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Ammoniation of Phyllosilicates, Carbonaceous Chondrite Meteorites, and Implications for the Nature of Ammoniated Materials on Ceres

Ehlmann, B. L. and Hodyss, R. and Ammannito, E. and Rossman, G. R. and De Sanctis, M. C. and Raymond, C. A. (2017) Ammoniation of Phyllosilicates, Carbonaceous Chondrite Meteorites, and Implications for the Nature of Ammoniated Materials on Ceres. In: 48th Lunar and Planetary Science Conference, March 20-24, 2017, The Woodlands, TX.

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Ammonciated- and phyllosilicatebearing materials were discovered on Ceres and globally mapped with the VIR imaging spectrometer on the Dawn mission [1-3]. Key Ceres infrared spectral features are located at ~3.05 µm, indicating NH4-bearing materials, and 2.72 µm, indicating Mg-OH-bearing materials. Their co-occurrence everywhere on the surface [3] makes it likely, but not certain, that Mg phyllosilicates are the carrier of the ammonium. Readily available spectral libraries have ammoniated, Al-phyllosilicates, which have been used in radiative transfer unmixing models to estimate the composition of the Ceres surfaces [2]. Yet, more suitable may be Fe- or Mg-phyllosilicates, which are more likely from meteoritic materials. Here, we obtain, purify, and ammoniate a variety of Ceres-relevant analog materials, including both phyllosilicates and meteorites. We then evaluate (i) which phases ammoniate; (ii) which ammoniated phases exhibit absorptions with similar positions, widths, and shapes to those observed for Ceres; and (iii) if/how the NH4-related absorptions change at different temperatures under vacuum [detailed further in 4]. The overarching goals are to refine the identification of the ammoniated species on Ceres and develop a spectral library suitable for accurate, quantitative radiative transfer models that estimate Ceres’ composition.

Item Type:Conference or Workshop Item (Paper)
Related URLs:
URLURL TypeDescription paper LPSC Conference
Ehlmann, B. L.0000-0002-2745-3240
Hodyss, R.0000-0002-6523-3660
Ammannito, E.0000-0001-6671-2690
Rossman, G. R.0000-0002-4571-6884
De Sanctis, M. C.0000-0002-3463-4437
Raymond, C. A.0000-0002-4213-8097
Group:Division of Geological and Planetary Sciences
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LPI Contribution1964
Record Number:CaltechAUTHORS:20170623-180944022
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:78567
Deposited By: Gail Peretsman Clement
Deposited On:09 Mar 2020 14:56
Last Modified:22 Nov 2022 21:05

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