Polygonal deformation bands

• DOI: 10.1016/j.jsg.2015.10.003
• Publication Date: 2015-10-25T12:02:16Z
• Authors: Marco Antonellini; Pauline Nella Mol...
• Keywords: Arches National Park (Utah, USA); Deformation bands; Fault propagation and interaction; Homogeneous strain; Polygonal faults; Porous sandstone; Strain hardening; Geology; 01 natural sciences; 0105 earth and related environmental sciences

Abstract We report for the first time the occurrence of polygonal faults in sandstone, which is compelling given that layer-bound polygonal fault systems have been observed so far only in fine-grained sediments such as clay and chalk. The polygonal faults are shear deformation bands that developed under shallow burial conditions via strain hardening in dm-wide zones. The edges of the polygons are 1–5 m long. The shear deformation bands are organized as conjugate faults along each edge of the polygon and form characteristic horst-like structures. The individual deformation bands have slip magnitudes ranging from a few mm to 1.5 cm; the cumulative average slip magnitude in a zone is up to 10 cm. The deformation bands heaves, in aggregate form, accommodate a small isotropic horizontal extension (strain