Diffuse flux and carbon isotope composition of carbon dioxide emitted from Valles caldera, Yellowstone caldera, and southwestern Utah geothermal sites

Author

Kristen Rahilly, Doctoral Student, Earth and Planetary SciencesFollow

Publication Date

Spring 5-14-2020

Abstract

Carbon dioxide (CO₂) has the lowest solubility in silicate melt and is one of the most abundant and earliest degassed species present in volcanic and geothermal systems. A significant quantity of CO₂ is passively degassed through soils in volcanic and geothermal systems, called diffuse degassing. In Chapter 1, I measure the diffuse CO₂ flux over the site of a prospective enhanced geothermal system in southwestern Utah. I conclude that the CO₂ emitted from soils in the enhanced geothermal site is biogenically-sourced. In Chapter 3, I examine the diffuse CO₂ flux from Roosevelt Hot Springs and two cold gas seeps north of the Cove Fort geothermal area in southwestern Utah. I conclude that diffuse CO₂ emissions from the cold gas seep sites can be higher than the emissions from the high temperature steaming ground at Roosevelt Hot Springs. Chapters 2 and 3 examine diffuse CO₂ flux emissions from caldera-hosted hydrothermal systems. I use diffuse CO₂ flux measurements to calculate the total diffuse CO₂ flux from Yellowstone caldera in northwestern Wyoming and Valles caldera in north-central New Mexico. I show that cold degassing soils emit just as much or more diffuse CO₂ than thermally elevated soils. This has significant implications for how deeply sourced CO₂ eventually reaches the surface. I take the total diffuse CO₂ flux calculated for individual sites and extrapolate that total to the entirety of Yellowstone and Valles calderas, concluding that diffuse CO₂ emissions from caldera-hosted hydrothermal systems are significant contributors to the total CO₂ emitted from volcanoes globally.

Degree Name

Earth and Planetary Sciences

Level of Degree

Doctoral

Department Name

Department of Earth and Planetary Sciences

First Committee Member (Chair)

Tobias Fischer

Second Committee Member

Louis Scuderi

Third Committee Member

Laura Crossey

Fourth Committee Member

Peter Fawcett

Fifth Committee Member

Cristina Takacs-Vesbach

Language

English

Keywords

carbon dioxide, Yellowstone, Valles, caldera, geothermal, hydrothermal

Document Type

Dissertation

Recommended Citation

Rahilly, Kristen. "Diffuse flux and carbon isotope composition of carbon dioxide emitted from Valles caldera, Yellowstone caldera, and southwestern Utah geothermal sites." (2020). https://digitalrepository.unm.edu/eps_etds/440