Fracture of Antarctic Ice Shelves and Implications for the Icy Satellites of the Outer Solar System.

Planetary Science;Glaciology;Tectonics;Icy Satellites;Antarctic Ice Shelves;Atmospheric;Oceanic and Space Sciences;Geology and Earth Sciences;Science;Atmos, Oceanic & Space Sciences

Walker, Catherine ColelloNagy, Andrew F. ;

University of Michigan

关键词: Planetary Science;    Glaciology;    Tectonics;    Icy Satellites;    Antarctic Ice Shelves;    Atmospheric;    Oceanic and Space Sciences;    Geology and Earth Sciences;    Science;    Atmos, Oceanic & Space Sciences;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/99854/catcolwa_2.pdf?sequence=2&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Recent observations have revealed that many icy satellites of the outer solar system either are--or were geologically recently--active, evidenced by highly-fractured surfaces and eruption-modified landscapes. It is likely that this activity results from tidal and tectonic stresses throughout their evolution. While it is not feasible at current to study these satellites through fieldwork or even extended remote sensing campaigns, it is possible to study possibly analogous features on Earth to constrain models and improve understanding of fracturing processes that may have occurred there. Morphologically similar to fracture systems observed in the icy moons, large rift systems propagate in terrestrial ice shelves, floating extensions of ice sheets over water. This dissertation presents results from observations of ice shelf rift propagation, and the use of these results in a comparative study of deformation and fracturing in the icy moons. In observing 78 ice shelf rifts around the Antarctic Ice Sheet, we found that variability in rift behavior could not be explained by changing environmental conditions that had previously been suggested to modulate rift propagation, like atmospheric temperature and ocean swell. Instead, we found variability can likely be attributed to structural heterogeneity within the ice and rift location and geometry, in that we found that open-ended rifts adjacent to the ocean at ice shelf fronts were susceptible to tsunamis. We also found that closely-spaced rifts;; behavior was affected by interaction. Motivated by this observation, we showed that closely-spaced surface fractures in the icy moons cannot fully penetrate the shell thicknesses previously predicted. Instead, we argue that a combination of surface and bottom cracks and shear failure must exist for a fracture to reach a subsurface reservoir. We also argue that the bizarre set of features at Enceladus;; south pole may be the result of localized thinning, which caused extensional and compressional fracture formation at that location, a phenomenon also seen on Earth. The work presented demonstrates the advantages of comparative study, as we develop an improved set of observations for Antarctic ice shelf rift propagation and use those results to advance the current state of knowledge of planetary properties and processes.