crustal deformation. types of deformation folds faults & joints

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  • Crustal Deformation

  • Crustal DeformationTypes of DeformationFoldsFaults & Joints

  • TermsDip angleAngle of tilt away from horizontal

  • Types of DeformationGEOL131: Crustal Deformation

  • ElasticRock bends but snaps back to original shapeEarthquakes

    Elastic limitCapacity of rock for elastic deformation

    If elastic limit exceeded, deformation is permanent

    GEOL131: Crustal Deformation: Types of Deformation

  • BrittleRock breaks

    Colder, harder, and shallower rock tends to be brittle

    GEOL131: Crustal Deformation: Types of Deformation

  • DuctileRock bends permanently

    Deeper, hotter, weaker rock tends to be ductile

    GEOL131: Crustal Deformation: Types of Deformation

  • FoldsGEOL131: Crustal Deformation

  • Folded RocksProduct of ductile deformation

    Form at deep crustal levelsRock is warmer

    GEOL131: Crustal Deformation

  • Basic Fold AnatomyGEOL131: Crustal Deformation: FoldsAxisLimbLimb

  • Anticlines & SynclinesGEOL131: Crustal Deformation: Folds

  • DomesGEOL131: Crustal Deformation: Folds

  • BasinsGEOL131: Crustal Deformation: Folds

  • MonoclinesGEOL131: Crustal Deformation: Folds

  • Fold OrientationsGEOL131: Crustal Deformation: FoldsSymmetricalBoth limbs have same dip angle

    AsymmetricalLimbs have different dip angles

  • Fold OrientationsGEOL131: Crustal Deformation: FoldsOverturnedOne limb tilted more than 90 degrees

    RecumbentBoth limbs horizontal

  • Fold OrientationsGEOL131: Crustal Deformation: Folds

    UprightFold axis not tilted

    PlungingFold axis is tilted

  • Recognizing folds in map viewGEOL131: Crustal Deformation: Folds

    What patterns do folds make on the Earths surface?

    There is usually no cross-section view available to geologists

  • Recognizing folds in map viewGEOL131: Crustal Deformation: FoldsUpright anticline

    Upright syncline

    Oldest layerYoungest layer

  • Recognizing folds in map viewGEOL131: Crustal Deformation: FoldsUpright anticline

    Upright syncline

    Oldest layer at centerYoungest layer at center

  • Recognizing folds in map viewGEOL131: Crustal Deformation: FoldsArrows show direction of fold axis tiltOldest layer at centerYoungest layer at center

  • Recognizing folds in map viewGEOL131: Crustal Deformation: FoldsDome: oldest layer at centerBasin: youngest layer at center

  • Faults & JointsGEOL131: Crustal Deformation

  • Basic Fault AnatomyGEOL131: Crustal Deformation: Faults & JointsHanging WallFootwall

  • Normal faultsReverse faultsThrust faultsDip-Slip FaultsGEOL131: Crustal Deformation: Faults & Joints

  • Dip-Slip Faults: NormalGEOL131: Crustal Deformation: Faults & Joints

  • Dip-Slip Faults: ReverseGEOL131: Crustal Deformation: Faults & Joints

  • Dip-Slip Faults: ThrustGEOL131: Crustal Deformation: Faults & Joints

  • Normal faultsTensional stressHanging wall moves downReverse faultsCompressional stressHanging wall moves upThrust faultsCompressional stressFootwall moves upLower angle than reverse faultsDip-Slip Faults: SummaryGEOL131: Crustal Deformation: Faults & Joints

  • Left-lateralRight-lateralCaused by shear stressStrike-Slip FaultsGEOL131: Crustal Deformation: Faults & Joints

  • Strike-Slip FaultsGEOL131: Crustal Deformation: Faults & Joints(Right-lateral)

  • JointsFractures with no movement

    Cause accelerated weatheringGEOL131: Crustal Deformation: Faults & JointsWeathered joints in southern Utah

  • Mountain BuildingGEOL131: Crustal Deformation

  • Types of Tectonic Mountain Building

    Subduction zone

    Continental collision

    Fault-block mountains

    GEOL131: Crustal Deformation: Mountain Building

  • New TermGEOL131: Crustal Deformation: Mountain BuildingACCRETIONARY WEDGE: Sediment & rock scraped off subducting plate onto overriding plate

  • Mountains Built at Subduction Zones

    Volcanic arc

    Uplifted accretionary wedge

    Uplifted igneous intrusions

    Accreted volcanic island arc

    GEOL131: Crustal Deformation: Mountain Building

  • Mountains Built at Subduction Zones: Volcanic arcGEOL131: Crustal Deformation: Mountain Building

  • Mountains Built at Subduction Zones: Uplifted accretionary wedgeGEOL131: Crustal Deformation: Mountain Building

  • Mountains Built at Subduction Zones: Uplifted accretionary wedgeGEOL131: Crustal Deformation: Mountain Building

  • Mountains Built at Subduction Zones: Uplifted igneous intrusionsGEOL131: Crustal Deformation: Mountain Building

  • Mountains Built at Subduction Zones: Accreted Volcanic Island ArcGEOL131: Crustal Deformation: Mountain Building

  • Mountains Built by Continental CollisionsGEOL131: Crustal Deformation: Mountain Building

  • Mountains Built by Continental CollisionsGEOL131: Crustal Deformation: Mountain BuildingContinental escape: blocks of continental crust are pushed away from a continental collision zone

  • Mountains Built by Continental CollisionsCompressional stress

    Folding

    Reverse and thrust faultingGEOL131: Crustal Deformation: Mountain Building

  • Fault Block MountainsTensional stress

    Normal faultingGEOL131: Crustal Deformation: Mountain Building

  • Fault Block MountainsGEOL131: Crustal Deformation: Mountain BuildingGrand Tetons

  • End of Chapter

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