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Morphological Mapping and Tidal Stress Modeling of Strike-Slip Faults on Ganymede.

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Title:Morphological Mapping and Tidal Stress Modeling of Strike-Slip Faults on Ganymede.
Authors:Cameron, Marissa E.
Contributors:Geology & Geophysics (department)
Date Issued:May 2018
Publisher:University of Hawaiʻi at Mānoa
Abstract:Jupiter’s icy moon Ganymede displays a fractured surface with many morphologically
distinct regions of inferred strike-slip faulting that may be important to the structural
development of its surface. Ganymede is dominated by heavily grooved terrain, which is likely
the result of extensive normal faulting, but the role of strike-slip tectonism in shaping the surface
of Ganymede is not well understood. This dissertation addresses strike-slip faulting on
Ganymede in a three-part study. The first part uses detailed maps based on high-resolution
Galileo and Voyager images of nine geologically relevant sites spanning Ganymede’s surface to
document evidence of strike-slip faulting. Abundant evidence of strike-slip faulting exists at each
site, indicating that strike-slip tectonism strongly affects Ganymede’s surface. The second part
combines the detailed mapping results with a numerical tidal stress model (SatStress) that
accounts for Ganymede’s orbital interactions with Jupiter and the other Galilean satellites, as
well as the internal structure of Ganymede. The modeling results suggest, under particular
circumstances, diurnal and secular tidal stresses such as nonsynchronous rotation (NSR) may
have been sufficient to induce Coulomb failure and generate strike-slip faulting. In six of the
nine regions the fault zone’s predicted slip is compatible with the slip deduced from the maps.
The third part focuses on the effects of diurnal tidal stresses alone, and takes into account
Laplace-like resonances among Ganymede, Europa, and Io that may have once led Ganymede to
acquire an eccentricity as high as ~0.07 that may have been stable for 107-109 years. This
previous period of high eccentricity may have allowed diurnal tidal stresses to drive faulting
during a past period of active tectonism. Assuming a conservative eccentricity of 0.05, Coulomb
failure can be achieved without the need to invoke a secular stresses such as NSR, but only for a
past, high eccentricity case and limited depths of less than 250 m. In sum, tidal contributions are
predicted to vary in magnitude over time as the dynamics of the Galilean system evolved, and
can help drive strike-slip faulting. These findings should be of use in future missions to Jupiter
and its Galilean moons.
Description:Ph.D. Thesis. University of Hawaiʻi at Mānoa 2018.
Rights:All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Appears in Collections: Ph.D. - Geology and Geophysics

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