Propagation energies inferred from deformation bands in sandstone

摘要

Propagation energies for five examples of deformation bands in porous sandstones from four field sites in Nevada, Utah, and France were calculated by using the /-integral approach. Pure compaction bands that accommodate primarily closing displacements from the Valley of Fire (Nevada) site have a closing-mode band propagation energy of J_I = 5.5 ± 1.6 kJ/m~2. Shear-enhanced compaction bands having subequal amounts of normal (closing) and shear strains across them from the same site have propagation energies of J_I = 6.11 ± 1.8 kJ/m~2 and J_(II) = 1.52 ± 0.5 kJ/m~2 for closing and shearing modes respectively. Closing- and shearing-mode band propagation energies for shear-enhanced compaction bands from the Buckskin Gulch (Utah) site, 5.63 ±1.7 and 1.91 ± 0.57 kJ/m~2 and the Uchaux (France) site, 11.0 ± 3.3 and 2.35 ± 0.7 kJ/m~2 respectively are comparable to the values for similar structures from the Valley of Fire site.