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Much of the geologic activity preserved on Europa’s icy surface has been attributed to tidal deformation, mainly due to Europa’s eccentric orbit. Although the surface is geologically young (30–80Myr), there is little information as to whether tidally-driven surface processes are ongoing. However, a recent detection of water vapor near Europa’s south pole suggests that it may be geologically active...
Pluto and its largest satellite, Charon, currently orbit in a mutually synchronous state; both bodies continuously show the same face to one another. This orbital configuration is a natural end-state for bodies that have undergone tidal dissipation. In order to achieve this state, both bodies would have experienced tidal heating and stress, with the extent of tidal activity controlled by the orbital...
Lineaments are thought to form as tensile cracks due to tidal stress, which is driven mainly by Europa’s eccentric orbit. However, this model would not produce the wide range of lineament azimuths observed on Europa unless the stress in a given region, or the conditions for fault failure, change over time. In this work, we test the ability of two mechanisms that would alter the stress field over time...
We introduce a new mechanical model for producing tidally-driven strike-slip displacement along pre-existing faults on Europa, which we call shell tectonics. This model differs from previous models of strike-slip on icy satellites by incorporating a Coulomb failure criterion, approximating a viscoelastic rheology, determining the slip direction based on the gradient of the tidal shear stress rather...
Variations in diurnal tidal stress due to Europa’s eccentric orbit have been considered as the driver of strike-slip motion along pre-existing faults, but obliquity and physical libration have not been taken into account. The first objective of this work is to examine the effects of obliquity on the predicted global pattern of fault slip directions based on a tidal-tectonic formation model. Our second...
Cycloids, arcuate features observed on Europa’s surface, have been interpreted as tensile cracks that form in response to diurnal tidal stress caused by Europa’s orbital eccentricity. Stress from non-synchronous rotation may also contribute to tidal stress, and its influence on cycloid shapes has been investigated as well. Obliquity, fast precession, and physical libration would contribute to tidal...
The tectonic sequence in the anti-jovian area covered by regional mapping images from Galileo's orbit E15 is determined from a study of cross-cutting relationships among lineament features. The sequence is used to test earlier results from orbit G1, based on lower resolution images, which appeared to display a progressive change in azimuthal orientation over about 90° in a clockwise sense. Such a...
The formation sequence of prominent ridges and other tectonic lineaments on the southern portion of the leading hemisphere of Europa is determined from cross-cutting relationships. These selected features formed fairly recently relative to most of the surface; older lineaments no longer retain clear evidence of cross-cutting. If we assume that this sequence represents the order of formation of cracks...
Two global issues regarding Europa are addressed by a survey of strike-slip faults. First, a common type of terrain that appears to represent convergent sites of surface removal, which may help compensate for substantial widespread dilation along tectonic bands elsewhere, thus helping resolve the problem of conserving global surface area, is identified. Second, evidence for polar wander may provide...
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