Diffusivities of Rare Earth Elements and Ba in Magmatic Silicate Melts at High Pressures

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概要

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• Diffusivities of 11 rare earth elements (REE) and Ba in jadeite (NaAlSi2O6) and diopside (CaMgSi2O6) melts have been measured at pressures between 10 and 20kbar. In jadeite melt, diffusivities of REE increase regularly with increasing their ionic radii, light REE (e.g., La and Ce) diffuse faster than heavy REE (e.g., Yb and Lu) by about 30%, Eu diffuses faster by factor of 8 to 12 than other REE under reducing conditions, and diffusivities of REE increase with increasing pressure at constant temperature. In diopside melt, diffusivities of REE are nearly the same as that of Ca and decrease with increasing pressure. The present study demonstrates that diffusion process in magma should change the relative abundances of REE and also generate Eu anomalies without involvement of plagioclase feldspar. This diffusion-induced process is a newly recognized mechanism of changing the relative REE abundances in magmas and generating Eu anomalies, and it must be taken into account in interpreting the REE abundance patterns of igneous rocks.

• 日本学士院の論文

著者

• Nakamura Eizo

  Institute Of Mineralogy Petrology And Economic Geology Tohoku University

• KUSHIRO Ikuo

  Institute for Study of the Earths Interior, Okayama University

• KUSHIRO Ikuo

  Institute for Study of the Earth's Interior, Okayama University

• Nakamura Eizo

  Institute for Study of the Earth's Interior, Okayama University

関連論文

• A New Finding of Alkaline Rocks in the Palaeogene Tertiary of the Inner Side of Southwest Japan and its Geological Significances
• Diffusivities of Rare Earth Elements and Ba in Magmatic Silicate Melts at High Pressures
• Lead Isotope Analyses of Standard Rock Samples
• Precise Lithium Isotopic Analysis by Thermal Ionization Mass Spectrometry Using Lithium Phosphate as an Ion Source Material.
• Interaction between Subducted Oceanic Slab and Wedge Mantle Inferred from Across-arc Variations of Pb, Sr and Nd Isotopic Compositions in Northeastern Japan.

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