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Tectonics on Pluto’s moon Charon

On May 1st 2017, Icarus journal published a special issue focusing on science results of the New Horizons flyby of the Pluto system in July 2015. Several Ames-based researchers have published first-author studies within this issue.

One such study is the investigation of the variety of extensional tectonic features that are a defining characteristic of the surface of Pluto’s moon Charon, authored by Ross Beyer. New Horizons images have revealed that a variety of terrains show extensional tectonism on Charon, which displays surprisingly high surface relief (>10 km) for a relatively small world (radius of 606 km). However, there is no evidence for compressional or strike-slip faulting on Charon. The study performed mapping of tectonic features on Charon’s encounter hemisphere (see attached figure, which includes the mapped features superimposed on an underlying New Horizons mosaic of the surface, as well as in isolation). The surface of Charon is considerably more tectonically deformed than that of Pluto, both in terms of the widths and reliefs of the fractures concerned, and their areal coverage relative to the parent body.  The most prominent tectonism is in the form of a belt of very wide (reaching tens of km) and deep (sometimes several km) subparallel scarps, ridges, and troughs that extends diagonally across the entire encounter hemisphere, separating the relatively flat plains of Vulcan Planum to the south from the more undulating terrain of Oz Terra in the mid-latitudes. Several large craters superposed on the chasmata indicate that this extension is geologically old. Several areas in the observed mid-latitudes are bounded by large continuous scarps, forming intact crustal blocks several hundred kilometers across. These indicate roughly polygonal extension across this terrain, with no preferred direction of extensional stress. Charon’s tectonic features suggest that it experienced a few kilometers of radial expansion (equivalent to a global extensional areal strain of order 1%) early in its history, which is consistent with the presence of an ancient global subsurface ocean that has now frozen.EndFragment.



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