Deformation bands

{{Short description|Geological mechanism producing small fault lines}} '''Deformation bands''' are small [[Fault (geology)|faults]] with very small displacements. In the past, these bands have been called Luder's bands or braided shear fractures.<ref name=Schultz>Schultz, R. 2009. Fractures and Deformation Bands in Rock: A Field Guide and Journey into Geologic Fracture Mechanics. Oxford University Press</ref><ref>[http://www.springerlink.com/content/r70236158556gww32/ DOI.org]{{dead link|date=February 2020|bot=medic}}{{cbignore|bot=medic}} </ref> They often precede large faults. They develop in [[Porosity|porous rocks]], such as [[sandstone]]. Material in a deformation band has a much smaller grain size, poorer sorting, and a lower porosity than the original sandstone. They can restrict and/or change the flow of fluids like water and oil. They are common in the [[Colorado Plateau]],<ref>{{Cite web |url=http://folk.uib.no/nglhe/Utah.html |title=Structural geology on the Colorado Plateau |access-date=2009-12-18 |archive-url=https://web.archive.org/web/20110724185916/http://folk.uib.no/nglhe/Utah.html |archive-date=2011-07-24 |url-status=dead }}</ref> where examples occur in the [[Entrada Sandstone]] in the [[San Rafael Swell]] in [[Utah]].<ref name=Schultz />

Deformation bands are present in a variety of porous rock types such as [[sandstone]]s, [[limestone]]s, [[siltstone]]s, poorly welded volcanic [[tuff]]s, and [[breccia]]s. The [[cataclastic]] and compactional bands often form seals and prevent the flow of [[groundwater]] or [[Petroleum|oil]]. In their formation grains shift their packing and are crushed.<ref>Schultz, R. and R. Siddharthan. 2005. A general framework for the occurrence and faulting of deformation bands in porous granular rocks. Tectonophysics: 411. 1-18.</ref>

[[Image:Deformation Bands on Mars.jpg|thumb|The group of lines running up and down in the image are believed to be deformation bands. They can be thought of as small faults.]] The [[Mars Reconnaissance Orbiter]] showed deformation bands in Capen Crater, located in the [[Arabia quadrangle]].<ref>{{Cite web | url=http://mars.jpl.nasa.gov/mro/gallery/press/20080918c.html | title=Mars Reconnaissance Orbiter: Multimedia}}</ref> The bands represent failure by localized frictional sliding.

==References== {{reflist}}

[[Category:Structural geology]]