On Earth, evolved felsic crust is commonly associated with plate tectonics, specifically subduction zones, and preexisting silicic crust. As Mars
lacks both, 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 and its relation to surrounding more 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. An underconstrained magmatic model unifying dynamics and compositional understanding of magma system evolution is used to generate hypothetical histories of the Laguna del Maule system. 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 in general. Together, these studies elucidate our understanding of how high silica systems can form and evolve in disparate conditions.