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Dissertation
Modeling the Dynamics of Icy and Rocky Planetary Shells
Washington State University
Doctor of Philosophy (PhD), Washington State University
01/2022
DOI:
https://doi.org/10.7273/000004419
Handle:
https://hdl.handle.net/2376/125094
Abstract
I undertake an examination of the diversity of surface geology and expression in our solar system through three separate studies of various icy and rocky planetary shells. First, I model the formation via crystallization of icy planetary shells, applying the results specifically to the Jovian Satellite Europa. Using a one-dimensional thermodynamic crystallization model, I estimate the thermal equilibrium thickness of a fully crystallized ice shell as well as its formation time, and study how these results may change in various states of tidal heat generation. I find that icy shells may form faster than previously thought, in 2 million years or less, reaching thicknesses of up to 30 km with icy lithospheres less than 8 km thick. Next, I examine a novel formational interpretation of recently described “subsumption zones” on the Europa’s icy surface. I propose that these features, interpreted as direct analogues to Earth’s subduction zones, may have formed in part by the viscous collapse of the shell’s lithosphere. I model this viscous lithospheric collapse to evaluate whether surface ice is capable of participating in this delamination process, and how the properties of the delaminating lithosphere may affect surface movement and sinking. I discover that this delamination process may involve both convergent and extensional ice behavior. The icy extension may explain cryovolcanic deposits observed on the surface of these subsumption zones. Icy convergence may facilitate the initiation of ice subduction processes through the weakening and movement of the ice. Finally, I examine the history and formation of ancient Venusian mountain belts termed the tesserae. I analogize these Tesserae to ancient Earth lithospheric blocks termed Cratons, considered to be among the oldest and strongest units of continental material found on Earth. I apply a recent model of craton formation, in which they form during a transition from an ancient, stagnant lid mode to modern plate tectonics, to ideas of Venusian planetary evolution. I discover that it is feasible for the Tesserae to form during an episode of catastrophic lithospheric breakage, alongside dramatic mantle dehydration and climate change that subsequently prevented the development of an Earth-like plate tectonic regime.
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Details
- Title
- Modeling the Dynamics of Icy and Rocky Planetary Shells
- Creators
- Austin Patrick Green
- Contributors
- Catherine M Cooper (Advisor)Eric Mittelstaedt (Committee Member)Sean P Long (Committee Member)John Wolff (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Environment, School of the (CAHNRS)
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 152
- Identifiers
- OCLC#: 1365390594; 99900883239201842
- Language
- English
- Resource Type
- Dissertation