Description
- Abstract:
- Asteroids and their meteoritic counterparts are the most accessible, yet most enigmatic solar system materials available for study. Their chemistry and mineralogy provide clues to the conditions that governed the formation and evolution of the solar system. Visible and infrared (VIR) reflectance spectroscopy is the most powerful technique we have for investigating asteroids and establishing their links to meteorites. Despite recent advances in asteroid and meteorite spectroscopy, important questions remain about how to interpret their reflectance spectra and place them in proper solar system context. This dissertation is composed for four chapters that address outstanding issues in meteoritics and asteroid science with the goal of advancing our ability to accurately characterize these primitive materials and the processes that modified them. Chapter 1 explores the diversity of spectral features across multiple spatial scales of CM2 chondrites with a focus on the shape and position of the 3 µm OH/H2O feature. We found these meteorites to exhibit a diversity of “hydration” features, reflecting compositional and textural complexity that is belied by bulk spectroscopic measurements. In Chapter 2 we investigated the Aguas Zarcas meteorite, a fascinating CM2 polymict breccia. Using infrared reflectance spectroscopy and electron probe micro-analysis we explored the relationship between lithologies, which suggested a complex alteration sequence by multiple episodes of alteration by fluids that were neutral to slightly acidic and ranged from 25–75°C. Chapter 3 focuses on the ‘missing mantle conundrum’, the apparent scarcity of olivine-rich mantle material in both the asteroid and meteorite record. By mixing mantle analogs with chondritic material, we explored the hypothesis that posits this mantle material does exist but is masked by dark chondritic material. We find that upwards of 30–60 wt.% mantle can be effectively masked in VIR spectra. In the final chapter, we use infrared spectroscopy to assess the compositional heterogeneity of samples of asteroid Bennu returned by NASA’s OSIRIS-REx mission. We found evidence for (1) extensive modification of the Bennu parent body by fluids that evolved in composition, and (2) that space weathering modified Bennu’s optical surface, causing aromatization and shifts in the position of the 3 µm absorption feature.
- Notes:
- Thesis (Ph. D.)--Brown University, 2024
Citation
Schultz, Cody Davis,
"Infrared Reflectance Spectroscopy of Meteorites, Analogs, and Returned Samples: Advances in Context, Connections, and Characterization"
(2024).
Earth, Environmental and Planetary Sciences Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://repository.library.brown.edu/studio/item/bdr:aj2549vg/
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Earth, Environmental and Planetary Sciences Theses and Dissertations
Theses and Dissertations for the Earth, Environmental and Planetary Sciences department....