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Preservation of an extreme transient geotherm in the Raft River detachment shear zone

R. Gottardi, C. Teyssier, A. Mulch, T. W. Vennemann and M. L. Wells
Preservation of an extreme transient geotherm in the Raft River detachment shear zone
Geology (Boulder) (August 2011) 39 (8): 759-762


Extensional detachment systems separate hot footwalls from cool hanging walls, but the degree to which this thermal gradient is the product of ductile or brittle deformation or a preserved original transient geotherm is unclear. Oxygen isotope thermometry using recrystallized quartz-muscovite pairs indicates a smooth thermal gradient (140 degrees C/100 m) across the gently dipping, quartzite-dominated detachment zone that bounds the Raft River core complex in northwest Utah (United States). Hydrogen isotope values of muscovite (delta D (sub Ms) approximately -100 per mil) and fluid inclusions in quartz (delta D (sub Fluid) approximately -85 per mil) indicate the presence of meteoric fluids during detachment dynamics. Recrystallized grain-shape fabrics and quartz c-axis fabric patterns reveal a large component of coaxial strain (pure shear), consistent with thinning of the detachment section. Therefore, the high thermal gradient preserved in the Raft River detachment reflects the transient geotherm that developed owing to shearing, thinning, and the potentially prominent role of convective flow of surface fluids.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 39
Serial Issue: 8
Title: Preservation of an extreme transient geotherm in the Raft River detachment shear zone
Affiliation: University of Minnesota, Department of Geology and Geophysics, Minneapolis, MN, United States
Pages: 759-762
Published: 201108
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 33
Accession Number: 2011-069069
Categories: Structural geology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2011228
Illustration Description: illus.
N37°00'00" - N42°00'00", W114°04'60" - W109°04'60"
Secondary Affiliation: Universitaet Hannover, DEU, GermanyUniversite de Lausanne, CHE, SwitzerlandUniversity of Nevada Las Vegas, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201138
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