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Series1

Thrust Faults

What kind of fault is it? Precambrian

Paleozoic

How Thrust belts form

Thrust Belt in a Sandbox

Parts of a Thrust-Belt

Components of a thrust belt

forethrustBackthrust

Basal DetachmentBasement

Origin of Foreland Basins

Asia Topography

Sevier Thrust Belt, Wyoming

•Complex Imbricate fan

•Basement involved def.

•Thin-skin def.

Appalachians

Sequence of deformation

Forward propagation of deformation front

1

1

1

1

2

2

2

3

3

Canadian Rockies Mountain Front

Faults of the Canadian Rockies

Bow andarrow rule

Distribution of Shortening

Mt. Yamnuska, Canadian Rockies- McConnell Thrust

Mt. Yamnuska, Canadian Rockies- McConnell Thrust

Cretaceous foreland basin strata

Cambrian limestone

Dev. Limestone

Palliser Fm.

Cretaceous, Belly River Gp.

Lewis

Thrust

Folded Paleozoic Rocks of the Sawback ranges

Front Ranges

E W

Front Ranges

E W

Rundel Thrust

Pz limestone

Jur-K Kootenay Fm.

Detached folds- Jura Mts.

SaltDetachment surface

Calico Bluff, Eagle, AK

Pop-up Structure- A Faulted Fold

Thrust Breaching the Surface- Landers, CA

Geometry of Thrust Sheets

The shape of the fault plane determines the geometry of the folds

The hanging wall conforms to the shape of the footwall

Fault-bend-fold

Progression

Thrust belt movie

Termination of fault-related fold

Fault-related Folding

Duplex

Thrust belt movie

Duplex Spacing

Duplex Structure in thin-bedded sandstones and shales

Fault-propagation

fold

The fault grows as displacement grows

Map patternsComplicated due to erosion of the thrust sheets

Mechanical Paradox of Thrust Sheets

• Stress required to move a thrust sheet is larger than the strength of the rock

• Like trying to push a Jell-O block across the table

Solutions:

1. Reduce Basal Friction High fluid Pressure

2. The sheet does not move all at once

Role of Fluid Pressure

Like pushing a wrinkle out of a rug

Critical Wedge Growth

Keystone thrust fault, southern Nevada

BBDD