Brittle deformation and slope failure at the North Menan Butte tuff cone, Eastern Snake River Plain, Idaho

Journal of Volcanology and Geothermal Research
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Abstract

The manifestation of brittle deformation within inactive slumps along the North Menan Butte, a basaltic tuff cone in the Eastern Snake River Plain, is investigated through field and laboratory studies. Microstructural observations indicate that brittle strain is localized along deformation bands, a class of structural discontinuity that is predominant within moderate to high-porosity, clastic sedimentary rocks. Various subtypes of deformation bands are recognized in the study area based on the sense of strain they accommodate. These include dilation bands (no shear displacement), dilational shear bands, compactional shear bands and simple shear bands (no volume change). Measurements of the host rock permeability between the deformation bands indicate that the amount of brittle strain distributed throughout this part of the rock is negligible, and thus deformation bands are the primary means by which brittle strain is manifest within this tuff. Structural discontinuities that are similar in appearance to deformation bands are observed in other basaltic tuffs. Therefore deformation bands may represent a common structural feature of basaltic tuffs that have been widely misclassified as fractures. Slumping and collapse along the flanks of active volcanoes strongly influence their eruptive behavior and structural evolution. Therefore characterizing the process of deformation band and fault growth within basaltic tuff is key to achieving a more complete understanding of the evolution of basaltic volcanoes and their associated hazards.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Brittle deformation and slope failure at the North Menan Butte tuff cone, Eastern Snake River Plain, Idaho
Series title Journal of Volcanology and Geothermal Research
DOI 10.1016/j.jvolgeores.2014.04.013
Volume 278–279
Year Published 2014
Language English
Publisher Elsevier
Contributing office(s) Astrogeology Science Center
Description 10 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Journal of Volcanology and Geothermal Research
First page 86
Last page 95
Country United States
State Idaho
Other Geospatial Snake River