(Georgia Institute of Technology, 2021-08-24)
Dapremont, Angela M.
Mud volcanism, a specific type of subsurface sediment mobilization process known to occur on Earth, has been suggested to explain the formation of morphologically diverse edifices across the surface of Mars. Previous studies have provided valuable knowledge about the morphometry, morphology, and geologic setting of putative Martian mud volcanoes. However, major knowledge gaps pertaining to the compositional characteristics of these features remain. This dissertation primarily focuses on the use of multiple orbital remote sensing datasets to investigate the mineralogical characteristics of putative Martian mud volcanoes. The validity of the mud volcanism hypothesis for pitted cones in a northern hemisphere study region of Mars is assessed, and the mineralogy of postulated Martian mud volcanoes is examined on a global scale through the use of some of the highest resolution orbital datasets currently available to study surface features on Mars. This dissertation also provides supplemental knowledge to these compositional analyses through the incorporation of an expanded morphometric dataset, a spatial analysis methodology, and the first application of an analytical modeling technique to the study of proposed mud volcanoes on Mars. Microbial activity has been documented at both onshore and offshore mud volcanism system sites on Earth. Therefore, the possibility that this geologic process once operated on the surface of Mars is intriguing given the astrobiological potential of the associated locations, as well as the ability to study sediments that would otherwise be inaccessible and possibly represent life in the deep biosphere of a second terrestrial planet in the Solar System. The study of this geologic process on Mars is also worthwhile due to implications for Martian climate, comparative planetology, and future landed mission exploration of the Martian surface.
(Georgia Institute of Technology, 2021-07-27)
Eggers, Gabriel L.
On Earth, evolved felsic crust is commonly associated with plate tectonics, specifically subduction zones, and the role of water in modulating melting conditions and phase equilibria in the mantle and crust. As Mars lacks evidence of both plate tectonics and extensive water, felsic rock is unexpected there. However, new studies via remote sensing and in situ observation indicate a wider range of primary rock compositions on Mars, suggesting an incomplete understanding of how these materials form. Nili Patera, a caldera on the Syrtis Major shield volcano, has been a locus of compositional research on Mars, including the first detection of bedrock spectrally consistent with evolved felsic material. Using visible/near-infrared data from the CRISM instrument aboard the Mars Reconnaissance Orbiter, the extent of this feldspathic terrane in Nili Patera is mapped and its relation to surrounding mafic units is investigated. This provides important controls such as the areal extent (a proxy for volume) and relative age that can be used to constrain its magmatic formation history. A high-silica magma system on Earth, the Laguna del Maule volcanic field in Chile, is also studied. A stochastic magmatic model unifying dynamics and compositional understanding of magma system evolution is used to generate numerous realizations using known Laguna del Maule conditions and exploring a range of unknown magmatic fluxes in the crust. Forward models are developed and used to transform the magmatic model outputs to observable geophysical signals in gravity, magnetotellurics, and seismic velocity, which are evaluated against field measurements to determine a probable history of the Laguna del Maule magmatic system and investigate current arguments about the structure and supports of shallow, silicic systems. Together, these studies elucidate our understanding of how high-silica systems can form and evolve in disparate conditions.