著者

Naoki HIRAKAWA Yoko KEBUKAWA Takazo SHIBUYA Hisahiro UEDA Kensei KOBAYASHI

出版者

Japan Association of Mineralogical Sciences

雑誌

Journal of Mineralogical and Petrological Sciences (ISSN:13456296)

巻号頁・発行日

vol.118, no.1, pp.220913, 2023 (Released:2023-07-26)

参考文献数

53

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Several investigations have demonstrated that olivine may be used to simulate geochemical and cosmochemical reactions. Since olivine in extra-terrestrial samples has varying forsterite numbers and natural olivine contains inevitable impurities, synthetic olivine with the requisite forsterite number has been prepared for various experimental research. This study aimed to synthesize Fe-bearing olivine via synthetic experiments conducted at near-solidus temperatures and elucidate the formation and decomposition mechanisms of the obtained Fe-bearing olivine. Specifically, we attempted to synthesize Fo60 [Forsterite number = 100 × Mg/(Mg + Fe) = 60] olivine using a mixture of analytical-grade SiO2, MgO, and Fe2O3. To clarify the stability of the obtained olivine, the temperature range (1350-1500 °C) and heating durations (1.5 or 15 h) were controlled under a constant oxygen fugacity of QFM-1 log units.The target olivine (Fo60) was obtained via heating for 1.5 h at 1500 °C, corresponding to the solidus line temperature. However, maintaining the olivine obtained at this temperature for 15 h resulted in a much higher forsterite number owing to the formation of oxidized minerals of olivine (magnetite and pyroxene). Similar oxidation products were also obtained following heating at 1450 °C for 15 h. These results indicated the primary formation of Fe-bearing olivine during 1.5 h of heating and its subsequent decomposition to magnetite and pyroxene owing to the high-temperature oxidation at near-solidus temperatures during heating for 1.5-15 h. These findings highlight a strategy for synthesizing Fe-bearing olivine and the associated mechanism and provide experimental insights into the decomposition of olivine in natural igneous rocks.

著者

Yuto MOGI Yoko KEBUKAWA Kensei KOBAYASHI

出版者

The Japan Society for Analytical Chemistry

雑誌

Analytical Sciences (ISSN:09106340)

巻号頁・発行日

pp.21P188, (Released:2021-08-13)

被引用文献数

2

著者

Walaa Elmasry Yoko Kebukawa Kensei Kobayashi

雑誌

JpGU-AGU Joint Meeting 2020

巻号頁・発行日

2020-03-13

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Extraterrestrial delivery of organic compounds including amino acids to the early Earth during the late heavy bombardment (3.8-4.5 billion years ago) may have been important for the origin of life. Recently, it is suggested that chondritic organic matter was produced through reactions of interstellar formaldehyde, followed by condensation, and carbonization probably during hydrothermal alteration on chondritic asteroids (Cody et al 2011). Furthermore, Kebukawa et al. (2013, 2015) illustrated that the presence of ammonia significantly enhances the yields of IOM from formaldehyde via formose reaction at 150 °C, producing amino acids. Meteorites serve as delivery systems for extraterrestrial phyllosilicate minerals to Earth. Phyllosilicates may act as absorbents and catalysts for the reactions of organic precursor molecules in the early solar system (Pearson et.al 2002). In the current research, we are studying formations of amino acid at 150 °C and reveal the expected role of minerals, namely, montmorillonite, olivine and serpentine for amino acid productions in water-bearing planetesimals.We synthesized organic compounds using a mixture of water, formaldehyde and ammonia (H2O, H2CO, NH3) in a ratio of 100:7:1 with adding minerals (10 g/ L) by simulating primordial materials in comets and asteroids. Aqueous solutions were heated at 150 °C for 24, and 72 hours. The resulted products were divided into two parts, the first part analyzed using a FT/IR, and GFC, while the other one was acid hydrolyzed, desalted, and subjected to amino acid analysis using an HPLC.In HPLC analysis, considerable amounts of various amino acids including glycine and alanine were detected. Moreover, presence of non-protein amino acids (β-Ala, γ-ABA) is considered as an evidence for extraterrestrial origin and against terrestrial contamination. Our preliminary results showed that the obtained amount of amino acids was elevated with the presence of minerals. FT/IR spectra of samples with minerals showed more spectral intensities than samples without minerals due to synthesis of more organic compounds. GFC showed that high molecular weight organic compounds were formed which may be characterized as amino acid precursors that maintain stable at high temperature and longer durations giving various kinds of amino acids after acid hydrolysis. These results suggested that various amino acids could be formed abiotically via a mixture of formaldehyde, ammonia, and water, as well as, the associated minerals act as catalysts to produce amino acid precursors during aqueous activities in the planetesimals.References:Cody, G. D. et al. PNAS 108, 19171–19176 (2011).Kebukawa, Y., David Kilcoyne, A. L. & Cody, G. D. The Astrophysical Journal 771, 19 (2013).Kebukawa, Y. & Cody, G. D. Icarus 248, 412–423 (2015).Pearson, V. K. Meteoritics & Planetary Science 37, 1829–1833 (2002).