Deformation Flashcards
Define Stress
Forces applied to a rock by Earth movements or the mass of overlying rock
Define Strain
A change in shape or volume of a body as a result of applied stress
What are four factors which affect a rocks behaviour?
Temperature, Time, Pressure, Strength
What does SWAN stand for?
Synclines Wider on downthrown side and Anticlines are Narrower
What are three features which can be used as indicators of the direction of movement of a fault?
Displacement of strata, Drag folds, Slickensides
What are six fault indicators which don’t indicate direction of movement?
Fault scarp, Fault controlled valleys, Fault breccia, Fault gouge, Mineral veins, Mylonite
What are the three folding mechanisms?
Buckling, Shear folding, Flexural slip
Define Parallel Folds
Limbs and hinge both have the same thickness along its length. The rock has buckled to allow it to take up the strain
Define Similar Folds
The hinge gets thicker and the limbs get thinner. The rock has sheared to allow it to take up the strain (shear folding)
% Shortening =
(Original length - New length / Original length) x100
What does ASSO stand for?
Antiform plunges Same direction as closure Syncline plunges Opposite direction as closure
How is axial planar cleavage produced?
Produced by the recrystallisation of clay minerals during regional metamorphism
What does TODS stand for?
Tick is On Downthrown Side of the fault
When will a vertical feature show offset?
If it moves horizontally
When will a dipping feature show offset?
It always shows horizontal offset even if the fault moves vertically
