26 october 2004glg310 structural geology. 26 october 2004glg310 structural geology shear zones have...
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![Page 1: 26 October 2004GLG310 Structural Geology. 26 October 2004GLG310 Structural Geology Shear Zones Have a look at Davis and Reynolds, Chapter 9](https://reader035.vdocuments.us/reader035/viewer/2022062221/56649d435503460f94a1fdbc/html5/thumbnails/1.jpg)
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Shear Zones
• Have a look at Davis and Reynolds, Chapter 9
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Shear Zones
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Shear Zones
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Shear zones
• Brittle or ductile– Brittle shear zone = fault zone
• Tabular or sheet like, planar or curviplanar zone composed of rocks that are more highly strained than the rocks adjacent to the fault zone
• Quartz starts to flow rather than fracture at about 300C
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Semi-brittle shear zones
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2004 Parkfield EarthquakeRamón Arrowsmith
& special guest Matt Fouch
Earthquake of the Month: Special Seminar
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Brittle-ductile s.z.
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Sense of shear
S-C fabric: S surface = schistosity, C surface = shear surfaces
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Sense of shear
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Sense of shear: Ductile shear zone
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Pure vs. Simple shear
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Pure vs. Simple shear
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Analysis of shear strain
Continuous or discontinuous strain
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Transpression or Transtension
Can have both pure and simple shear along a shear
zone
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-R+AVelocities relative to stable North America
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