Tracing Planetary Scale Volatile Cycling with Inert Gases: A Combined Experimental and Numerical Approach

Krantz, John A.

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Year:: 2019
Contributor:: Krantz, John A (creator); Parman, Stephen (Advisor); Saal, Alberto (Reader); Cooper, Reid (Reader); Huber, Christian (Reader); Barry, Peter (Reader); Brown University. Department of Earth, Environmental, and Planetary Sciences (sponsor)
Genre:: theses
Subject:: Igneous rocks; Gases, Rare; Planets--Geology (Planetary geology); Planets--Atmospheres
Extent:: xii, 177 p.

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Abstract:: Abstract of Tracing Planetary Scale Volatile Cycling with Inert Gases: A Combined Experimental and Numerical Approach, by John A. Krantz, Ph.D., Brown University, May 2020. To better understand the origin of Earth’s volatiles, this thesis represents the results of experiments and numerical models. Despite being physically and biologically important, volatiles like water and carbon dioxide are challenging subjects for analytical investigation. They readily react with any number of other materials and have limited potential for isotopic analysis. There are, however, other volatiles which are less reactive and have a greater variety of isotopic information available. At the extreme opposite end of reactivity are the nominally inert noble gases. The noble gases experience the same physical processes which the major, life-essential volatiles experience without the complexity of chemical interactions. As such, this thesis focuses on improving our understanding of how the noble gases interact with geological materials—particularly during subduction—and the implications thereof. Experimentally-measured solubilities for the full suite of noble gases in natural serpentinite are presented. Serpentinite fractionates the heavy noble gases, with solubilities increasing from Ar to Kr to Xe. Kr/Ar and Xe/Ar ratios in MORB are quite like those predicted for subducted serpentinite, consistent with most heavy noble gases in the MORB-source coming from subducted serpentinite. The results of our model constrain the degree to which the mantle has been processed. The constraints from the coupled N-Xe system are also used to model the evolution of H. These results show that volatile input to the mantle increased during the Archean, consistent with models of the onset of subduction. We also explore the long-term effects of ingassing and outgassing on a planet without subduction. Where the surface of the Earth has been repeatedly processed through mantle melting and subduction, the Martian surface has been, effectively, preserved since its earliest formation. Hydrous minerals, especially clays, produced in the crust in the presence of an early steam atmosphere and hydrosphere could have incorporated and sequestered substantial amounts of Xe. This Xe could be reintroduced to the atmosphere over billion-year timescales, producing the 129Xe anomaly seen today.
Notes:: Thesis (Ph. D.)--Brown University, 2019

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Rights: In Copyright
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Krantz, John A., "Tracing Planetary Scale Volatile Cycling with Inert Gases: A Combined Experimental and Numerical Approach" (2019). Earth, Environmental and Planetary Sciences Theses and Dissertations. Brown Digital Repository. Brown University Library. https://repository.library.brown.edu/studio/item/bdr:1129448/

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Earth, Environmental and Planetary Sciences Theses and Dissertations

Theses and Dissertations for the Earth, Environmental and Planetary Sciences department.
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