reading displacement chapter, in library (not available online). read 18.0-18.4 plus 18.12. concept...
TRANSCRIPT
![Page 1: Reading Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday. Davis and Reynolds “ Structural](https://reader035.vdocuments.mx/reader035/viewer/2022070410/56649ea95503460f94bacbad/html5/thumbnails/1.jpg)
Reading
Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday.
Davis and Reynolds “ Structural Geology of Rocks and Regions” p. 319-370, also on reserve in library
Concept maps not required for D&R chapter
![Page 2: Reading Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday. Davis and Reynolds “ Structural](https://reader035.vdocuments.mx/reader035/viewer/2022070410/56649ea95503460f94bacbad/html5/thumbnails/2.jpg)
Why Study Reverse Faults? Host the largest, and potentially most
destructive earthquakes (subduction zone thrusts). Low dip requires that faults have large surface area in brittle "seismogenic zone" and that this surface area is close to ground surface where we live.
Associated with mountain building and collisional tectonics. Low-angle faults with big displacements have been known since 1800's (Lapworth).
Influence positions of ore deposits (high-angle reverse faults) and hydrocarbons (thrusts).
![Page 3: Reading Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday. Davis and Reynolds “ Structural](https://reader035.vdocuments.mx/reader035/viewer/2022070410/56649ea95503460f94bacbad/html5/thumbnails/3.jpg)
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Shaw and Shearer: Blind thrust fault beneath Los Angeles metropolitan area, interpreted from seismic reflection profiles and precise earthquake locations
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
![Page 4: Reading Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday. Davis and Reynolds “ Structural](https://reader035.vdocuments.mx/reader035/viewer/2022070410/56649ea95503460f94bacbad/html5/thumbnails/4.jpg)
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Pittman and Ryan
![Page 5: Reading Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday. Davis and Reynolds “ Structural](https://reader035.vdocuments.mx/reader035/viewer/2022070410/56649ea95503460f94bacbad/html5/thumbnails/5.jpg)
Initiating subduction Generally will
reactivate pre-existing structures, such as rift-related features preserved on passive margins (producing continental arc) or transform faults in mid-ocean ridges (producing island arc)
![Page 6: Reading Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday. Davis and Reynolds “ Structural](https://reader035.vdocuments.mx/reader035/viewer/2022070410/56649ea95503460f94bacbad/html5/thumbnails/6.jpg)
Structural components of convergent margins
![Page 7: Reading Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday. Davis and Reynolds “ Structural](https://reader035.vdocuments.mx/reader035/viewer/2022070410/56649ea95503460f94bacbad/html5/thumbnails/7.jpg)
Other elements of thrust belts Thrusting may be
thin-skinned (involving only sedimentary cover) or thick-skinned (involving basement)
Large overturned folds, or nappes (French word for napkin) may form
![Page 8: Reading Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday. Davis and Reynolds “ Structural](https://reader035.vdocuments.mx/reader035/viewer/2022070410/56649ea95503460f94bacbad/html5/thumbnails/8.jpg)
Accretionary tectonics First recognized in
North American Cordillera
Far-traveled terranes may have docked to continent along either reverse or strike-slip faults
![Page 9: Reading Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday. Davis and Reynolds “ Structural](https://reader035.vdocuments.mx/reader035/viewer/2022070410/56649ea95503460f94bacbad/html5/thumbnails/9.jpg)
X-section through Cordilleran Terranes
Sutures bound accreted terranes Exotic terranes include arcs,
microcontinents, and slivers of colliding continental material
![Page 10: Reading Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday. Davis and Reynolds “ Structural](https://reader035.vdocuments.mx/reader035/viewer/2022070410/56649ea95503460f94bacbad/html5/thumbnails/10.jpg)
Much of what we know about thrust terranes is a gift of erosion
Klippe (pl. klippen), from German word meaning ‘slice’, is the erosional remnant of a hanging wall
Window is an erosional hole through hanging wall, allowing footwall to be viewed
Autochthonous material is in place
Allocthonous material has been transported along faults from location of origin
![Page 11: Reading Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday. Davis and Reynolds “ Structural](https://reader035.vdocuments.mx/reader035/viewer/2022070410/56649ea95503460f94bacbad/html5/thumbnails/11.jpg)
Elements of a fold and thrust belt. Note the asymmetry of both horse geometry and folds that records transport direction (also known as vergence)
![Page 12: Reading Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday. Davis and Reynolds “ Structural](https://reader035.vdocuments.mx/reader035/viewer/2022070410/56649ea95503460f94bacbad/html5/thumbnails/12.jpg)
Break-thrust fold
![Page 13: Reading Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday. Davis and Reynolds “ Structural](https://reader035.vdocuments.mx/reader035/viewer/2022070410/56649ea95503460f94bacbad/html5/thumbnails/13.jpg)
Development and 3D form of a fault-bend fold
![Page 14: Reading Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday. Davis and Reynolds “ Structural](https://reader035.vdocuments.mx/reader035/viewer/2022070410/56649ea95503460f94bacbad/html5/thumbnails/14.jpg)
Fault propagation fold
![Page 15: Reading Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday. Davis and Reynolds “ Structural](https://reader035.vdocuments.mx/reader035/viewer/2022070410/56649ea95503460f94bacbad/html5/thumbnails/15.jpg)
Trishear zones exhibit tighter folds with increased proximity to fault tip (blind thrust)
![Page 16: Reading Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday. Davis and Reynolds “ Structural](https://reader035.vdocuments.mx/reader035/viewer/2022070410/56649ea95503460f94bacbad/html5/thumbnails/16.jpg)
Patterns of detachment folds are less regular than other fault-related folds
![Page 17: Reading Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday. Davis and Reynolds “ Structural](https://reader035.vdocuments.mx/reader035/viewer/2022070410/56649ea95503460f94bacbad/html5/thumbnails/17.jpg)
Extension may also occur locally in association with subduction zones
![Page 18: Reading Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday. Davis and Reynolds “ Structural](https://reader035.vdocuments.mx/reader035/viewer/2022070410/56649ea95503460f94bacbad/html5/thumbnails/18.jpg)
…Or in association with continent-continent collisions, where ‘orogenic collapse’ is one way that mountain systems achieve isostatic equilibrium
![Page 19: Reading Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday. Davis and Reynolds “ Structural](https://reader035.vdocuments.mx/reader035/viewer/2022070410/56649ea95503460f94bacbad/html5/thumbnails/19.jpg)
Mechanical paradox Thrust movement on low-
angle surface with ‘typical’ coefficient of friction of rock requires stresses high enough to break the rock
To understand how this motion takes place, we need to think about concepts of displacement, stress, and fault mechanics
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
![Page 20: Reading Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday. Davis and Reynolds “ Structural](https://reader035.vdocuments.mx/reader035/viewer/2022070410/56649ea95503460f94bacbad/html5/thumbnails/20.jpg)
Three descriptions of mechanical interactions Displacement describes the movement of
particles with respect to an external reference frame
Deformation can be described by a displacement field Translation Rotation Shape change (distortion) = strain
Stress is force per unit area
![Page 21: Reading Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday. Davis and Reynolds “ Structural](https://reader035.vdocuments.mx/reader035/viewer/2022070410/56649ea95503460f94bacbad/html5/thumbnails/21.jpg)
Components of Deformation
![Page 22: Reading Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday. Davis and Reynolds “ Structural](https://reader035.vdocuments.mx/reader035/viewer/2022070410/56649ea95503460f94bacbad/html5/thumbnails/22.jpg)
Deformation
![Page 23: Reading Displacement chapter, in library (not available online). Read 18.0-18.4 plus 18.12. Concept map due Wednesday. Davis and Reynolds “ Structural](https://reader035.vdocuments.mx/reader035/viewer/2022070410/56649ea95503460f94bacbad/html5/thumbnails/23.jpg)
Three categories of displacement
Relative particle motion can be described even if part of the system is fixed in space