Li isotope geochemistry ofHawaiian plume
| Project/Area Number |
18540475
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Petrology/Mineralogy/Science of ore deposit
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| Research Institution | Okayama University |
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Principal Investigator |
MORIGUTI Takuya Okayama University, Institute for the Study of Earth Interior, Associate Professor (70304342)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAMAURA Eizo OKAYAMA UNIVERSITY, Institute for the Study of Earth Interior, Professor (80201672)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,950,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥450,000)
Fiscal Year 2007: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
Fiscal Year 2006: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | glass inclusion / Ithium isotope / Hawaiian basaltic rocks / olivine / dformation structure / isotopic fractionation / ハワイ / プリューム / 転位 |
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| Research Abstract |
It has been suggested that the chemical composition of glass inclusion included in olivine from basaltic rocks represent the primary chemical compositions of the melt. It has been expected that, therefore, the data of the melt inclusion bring useful information for the understanding of the chemical heterogeneity and evolution of mantle. In order to assess that the lithium isotopic composition preserved in glass inclusion in olivine reflect the primary melt composition and to evaluate lithium isotope as a geochemical tracer to understand the mantle heterogeneity, in this study, lithium isotopic compositions of glass inclusions in olivine from Hawaiian and Icelandic basaltic rocks together with host olivines were measured by SIMS.
In order to homogenize glass inclusion in olivine from Hawaiian basalts, heating processes are necessary as an pretreatment because mineral inclusions formed in cooling condition are included in the glass inclusion. After rehomogenization processes, heterogeneit
… More
y observed in lithium isotopic composition in glass inclusion whose size is larger than 100 pm. We suggested that the following three possibilities to explain the heterogeneity: (1) During rehomogenization processes, lithium included in glass inclusion is evaporated, resulting that large isotopic fractionation occur. (2) After trap of melt as inclusion in olivine host, lithium was diffusive out from glass inclusion to the surrounding host olivine. (3) There was originally submicron scale heterogeneity in melts before it was trapped as melts. In order to evaluate these possibilities, lithium isotope analyses were undertaken for glass inclusions in olivine from Icelandic basalts. Rehomogenization treatment is not necessary for the Icelandic samples because melt inclusions are not included in the glass inclusions. The results indicate that the heterogeneity was observed in lithium isotopic composition of the glass inclusion. If the bubble is included in the glass inclusion, lithium isotopic compositions were changed systematically. That is, δ^7Li was increased as it approaches the bubble. This indicates that ^6Li was transferred to the bubble faster than ^7Li. Therefore, observed heterogeneity can be caused by foaming in magma chamber and/or rehomogenization treatment, resulting that primary lithium isotopic composition cannot be preserved in glass inclusions.
In addition, lithium isotopic compositions of the host olivine were measured by SIMS. Extraordinary high δ^7Li (+120 permil) were obtained in deformed olivine. At high temperature condition, such extraordinary high δ^7Li values cannot be produced by isotopic fractionation under equilibrium condition. Therefore, this anomaly observed in the isotopic composition may not show original composition but reflect kinetic effect during deformation processes in olivine at lithospheric mantle conditions. Less
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Report
(3 results)
Research Products
(20 results)
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[Journal Article] Lithium isotopic systematics of peridotite xenoliths from Hannuoba, North China Craton : Implications for melt-rock interaction in the considerably thinned lithospheric mantle2007
Author(s)
Tang, Y-J., Zhang, H-F., Nakamura, E., Moriguti, T., Kobayashi, K., Ying, J-F
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Journal Title
Geochimica et Cosmochimica Acta 71
Pages: 4327-4341
Description
「研究成果報告書概要(欧文)」より
Related Report
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[Journal Article] Boron and lead isotope signatures of subduction-zone m?lange formation : Hybridization and fractionation along the slab-mantle interface beneath volcanic arcs2007
Author(s)
King, R. L., Bebout, G., E., Grove, M., Moriguti, T., Nakamura, E
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Journal Title
Chemical Geology 239
Pages: 305-322
Description
「研究成果報告書概要(欧文)」より
Related Report
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[Journal Article] Large-scale fluid flow in a cold subduction-zone : SIMS Li-isotope study of jadeitite veins in Franciscan metagraywacke2007
Author(s)
Tsujimori, T., Morieuti, T., Kunihiro, T., Kobayashi, K., Nakamura, E
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Journal Title
Geochimica et Cosmochimica Acta 71, A1040
Description
「研究成果報告書概要(欧文)」より
Related Report
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[Presentation] Lithium in melt inclusions records crustal assimilation at Volcan Jorullo, Mexico2007
Author(s)
Feineman, M. D., Johnson, E., Wallace, P., Kobayashi, K., Moriguti, T., Nakamura, E., and Rubin. K.
Organizer
American Geophysical Union, Fall Meeting
Place of Presentation
サンフランシスコ
Description
「研究成果報告書概要(和文)」より
Related Report
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[Presentation] Lithium in melt inclusions records crustal assimilation at Volcan Jorullo, Mexico2007
Author(s)
Feineman, M., D., Johnson, E., Wallace, P., Kobayashi, K., Morieuti T., Nakamura, E., Rubin, K
Organizer
American Geophysical Union, Fall Meeting
Place of Presentation
San Francisco
Description
「研究成果報告書概要(欧文)」より
Related Report
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