Exploring the Enstatite Chondrites: Modal Abundances, Metamorphic History, and Volatile Challenges
This thesis investigates the formation conditions, thermal histories, and volatile inventories of enstatite chondrites (ECs). A diverse set of ECs is analyzed to capture the broad variability within this meteorite class. Chapter 1 presents a comparative analysis of mineral abundances using automated point counting, X-ray diffraction analysis, and XMapTools-based phase mapping. The results reveal significant variations in silicate and sulfide abundances across EC groups, challenging the conventional binary classification and suggesting distinct formation conditions. Chapter 2 explores the thermal histories of two highly equilibrated EH chondrites, proposing a novel formation mechanism on the parent asteroid: contact metamorphism driven by an impact melt sheet. Chapter 3 integrates bulk, in situ, and isotopic volatile measurements, demonstrating that most detected hydrogen (H) is terrestrial contamination rather than indigenous. However, modeling the H budget of an EC-like parent body suggests a potential contribution to Earth's water budget. Combined, these findings contribute to a more nuanced understanding of EC classification, thermal evolution, and volatile inventory, and add to the broader discussions on early solar system environments, asteroidal processes, and the delivery of volatiles to terrestrial planets.
The Sun and the Solar System, meteorite, enstatite, chondrite, earth, volatiles, hydrogen
City University of New York - Graduate Center
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