Mantle 3He and CO2 degassing in carbonic and geothermal springs of Colorado and implications for neotectonics of the Rocky Mountains

TitleMantle 3He and CO2 degassing in carbonic and geothermal springs of Colorado and implications for neotectonics of the Rocky Mountains
Publication TypeJournal Article
Year of Publication2013
AuthorsKarlstrom KE, Crossey LJ, Hilton DR, Barry PH
JournalGeology
Volume41
Pagination495-498
Date Published2013/04
Abstract

Helium isotope (3He/4He) data from geothermal springs in the Colorado Rocky Mountains (western United States) provide unequivocal evidence for a remarkable mantle-to-groundwater connection, with contributions of up to 27% mantle-derived helium. Hydrochemical modeling of springs shows the mantle helium is associated with high pCO2 with 76 ± 20% of the CO2 also derived from endogenic (deep geologic) sources. These springs occur preferentially along faults, have highest 3He/4He values above domains of low mantle velocity, and demonstrate unexpectedly widespread neotectonic mantle degassing. Total CO2 flux through these springs is 3 × 108 mol/yr, a small but persistent contribution to the CO2 budget and an important baseline for carbon sequestration/leakage studies.

DOI10.1130/g34007.1
Short TitleGeology
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