high-SiO2, high-MgO (high-Si) and low-SiO2, low-MgO (low-Si) boninitic suites, with ultra-depleted dish- and V-shaped, and less-depleted flat, rare earth element patterns. The most magnesian melt inclusions of each geochemical type were used to estimate the temperature-pressure conditions for primary boninites, which range from 1345 °C at 0.56 GPa to 1421 °C at 0.85 GPa for the 48-46 Ma low-Si and high-Si boninites, and 1381 °C at 0.85 GPa for the 45 Ma low-Si boninite. The onset of the Pacific slab subduction at 52 Ma forced upwelling of depleted mid-oceanic ridge basalt mantle (DMM) to yield proto-arc basalt (PAB). With the rise of DMM, refractory harzburgite ascended without melting. At 48-46 Ma, introduction of slab fluids induced melting of the PAB residue and high-temperature harzburgite, resulting in the low-Si and high-Si boninites, respectively. Meanwhile, convection within the mantle wedge brought the less-depleted residue of PAB and DMM into the region fluxed by slab fluids, which melted to yield the less-depleted low-Si boninite at 45 Ma, and fertile arc basalts, respectively.
収録刊行物
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- Geology
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Geology 43 (2), 151-154, 2015-02-01
Geological Society of America
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詳細情報 詳細情報について
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- CRID
- 1390857291129444480
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- NII論文ID
- 120005593938
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- NII書誌ID
- AA00656697
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- ISSN
- 00917613
- 19432682
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- HANDLE
- 2297/41329
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- 本文言語コード
- en
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- データソース種別
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- JaLC
- IRDB
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