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Abstract

The geology of the outstanding crater Occator on Ceres has been studied by combining highest resolution color images and other information from the DAWN mission. Thus, surface and sub-surface layers and geologic processes can be understood and interpreted in a consistent manner. In order to achieve this, morphometry, absolute surface unit ages, color, and the distribution of foci of activity were the key data. These data show that the ascent of brine from reservoir(s) at depth and deposition of its salts on the surface persisted much longer than initially thought possible as an immediate result of the primary impact. The youngest depositional processes of bright material occurred less than 2 Ma ago. Also, the bright Cerealia and Vinalia Faculae are not the only traces of this activity; updoming is present on the southwestern crater floor. Faculae coincide with fractures and vents and indicate complex mechanisms of the deposition of bright carbonate-rich material. Due to the large age difference between the Occator impact itself, modeled cooling times of heated crater material, and the recent activity at the faculae we conclude that endogenic forces were lately acting. The distribution and thickness of surface and sub-surface brine layers are far from homogeneous in the upper crust beneath Occator. Further evidence regarding the distribution of materials has been derived from the distribution of the ejecta and the transition of ejecta to background material outside the crater.