Dextral: Difference between revisions
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#REDIRECT[[Sinistral and dextral]] |
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{{Merge|sinistral|Talk:Sinistral|date=August 2007}} |
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'''Dextral''' or ''right lateral'' refers to the horizontal movement of blocks on either side of a [[Fault (geology)|fault]] or the sense of movement within a [[Shear (geology)|shear]]. |
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Movement is dextral (right handed) if the block on the other side of the fault moves to the right, or if straddling the fault the right side moves toward the observer. |
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Dextral gains its origins from the Latin "dexter" for right-handed. The opposite sense of movement [[sinistral]] gains its name from the Latin "sinister" for left-handed. |
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[[image:strike_slip_fault.png|frame|none|''Schematic illustration of the two strike-slip fault types. The view is of the Earth's surface as from space.'']] |
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===Identifying sense of throw=== |
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Identifying the sense of throw of a fault or the sense of [[Shear (geology)|shear]] can be achieved via several methods: |
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* Mappable offset of rock units |
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* Offset of visible bedding, cross cutting dykes |
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* Folding of [[stratum|strata]] proximal to a fault caused by ''frictional drag'' |
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* [[rock microstructure|Shear sense indicators]] in sheared rocks such as |
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** [[Mica fish]] |
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** [[Vein (geology)|Extensional veins]] |
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** Shear deflections and stair-stepping of shear [[Foliation (geology)|folia]] (figure 1, figure 2). |
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[[Image:boudinage.jpg|thumb|left|Figure 1.<br> [[Boudinage]]d [[jasperoid]] in sheared basalt, Fortnum Gold Mine, Australia. Example of dextral shear.]][[image:boudin_vein.jpg|thumb|right|Figure 2. <br>Boudinaged quartz vein in dextral shear foliation, Starlight Pit, Fortnum Gold Mine, Western Australia.]] |
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{{-}} |
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==See also== |
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*[[Fault (geology)]] |
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**[[Thrust fault]] |
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*[[Sinistral]] |
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*[[Transform boundary]] |
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*[[Shear (geology)]] |
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==References== |
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*[http://www.glossary.oilfield.slb.com/DisplayImage.cfm?ID=142 Schlumberger Oilfield Glossary] |
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[[Category:Structural geology]] |
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Revision as of 04:40, 25 August 2007
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