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http://hdl.handle.net/20.500.12386/27353
Titolo: | Laboratory experiments on ammoniated clay minerals with relevance for asteroid (1) Ceres | Autori: | DE ANGELIS, Simone STEFANI, STEFANIA DE SANCTIS, MARIA CRISTINA PICCIONI, GIUSEPPE AMMANNITO, ELEONORA |
Data pubblicazione: | 2017 | Titolo del volume in cui è pubblicato il poster: | EGU General Assembly Conference Abstracts | Serie: | GEOPHYSICAL RESEARCH ABSTRACTS | Da pagina:: | 7962 | Abstract: | Recent observations with VIR spectrometer onboard Dawn spacecraft [1] have suggested the presence of ammoniated phyllosilicates widespread on the surface of asteroid (1) Ceres [2,3]. The global surface composition of Ceres as suggested by VIR average infrared spectrum in the 1-4 micron range appears to be due to a mixture of NH4-bearing phyllosilicates, serpentine, carbonates and a dark absorbing phase (magnetite or amorphous carbon) [2]. An absorption feature occurring near 3.1 micron in the average spectrum is considered the main evidence for the presence of NH4-bearing phase; nevertheless in the past several authors tried to explain this feature, as observed with telescopic spectra, invoking the presence of brucite, cronstedtite, water ice or clays [4]. In this project we are carrying out laboratory experiments with the aim of studying ammoniated phyllosilicates in the visible-infrared range. A suite of 9 clay minerals has been used for this study, including illite, nontronite and montmorillonite. In order to produce the ammoniated species we followed a modified procedure based on the one described in Bishop et al. (2002) [5]. All minerals were reduced in fine grain size (<36 micron), treated with ammonium hydroxide (NH4OH) and heated in oven at 200°C for 24 h at normal pressure conditions, before the measurements. Reflectance spectra were acquired with the Fourier Transform Infrared Spectrometer (FTIR) in use at INAF-IAPS/P-LAB, in the range 1-14 μm, on both clay minerals and NH4-treated clays. Almost all spectra of NH4-treated species are characterized by the occurrence of several new absorption features, appearing at different wavelengths near 2, 3, 6 and 7 micron. In some cases the spectral shape of already existent absorption bands resulted deeply modified. A few species did not show the appearance of new features. These results suggest that NH4+ ions fix in various ways in different minerals. Nontronite and montmorillonite appear to be the best candidates, among the studied suite, to be used in future laboratory reproduced analog mixtures. [1] Russell C.T. et al., 2004, Planetary and Space Science, 52, 465-489 [2] De Sanctis M.C. et al., 2015, Nature, 528, 241-244 [3] Ammannito E. et al., 2016, Science, vol.353, issue 6303 [4] Rivkin A.S. et al., 2011, Space Science Reviews, 163, 95-116 [5] Bishop J.L. et al., 2002, Planetary and Space Science, 50, 11-19 | Titolo del convegno: | EGU General Assembly 2017 | Luogo del convegno: | Vienna, Austria | Periodo del convegno: | 23–28 April, 2017 | URI: | http://hdl.handle.net/20.500.12386/27353 | URL: | https://www.egu2017.eu/ | ISSN: | 1029-7006 | Bibcode ADS: | 2017EGUGA..19.7962D | Fulltext: | open |
È visualizzato nelle collezioni: | 3.02 Abstract in Atti di convegno |
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