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 forethrust Backthrust Basal Detachment Basement

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

Canadian Rockies Mountain Front

Faults of the Canadian Rockies

Bow and arrow rule

Distribution of Shortening

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

E W Rundel Thrust Pz limestone Jur-K Kootenay Fm.

Detached folds- Jura Mts. Salt Detachment 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 patterns Complicated 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 B B D D