Flow of mantle fluids through the ductile lower crust: Heliumisotope trends

Journal Article · Sun Oct 07 04:00:00 EDT 2007 · Science

DOI:https://doi.org/10.1126/science.1147537· OSTI ID:927196

Kennedy, B Mack; van Soest, Matthijs C

Heat and mass are injected into the shallow crust when mantle fluids are able to flow through the ductile lower crust. Minimum 3He/4He ratios in surface fluids from the northern Basin and Range province, western North America increase systematically from low, crustal values in the east to high, mantle values in the west, a regional trend that correlates with the rates of active crustal deformation. The highest ratios occur where the extension and shear strain rates are greatest. The correspondence of helium isotope ratios and active trans-tensional deformation indicates a deformation enhanced permeability and that mantle fluids can penetrate the ductile lithosphere in regions even where there is no significant magmatism. Superimposed on the regional trend are local, high-{sup 3}He/{sup 4}He anomalies signifying hidden magmatic activity and/or deep fluid production with locally enhanced permeability, identifying zones with high resource potential, particularly for geothermal energy development.

• Research Organization: Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 927196
• Report Number(s): LBNL--63575; BnR: YN0100000
• Journal Information: Science, Journal Name: Science Journal Issue: 5855 Vol. 318; ISSN 0193-4511; ISSN SCEHDK
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
DEFORMATION
GEOTHERMAL ENERGY
HELIUM ISOTOPES
MAGMATISM
PERMEABILITY
PRODUCTION
RESOURCE POTENTIAL
SHEAR
STRAIN RATE