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The Odd Global Topography of Tethys: Large Impact, Tectonics and Resurfacing

Presentation #210.09 in the session Ocean Worlds: Tectonics, Surfaces, and Ionospheres (Oral Presentation)

Published onOct 23, 2023
The Odd Global Topography of Tethys: Large Impact, Tectonics and Resurfacing

An updated global topographic map of Tethys has been completed. The map consists of two components: a photogrammetric (PG) shape model derived from control point radius solutions and a stereogrammetric shape model derived from Cassini stereo images and tied to the PG solution, thus providing a true description of the relief of this body with respect to the triaxial ellipsoid. The new map reveals a dichotomy in which the leading hemisphere is dominated by cratered terrains except for the 400-km and 8-km deep Odysseus basin. An extended zone of small craters has obliterated the normal cratered signature immediately to the east of Odysseus but not to the west, indicating oblique impact. The trailing hemisphere is dominated by Ithaca Chasma but the topography is oddly asymmetric with respect to the trough. To the south it is high standing but not to the north. The high standing flexure rim uplift of Ithaca Chasma identified by others is only present in a small central section being absent in most other sections. This suggests that the strain along the Chasma may be variable from simple extension to shear or shear extension in different sections. Several older highly relaxed basins are identified but these are relatively few suggesting few such basins survived or were formed at all. In the center of the trailing hemisphere are the smooth plains which have a much lower topographic amplitude than any other terrain and which feature several cryptic shallow troughs and several enigmatic sigmoidal depressions and possible embayments to the south. These morphologies compare and contrast with smooth plains on Dione and may be consistent with some form of low viscosity resurfacing or exceptionally high heat flow across resurfaced areas on both bodies.

This work is partially supported by the NASA Planetary Data Archiving and Restoration program.

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