DEFORMATION OF THE EARTHS CRUST Types of Deformation 1.folds 2.faults
Deformation 1. Elastic – nonpermanent, rock returns to original shape 2. Ductile – permanent, rock flows or bends 3. Brittle – permanent, rock breaks
Stress vs. Strain Rheology Deformation Force
Ductile Brittle
How Rocks Become Deformed 1.compression forces 2.tensional forces 3.shearing forces
Stress vs. Strain Rheology Deformation Force
Stress vs. Strain Rheology Deformation Force
Folded Rocks 1.due to compressional forces 2.types of folds i.monocline ii.anticlines iii.synclines
Monocline, WY George Davis
Folded Rocks 3. anatomy of a fold i.limbs ii.axial plane iii.plunge
Folded Rocks 2.types of folds iv.overturned v.asymmetrical
Bill Evarts Axial plane Anticline Fig
Breck Kent Asymmetric Folds
Phil Dombrowski Fig Overturned Folds
Folded Rocks 2.types of folds vi.domes vii.basins
Folded Rocks 2. effects of folds i.mountain building (orogenies)
Fractured Rocks 1.How a rock breaks i.joints
Fractured Rocks 1.How a rock breaks i.joints ii.faults
Anatomy of a fault i.head wall (or hanging wall) ii.foot wall iii.fault plane
Anatomy of a fault iv.strike & dip
Types of Faults Strike-slip faults have movement that is predominantly horizontal and parallel to the strike of the fault plane –A viewer looking across to the other side of a right-lateral strike-slip fault would observe it to be offset to their right –A viewer looking across to the other side of a left-lateral strike-slip fault would observe it to be offset to their left Oblique-slip faults have movement that with components parallel to both the strike and dip of the fault plane Right-lateral San Andreas Fault
Effects of faulting i.horsts and grabbens Graben Horst
Wildrose Graben, Southern California
NASA/TSADO/Tom Stack