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Title: Dual stable isotopes of CH 4 from Yellowstone hot-springs suggest hydrothermal processes involving magmatic CO 2

Abstract

Volcanism and post-magmatism contribute both significant annual CH 4 fluxes to the atmosphere (on par with other natural sources such as forest fire and wild animal emissions) and have been implicated in past climate-change events. The Yellowstone hot spot is one of the largest volcanic systems on Earth and is known to emit methane in addition to other greenhouse gases (e.g. carbon dioxide) but the ultimate source of this methane flux has not been elucidated. Here we use dual stable isotope analysis (δ 2H and δ 13C) of CH 4(g) sampled from ten high-temperature geothermal pools in Yellowstone National Park to show that the predominant flux of CH4(g) is abiotic. The average δ 13C and δ 2H values of CH 4(g) emitted from hot springs (-26.7 (±2.4) and -236.9 (±12.0) ‰, respectively) are not consistent with biotic (microbial or thermogenic) methane sources, but are within previously reported ranges for abiotic methane production. Correlation between δ 13C CH4 and δ 13C-dissolved inorganic C (DIC) also suggests that CO 2 is a parent C source for the observed CH 4(g). Moreover, CH 4-CO 2 isotopic geothermometry was used to estimate CH 4(g) formation temperatures ranging from ~ 250 - 350°C, which ismore » just below the temperature estimated for the hydrothermal reservoir and consistent with the hypothesis that subsurface, rock-water interactions are responsible for large methane fluxes from this volcanic system. An understanding of conditions leading to the abiotic production of methane and associated isotopic signatures are central to understanding the evolutionary history of deep carbon sources on Earth.« less

Authors:
ORCiD logo; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1378022
Report Number(s):
PNNL-SA-121866
Journal ID: ISSN 0377-0273; KP1601010
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Volcanology and Geothermal Research; Journal Volume: 341; Journal Issue: C
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; stable isotopes; hydrothermal; Yellowstone National Park; deep carbon; me; greenhouse gas

Citation Formats

Moran, James J., Whitmore, Laura M., Jay, Zackary J., Jennings, Ryan deM., Beam, Jacob P., Kreuzer, Helen W., and Inskeep, William P. Dual stable isotopes of CH 4 from Yellowstone hot-springs suggest hydrothermal processes involving magmatic CO 2. United States: N. p., 2017. Web. doi:10.1016/j.jvolgeores.2017.05.011.
Moran, James J., Whitmore, Laura M., Jay, Zackary J., Jennings, Ryan deM., Beam, Jacob P., Kreuzer, Helen W., & Inskeep, William P. Dual stable isotopes of CH 4 from Yellowstone hot-springs suggest hydrothermal processes involving magmatic CO 2. United States. doi:10.1016/j.jvolgeores.2017.05.011.
Moran, James J., Whitmore, Laura M., Jay, Zackary J., Jennings, Ryan deM., Beam, Jacob P., Kreuzer, Helen W., and Inskeep, William P. Sat . "Dual stable isotopes of CH 4 from Yellowstone hot-springs suggest hydrothermal processes involving magmatic CO 2". United States. doi:10.1016/j.jvolgeores.2017.05.011.
@article{osti_1378022,
title = {Dual stable isotopes of CH 4 from Yellowstone hot-springs suggest hydrothermal processes involving magmatic CO 2},
author = {Moran, James J. and Whitmore, Laura M. and Jay, Zackary J. and Jennings, Ryan deM. and Beam, Jacob P. and Kreuzer, Helen W. and Inskeep, William P.},
abstractNote = {Volcanism and post-magmatism contribute both significant annual CH4 fluxes to the atmosphere (on par with other natural sources such as forest fire and wild animal emissions) and have been implicated in past climate-change events. The Yellowstone hot spot is one of the largest volcanic systems on Earth and is known to emit methane in addition to other greenhouse gases (e.g. carbon dioxide) but the ultimate source of this methane flux has not been elucidated. Here we use dual stable isotope analysis (δ2H and δ13C) of CH4(g) sampled from ten high-temperature geothermal pools in Yellowstone National Park to show that the predominant flux of CH4(g) is abiotic. The average δ13C and δ2H values of CH4(g) emitted from hot springs (-26.7 (±2.4) and -236.9 (±12.0) ‰, respectively) are not consistent with biotic (microbial or thermogenic) methane sources, but are within previously reported ranges for abiotic methane production. Correlation between δ13CCH4 and δ13C-dissolved inorganic C (DIC) also suggests that CO2 is a parent C source for the observed CH4(g). Moreover, CH4-CO2 isotopic geothermometry was used to estimate CH4(g) formation temperatures ranging from ~ 250 - 350°C, which is just below the temperature estimated for the hydrothermal reservoir and consistent with the hypothesis that subsurface, rock-water interactions are responsible for large methane fluxes from this volcanic system. An understanding of conditions leading to the abiotic production of methane and associated isotopic signatures are central to understanding the evolutionary history of deep carbon sources on Earth.},
doi = {10.1016/j.jvolgeores.2017.05.011},
journal = {Journal of Volcanology and Geothermal Research},
number = C,
volume = 341,
place = {United States},
year = {Sat Jul 01 00:00:00 EDT 2017},
month = {Sat Jul 01 00:00:00 EDT 2017}
}