Refining the Formation of Fissures on Europa
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Abstract
Europa is a large moon of Jupiter with an icy crust and a subsurface ocean. Europa orbits close to Jupiter and is tidally locked, so it experiences tidal forces that cause the tectonic, magmatic, and volcanic processes that shape its surface. This relationship has formed two prominent terrain types: ridged plains and chaos terrain. While the ridged plains are dominated by ridges and the chaos by pits and domes, both are home to fractures and gorges (fossae). Studying these landforms could prove useful in deciphering the subsurface's physical, chemical, and mechanical characteristics. Current models of the crust posit a two-layered system with a thinner, brittle outer layer and a thicker, ductile one. However, the exact thickness of these layers and whether this thickness varies over the surface is as controversial as their chemical compositions. Europa's subsurface processes are also debated. The many models of linear landform formation fall into two broad categories: formation via tidal tectonics and formation via indirect tidal forces like tidal heating. The maps and morphological analyses of the landforms in this thesis have contributed to the conversations regarding Europa’s subsurface processes and characteristics. This thesis finds an overabundance of wavy and jagged linea compared to tectonic model predictions. It is, therefore, reasonable to assume that indirect tidal processes such as diapirism are at least partially responsible for these landforms. Bethel (2018) explains that tidal forces will preferentially deform regions of the thinner crust, while on planets with uniform crusts, tidal forces will act more symmetrically. The results of this thesis fit the ladder explanation and thus question the idea of a homogenous Europan crust. The landforms mapped in this thesis could be of speleogenic and geochemical interest. However, the quality and quantity of current Europa data have made this dataset incomplete. Thus, once better data is acquired, this list should be refined and expanded upon before it is used for geochemical or spelogenic research.
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Planetary Geology, Planetary Science, Europa, Geomorphology, Tidal heating