Transcript Mountain Belts and the Continental Crust

Crustal Deformation and
Mountain Building
Behavior of rocks to stress
& strain
• Elastic
– Elastic limit
• Plastic
• Brittle
Stress
Strain
FOLDS
• Anticline vs. syncline
– Hinge line (axis)
– Limb
– Axial plane
• Plunging fold
• Structural dome
• Structural basin
FOLDS
• Interpreting folds
– Open fold
– Isoclinal fold
– Overturned fold
– Recumbent fold
Faults
• Fractures in rock
• Normal Faults
• Reverse fault
– Thrust fault- low angle reverse fault
• Strike-Slip fault
– Left-lateral vs. right-lateral
Introduction
• Mountain
• Major mountain belts
• Mountain range
Characteristics of Major
Mountain Belts
• Size and Alignment
• Along continental margin
• Long, arcuate chains
• Ages of Mountain Belts and Continents
–Youngest tend to be higher
–Himalayas vs Appalachians
–Craton- Oldest Continental Crust
• Precambrian Shield
Characteristics of Major
Mountain Belts
• Patterns of Flooding and Faulting
– Fold and Thrust Belts
• Crustal Shortening
• Crustal Thickening
• Metamorphism and Plutonism
• Normal Faulting
Rifting
Subduction
Accretionary wedge
Volcanism
Plutonism
Orogeny
Subduction
Collision
Crustal Shortening &
Thickening
Major Orogeny
Evolution of a Mountain Belt
• Accumulation Stage of Sediments
– Accumulation in an Opening Ocean Basin
– Accumulation along a Convergent
Boundary
• Graywackes
• Magmatic Arc
• Mountain Building Event- Orogeny
Evolution of a Mountain Belt
• The Uplift and Block-faulting Stage
– Isostacy
• Isostatic Adjustment
– Normal Faulting
• Fault-block Mountain Range
The Growth of Continents
• Crust added by accumulation & igneous
activity
• Suspect and Exotic Terranes
– Suspect terrane
– Accreted terrane
• Exotic terrane
The Wilson cycle (named after J. Tuzo Wilson, one of the fathers
of plate tectonics) refers to the cycle of ocean basin formation by
rifting and seafloor spreading followed by ocean basin
destruction and mountain building by subduction.