Geological Society of America

T146 Friends of Hoth: Episode II—Icy Bodies of the Solar System

Monday, 23 October 2017
1:30 PM - 5:30 PM
Tahoma 1

CERES’ NEAR SURFACE PROPERTIES FROM LANDSLIDES

Paper number: T146-6
Program: Technical Sessions
Time: 2:45 PM – 3:00 PM

Authors

Heather Chilton Presenting Author
Georgia Institute of Technology, Atlanta, GA
Christopher T. Russell
University of California, Los Angeles, CA
Carol A. Raymond
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA
James Wray
Georgia Institute of Technology, Atlanta, GA
Britney E. Schmidt
Georgia Institute of Technology, Atlanta, GA
Ken L. Ferrier
Georgia Institute of Technology, Atlanta, GA
Kayla Duarte
Georgia Institute of Technology, Atlanta, GA
Kynan H.G. Hughson
Georgia Institute of Tecjnology, Atlanta, GA
Jennifer Scully
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA
Hanna Sizemore
Planetary Science Institute, Tucson, AZ
A. Nathues
Max-Planck Institute for Solar System Research, Katlenburg-Lindau
Thomas Platz
Max Planck Institute for Solar System Research, Göttingen

Abstract

Dwarf planet Ceres shows evidence of several geological processes that are consistent with subsurface ice. One of these processes is landsliding, which is revealed by observations of large (5 – 20 km long) landslides in imagery from the orbiting Dawn spacecraft. We build on our prior work on Cerean landslides, in which we classified flows by morphology into three types (T1, T2, and T3), to improve constraints on the properties and structure of the top few kilometers below the surface. We focus on a more restricted group of T1 and T2 features that conform to morphological descriptions: T1 landslides lie along steep slopes and have a thick, rounded, and steep toe, while T2 landslides are thin and cover shallow slopes. Aside from this subset of Cerean landslides, there are intermediate landslides and the T3 landslides, which have been more closely associated with ejecta.

We estimated effective coefficients of friction using the ratio of landslide drop height to runout length (H/L), using the landslides’ maximum heights and lengths as well as from their center of mass. Using both methods, Ceres’ landslides possess H/L ratios that imply lower friction coefficients than for typical rock or saturated clays, consistent with the idea that subsurface ice enhanced their mobility. Landslide scar volume-area relationships for T1 landslides are consistent with terrestrial bedrock landslides, while those for T2 landslides are consistent with shallower failures.

Adjusting water equivalent hydrogen estimations of near-surface ice by removing hydrogen taken up by clay-bearing surface materials still results in 10-15% and 25-30% ice in the upper meter of surface material at the equator and poles, respectively. Taken together, this is consistent with an ice-depleted layer of clays and other materials, containing only interstitial ice or ice lenses, which is thickest at low latitudes and thins towards the poles. Below this layer is a comparatively ice-rich layer, which is present at or near the surface above 70° latitude, where increased ice content and decreased temperature allow stronger, more pervasive cementation.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-306026

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