T144 The Big Picture from Small Bodies: Dwarf Planets, Asteroids, and Comets

Monday, 23 September 2019
1:30 PM - 5:30 PM
Room 232BC, North Building

FROST HEAVES MAY EXIST IN OCCATOR CRATER, CERES!

Paper number: T144-7
Program: Technical Sessions
Time: 2:55 PM – 3:10 PM

Authors

Abstract

The ~90 km in diameter Occator crater is one of the youngest and most prominent geologic structures on the surface of Ceres. Home to the largest of Ceres’ infamous bright sodium carbonate deposits (faculae), Occator was extensively imaged during the final extended mission of the Dawn spacecraft. During periapsis of this final orbit, Dawn reached altitudes as low as ~35 km above the surface, and spatial image resolutions up to ~3 m/pixel [1]. These images revealed a panoply of surface features, from tens of meters to kilometers in scale, with morphologies suggestive of ground ice or ground water origins, such as: quasi-polygonal hills, a myriad of small mounds, sinuous ridges, extensional fractures, small central pit craters, “ring mold craters”, salt deposits, and candidate pingos.

We examined the entirety of Occator crater at a scale of 1:10,000 and identified over 900 positive relief features, primarily small mounds, whose origins may be related to ground ice and hydrological processes. We test this hypothesis by systematically categorizing these features based upon appearance and morphology, evaluating their geologic distribution and stratigraphic relationships, and through comparative planetology with other complex craters, crater induced hydrothermal systems, and periglacial environments. Furthermore, we investigate the plausibility of pingo and frost heave formation from an impact induced brine reservoir using a simple, physics based, numerical model.

Initial results suggest that potential small-scale frost heaves within Occator have a strong affinity for the lobate floor deposits, particularly those found in the southern and eastern portion of the crater, which have been interpreted to have been deposited as a flowing slurry of impact melted debris [2]. Larger hundred-meter scale mounds, which bear the most resemblance to terrestrial pingos, typically form in clusters and are associated with smaller conical mounds and extensional fractures indicating a potential correlation with areas of high hydraulic conductivity.

Further investigation of potential frost heaves in Occator is vital for our understanding of the hydrological evolution of large craters on Ceres and other icy worlds.

References:

[1] Schenk et al. (2019) LPSC L, Abs. #2828

[2] Scully et al. (2019) Icarus 320, 7-23

Geological Society of America Abstracts with Programs. Vol. 51, No. 5

doi: 10.1130/abs/2019AM-338567

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