Matching Items (2)
Description
Planetary mineralogy provides important clues about a planet’s geologic history, specifically how the planet first solidified and what geological processes have taken place since. I used spectral and composition data from the Mars Science Laboratory Curiosity rover to study some of the most recent geologic events on Mars. I also used modeled mineralogy of hypothetical exoplanets to understand the initial crystallization of exoplanets. Orbital data of Mt. Sharp, a ~5 km tall mound of sedimentary material, in Gale crater suggests that minerals associated with liquid water are present. These minerals, such as hydrated Mg-sulfates that are left behind as water evaporates, likely represent the beginning of Mars’ transition from a warm wet planet to the cold dry planet it is today.To understand how the mineralogy of Mt. Sharp changed, I used data from the Mastcam instrument on Curiosity to collect visible to near-infrared spectra of rocks from Vera Rubin Ridge and the Carolyn Shoemaker formation. Additionally, I collected laboratory spectra of powered binary mineral mixtures to understand how common minerals such as plagioclase, pyroxene, and hematite might obscure the spectral features of phyllosilicates and Mg-sulfates. Lastly, to better understanding Mars’ mineralogy, I analyzed numerous mixtures with Mg-sulfates in a nitrogen filled glovebox to better represent some of the environmental conditions of present-day Mars.
Minerals such as phyllosilicates and Mg-sulfates, often referred to as secondary minerals, are only found on planets that have experienced alteration since the planet first solidified. The current level of understanding of Martian mineralogy has only been obtained after decades of sending numerous orbital and landed missions with intricate science instruments. But there is not this level of understanding for all planets, and especially not for planets outside of the solar system. Using modeled mineralogy, I deciphered the order in which primary minerals (i.e., olivine, pyroxenes, and plagioclase) could have formed as exoplanets first solidified. Understanding the mineralogy of planetary bodies gives insight into the geologic history of processes that cannot be seen, because they are no longer occurring, or even of planets that are difficult to find.
ContributorsJacob, Samantha Renee (Author) / Bell Iii, James F (Thesis advisor) / Till, Christy B (Committee member) / Desch, Steven J (Committee member) / Robinson, Mark S (Committee member) / Williams, David A (Committee member) / Arizona State University (Publisher)
Created2022
Description
Both volcanic and tectonic landforms are surface expressions of the inner workings of a planet. On Earth, volcanism and crustal deformation are primarily surface expressions of plate tectonics. In contrast, the lunar crust has been deformed by solely endogenic processes following large impact events.The Procellarum KREEP (potassium (K), rare earth elements (REE), and phosphorus (P)) Terrane (PKT) is a thermally and chemically distinct geologic province on the Moon. Despite the wealth of remote sensing data, the origin and evolution of the PKT is poorly understood. This study focuses on floor-fractured craters and silicic magma genesis within the PKT.
First, I present a detailed study of floor-fractured craters, including morphometric measurements using topographic datasets from the Lunar Reconnaissance Orbiter Camera (LROC), variations in temporal heat flow, lithospheric rheology and the locations of floor-fractured craters relative to impact basins. The overarching conclusion is viscous relaxation and magmatic intrusion are not necessarily mutually exclusive, as has been argued in earlier studies. This work also provides new evidence for the existence of the putative Procellarum basin.
Next, with rhyolite-MELTS modeling, I demonstrate that fractional crystallization of KREEP basalt magmas is a plausible mechanism for generating silicic melts. The results suggest that following crystallization, the composition of the remaining ~30 wt.% liquids are consistent with returned lunar silicic fragments.
Finally, using crater counting methods I tested the stratigraphic relationship between the floor-fractured crater, Hansteen, and the silicic volcanic landform, Mons Hansteen. Absolute model ages (AMAs) suggest that the basalts on the floor of Hansteen crater formed contemporaneously with Mons Hansteen, implying that bimodal volcanism might have played a role in silicic magma genesis on the Moon.
ContributorsRavi, Srinidhi (Author) / Robinson, Mark S (Thesis advisor) / Till, Christy B (Committee member) / Watters, Thomas R (Committee member) / Whipple, Kelin X (Committee member) / O'Rourke, Joseph G (Committee member) / Arizona State University (Publisher)
Created2023