162-13 Progress on Global Geologic Mapping of Tethys

Session: Planetary Geologic Mapping Across the Solar System

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Abstract:

We provide an update on progress to produce a US Geological Survey Scientific Investigations Map of Saturn’s moon Tethys at 1:5M scale. Tethys, which features tectonism, potential cryovolcanic resurfacing, and very differential relaxation states of large impact features, belongs to an important class of mid-sized saturnian satellites that display evidence for endogenic activity that is intermediate between the heavily cratered saturnian satellites and the highly active Enceladus. This class is vital to understanding how icy worlds become ocean worlds or not. 

Mapping has progressed using the publicly available global mosaic of Tethys generated in April 2014, which has been supplemented with five additional Cassini mosaics that were obtained after that date, in addition to a global stereo digital elevation model and color mosaic. To date, we have completed mapping of linear features across Tethys. These include its extensional tectonics (almost entirely contained within Ithaca Chasma that is aligned along a great circle extending ~75% around the globe), crater chains, and reddish lineaments, the latter concentrated in the northern hemisphere and showing a spatial pattern that is centered on the current tidal axis with Saturn. We are currently mapping impact craters across Tethys, the largest of which is the young, ~450 km diameter Odysseus impact basin, the ejecta blanket from which has obscured the topography of large (tens of km diameter) impact craters out to ~350 km from its rim. The basin features an unusual central complex with a 2-4 km deep central pit surrounded by massifs elevated by 6-9 km above the basin floor. Besides mapping craters within the geologic map itself, we are also in the process of assembling a global database of craters larger than 4 km in diameter. This will be used to generate a spatial crater density map that will aid in tracing the contacts of regional geologic units, including Odysseus ejecta and the smooth and lightly cratered plains that occupy Tethys’ trailing hemisphere, which are potential evidence for cryovolcanic resurfacing. This database will be used to assign absolute model ages to our mapped units, and will also be used to thoroughly assess superposition relations where craters overlap with tectonic features, which will help with constraining the timing of Ithaca Chasma’s formation.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-7976

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