窒素・炭素の親鉄性に関する実験的研究 : 地球コア中の軽元素の定量をめざして

概要

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Nitrogen and carbon partition experiments between metallic iron and silicate melt under high pressure were carried out in order to quantitatively evaluate the siderophile behavior of these elements. Under a pressure of 2 GPa, we obtained partition coefficients (concentrations in metal over those of silicate glass) of l.5-8.7 for nitrogen and 44-108 for carbon. We expect a lower C/N ratio in the present Earth's mantle than the initial ratio, if we assume that nitrogen and carbon were partitioned into Earth's core and mantle in a proportion determined by our experiments. However, the C/N ratios observed among MORB samples suggest that the present upper mantle possesses a rather high C/N ratio. Presently the reason for the nitrogen depletion, or the carbon excess, in the mantle is not clear. More reliable partition experiments at 2 GPa and higher pressure region are required.
特定非営利活動法人日本火山学会の論文
1997-04-25