slide1
Download
Skip this Video
Download Presentation
structural geology & mountain building

Loading in 2 Seconds...

play fullscreen
1 / 22

structural geology & mountain building - PowerPoint PPT Presentation


  • 166 Views
  • Uploaded on

structural geology & mountain building. key terms. Deformation – change in the original form, size or shape of a rock unit Stress – amount of force applied to a given area Differential stress – stress applied unequally in different directions

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' structural geology & mountain building' - anila


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
key terms
key terms
  • Deformation – change in the original form, size or shape of a rock unit
  • Stress – amount of force applied to a given area
  • Differential stress – stress applied unequally in different directions
  • Strain – causes irreversible changes in the shape, size or orientation of a rock unit
  • Elastic deformation – recoverable stress, when stress is removed rock returns to its original shape & size
  • Ductile deformation – elastic limit of rock is exceeded, the rock flows into a new shape, size or orientation
  • Brittle deformation – elastic limit and ductile limit of rock is surpassed, failure occurs, the rock breaks
  • Joint – a crack along which there is no motion
stress strain deformation
Stress,strain &deformation
  • When does failure occur?
  • How is deformation in a stick like deformation of a rock unit?
effects of directional stress
effects of directional stress
  • Compress ional stress – causes rock units to shorten horizontally & thicken vertically
  • Tensional stress – causes rock units to lengthen horizontally & thin vertically
  • Shear stress – causes horizontal displacement along fault zones
strike dip
strike & dip
  • Strike – compass direction of a line where a rock layer intersects the horizontal
  • Dip – angle of inclination or tilt of a rock layer from the horizontal
terminology of folds
Terminologyof folds
  • Limb – sides of a fold
  • Axial plane – imaginary plane that divides a fold as symmetrically as possible
  • Axis – intersection of axial plane with the surface
  • Symmetrical – limbs are mirror images of each other
  • Asymmetrical – limbs are not mirror images of each other
  • Overturned – a fold in which one limb is tilted beyond the vertical
  • Recumbent – a fold folded over on itself
  • Plunge – a fold in which the axis is tilted from the horizontal
types of folds
types of folds
  • Syncline – downwarping of strata, older strata are found on limbs, younger strata in the axial region
types of folds1
types of folds
  • Anticline – upwarping of strata, older strata are found in axial region, younger strata on the limbs
types of folds2
types of folds
  • Asymmetrical – either an anticline or syncline in which one limb is tilted at a different angle than the other
types of folds3
types of folds
  • Recumbent – a fold which is folded over on itself
fault terminology
fault terminology
  • Fault – fracture in rock along which there has been displacement
  • Hanging wall – rock surface above the fault
  • Footwall – rock surface below the fault
  • Fault scarp – exposed fault surface
types of faults
types of faults
  • Normal fault – a fault in which the hanging wall moves down relative to the footwall
types of faults1
types of faults
  • Reverse fault – a fault in which the hanging wall moves up relative to the footwall
types of faults2
types of faults
  • Strike-slip fault – a fault in which the motion is in the horizontal plane, also a transform fault
types of faults3
types of faults
  • Thrust fault – hanging wall moves up and thrusts over the footwall, the dip is less than 45 degrees, low angle fault
domes basins
domes & basins
  • Basin – circular or elongated structure caused by downwarping of sedimentary rock
  • Youngest rock found in the center of the basin, older on the flanks
  • Dome – circular or elongated structure caused by upwarping of sedimentary rock, usually overlying igneous or metamorphic rock
  • Youngest rock found on the flanks of the dome, oldest in the center
hogbacks
Hogbacks
  • Ridges of steeply dipping strata
  • Highly resistant sedimentary layers remain exposed along the edge of an uplifted block
orogenesis
orogenesis
  • Orogenesis – processes by which mountain belts are created
  • Oros – mountain, genesis – to come into being
types of mountains
Types of mountains
  • Fault block mountains – mountain belts formed by extensional forces
  • Mountains are associated with high angle normal faulting
  • Examples include: Sierra Nevada, Grand Tetons, “Basin & Range province
types of mountains1
Types of mountains
  • Folded mountains – result from large scale compressional forces
  • Rock units are shortened and thickened as a series of synclines and anticlines forms a mountain belt
  • Examples include: the Appalachians Valley and Ridge Province
terrane accretion
Terrane accretion
  • Small crustal fragments collide and merge with larger continental masses
  • Accreted crustal blocks are called terranes
  • Accretion of larger fragments may result in formation of a mountain range
  • Examples include: the western coast of North America
ad