Distribution of phyllosilicates on the surface of Ceres

• DOI: 10.1126/science.aaf4279
• Publication Date: 2016-09-01T18:54:29Z
• Authors: E. Ammannito; M. C. DeSanctis; M. Ciarniello; A. Frigeri; F. G. Carrozzo; J.-Ph. Combe; B. L. Ehlmann; S. Marchi; H. Y. McSween; A. Raponi; M. J. Toplis; F. Tosi; J. C. Castillo-Rogez; F. Capaccioni; M. T. Capria; S. Fonte; M. Giardino; R. Jaumann; A. Longobardo; S. P. Joy; G. Magni; T. B. McCord; L. A. McFadden; E. Palomba; C. M. Pieters; C. A. Polanskey; M. D. Rayman; C. A. Raymond; P. M. Schenk; F. Zambon; C. T. Russell
• Keywords: Dwarf planet

INTRODUCTION The surface of the dwarf planet Ceres is known to host phyllosilicate minerals, but their distribution and origin have not previously been determined. Phyllosilicates are hydrated silicates, presence on intriguing given that structure evolves through an aqueous alteration process. In addition, some phyllosilicates bear NH 4 , which places a constraint pH redox conditions during evolution Ceres. We studied across planet’s better understand evolutionary pathway RATIONALE Using data acquired by mapping spectrometer (VIR) onboard Dawn spacecraft, we mapped spatial different minerals basis diagnostic absorption features in visible infrared spectra. OH-stretch fundamental at about 2.7 µm 3.1 µm. From our composition maps, infer materials identified. RESULTS found Mg- -bearing ubiquitous chemical fairly uniform. widespread these two types strong indication global extensive alteration—i.e., water point Ceres’ geological history. Although detected compositionally homogeneous, variations intensity 3-µm region reflectance spectrum. Such likely due variability relative mineral abundance (see figure). CONCLUSION large-scale regional evident figure suggest lateral heterogeneity surficial scales several hundreds kilometers. Terrains associated with Kerwan crater (higher concentration phyllosilicates) appear smooth, whereas Yalode (lower characterized both smooth rugged terrains. These distinct morphologies concentrations observed craters similar size may reflect compositions and/or rheological properties. On top this heterogeneity, small-scale individual could result from proportions mixed stratified upper crustal layer has exposed impacts. Variations fresh craters, such as 34-km-diameter Haulani, indicate over vertical scale few kilometers, much larger 126-km-diameter Dantu, stratification extend for least tens Abundance maps. Qualitative maps abundances ( ) bottom based depth features. pattern, although they differ localized regions Urvara. bar valid equator.