Author : James J. Moran
Publisher :
ISBN 13 :
Total Pages : 6 pages
Book Rating : 4.:/5 (13 download)
Book Synopsis Dual Stable Isotopes of CH 4 from Yellowstone Hot-springs Suggest Hydrothermal Processes Involving Magmatic CO 2 by : James J. Moran
Download or read book Dual Stable Isotopes of CH 4 from Yellowstone Hot-springs Suggest Hydrothermal Processes Involving Magmatic CO 2 written by James J. Moran and published by . This book was released on 2017 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volcanism and post-magmatism contribute significant annual methane (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 CH4 (as well as carbon dioxide (CO2) and other gases), but the ultimate sources of this CH4 flux have not been elucidated. Here we use dual stable isotope analysis (?2 H and ?13C) of CH4 sampled from ten high-temperature geothermal pools in Yellowstone National Park along with other isotopic and gas analyses to evaluate potential sources of methane. The average ?13C and ?2 H values of CH4 emitted from hot springs (26.7 (±2.4) and ?236.9 (±12.0) ?, respectively) are inconsistent with microbial methanogenesis but do not allow distinction between thermogenic and abiotic sources. Correlation between ?13CCH4 and ?13C of dissolved inorganic C (DIC) is consistent with DIC as the parent C source for the observed CH4, or with equilibration of CH4 and DIC. Methane formation temperatures estimated by isotopic geothermometry based on ?13CCH4 and ?13CCO2 ranged from ~250? 350 °C, which is just below previous temperature estimates for the hydrothermal reservoir. Further, the ?2 HH2O of the thermal springs and the measured ?2 HCH4 values are consistent with equilibration between the source water and the CH4 at the formation temperatures. Though the ultimate origin of the CH4 could be attributed to either abiotic of themorgenic processes with subsequent isotopic equilibration, the C1/C2+ composition of the gases is more consistent with abiotic origins for most of the samples. Thus, our data support the hypothesis that subsurface rock-water interactions are responsible for at least a significant fraction of the CH4 flux from the Yellowstone National Park volcanic system.