Date of Award
Fall 2023
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Geology and Geophysics
First Advisor
Korenaga, Jun
Abstract
Life on Earth traces back to the planet's early geological eons, namely the late Hadean and early Archean. However, direct geological evidence from this period is scarce, necessitating reliance on understanding crust-mantle differentiation and the evolution of atmosphere and oceans to study early Earth habitability. Despite its importance, significant debate surrounds the specific characteristics of Earth's early environment. In this dissertation, we focus on deciphering the chemical and physical evolution of the coupled crust-mantle-atmosphere-ocean system throughout Earth's history, providing insights into continental formation, atmospheric carbon dioxide levels, and ocean pH—essential factors influencing the emergence and development of life on Earth. To achieve this, we first constrain the history of continental formation using observations of atmospheric argon ratios, seawater oxygen isotopic signatures, and mantle hafnium and neodymium isotopic signatures. Next, we develop a new statistical model of the halogen budget within the solid Earth, inferring the evolution of the deep halogen cycle. Lastly, we integrate the results from the previous two steps to constrain the evolution of seawater pH.By combining geophysics, geochemistry, and solid Earth evolution, we present a dynamic view of Earth's system evolution and habitability. Although interpreting ancient geological and geochemical records poses challenges due to non-uniqueness, the theoretical framework developed in this dissertation seamlessly incorporates robust observations and holds potential for assimilating future data. In summary, this dissertation sheds light on Earth's early habitability, unveiling the physical mechanisms that led to a favorable surface condition for life's development. Utilizing a multifaceted approach encompassing geophysics, geochemistry, and solid Earth evolution, we aim to present a dynamic view of Earth's system evolution and habitability. While interpreting geological and geochemical records stored in ancient rocks remains challenging, the theoretical framework developed in this dissertation can integrate robust observations cohesively and accommodate future data.
Recommended Citation
Guo, Meng, "Deciphering the Habitability of the Early Earth: Insights from the Coupled Evolution of the Crust-Mantle-Atmosphere-Ocean System" (2023). Yale Graduate School of Arts and Sciences Dissertations. 1134.
https://elischolar.library.yale.edu/gsas_dissertations/1134
