Fan and Fracture Formation: Morphologic and Sedimentologic Characteristics of Alluvial Fans on Earth and Mars, and Fracture Population Distributions on Europa

Planetary science is inherently limited by the resolution and coverage of the currently available data. What can be observed in person, measured precisely in high-resolution data, or sampled for lab analysis in terrestrial investigations ca only be inferred, modeled, or hypothesized on other planetary bodies. The Earth remains our best tool for understanding the geologic systems of the rest of the Solar System. By applying what is known or can be measured about terrestrial systems, it is possible to determine how large-scale controls and observable features relate to geologic complexity that is beyond the resolution of planetary data. This dissertation presents work in two different geologic regimes – surface sedimentary processes and brittle material structure – and applies contextual relationships developed in terrestrial geologic systems to analogous planetary systems in an effort to gain insight into the smaller-scale complexities that cannot yet be directly measured. Terrestrial sedimentology provides a framework for defining the morphology of depositional features, which is applied to similar features on Mars to differentiate between depositional environments which form during different climatic settings (Chapter 2). Analysis of the primary controls of alluvial fans depositional style in a population of terrestrial fans sourced from basaltic catchments shows a correlation between catchment lithology and sedimentary depositional process that builds the fans (Chapter 1). A more precise understanding of the relationship between depositional environmental controls and the sedimentary characteristics of alluvial fans on Earth provides context for analyzing the sedimentology of alluvial fans on Mars as a potential climatic indicator. Thermal inertia is used as a proxy for analyzing grain size and associated depositional characteristics of alluvial fans on Mars (Chapter 3). In a different geologic system, the size distribution trends observed in fracture populations on Earth are applied to observable fracture populations on Europa to model the abundance of fractures which may be present below the limit of resolution (Chapter 4). By applying terrestrial concepts to remote systems, this dissertation expands our understanding of the complexities of planetary geology on Mars and Europa.