Transcript permanent, rock breaks Stress vs. Strain Rheology Deformation

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
Rheology
Force
Stress vs. Strain
Deformation
Ductile
Brittle
How Rocks Become Deformed
1.
compression forces
2.
tensional forces
3.
shearing forces
Rheology
Force
Stress vs. Strain
Deformation
Rheology
Force
Stress vs. Strain
Deformation
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
Anticline
Axial plane
Bill Evarts
Fig. 10.11
Asymmetric Folds
Breck Kent
Overturned Folds
Phil Dombrowski
Fig. 10.1
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
Horst
Horst
Graben
Wildrose Graben, Southern California
NASA/TSADO/Tom Stack