Tidl. eks Flashcards
Name a primary structure
Cross-bedding
What is stress?
It is force per unit area
What is brittle deformation typical of?
Low temperatures and pressures in the upper crust
Normal faults usually form in stressystems in which:
sigma 2 i horizontal (and 3)
sigma 1 is vertical
A later fault will have the following relationship to an earlier fault:
The later fault will cut the older fault
The length of a fault is usually roughly proportional to:
Maximum displacement on the fault
What are components of deformation?
Rotation, translation and strain
What is characteristic of homogeneous strain?
Straight and parallel lines remain straight and parallel
What is true about relationship between strain and stress?
Strain CAN be proportional to stress (elastic)
What effect does fluids have on rock strength?
Fluids decrease rock strength
Where would cataclastic rocks generally tend to develop?
Along faults in the upper crust
What types of fault systems tend to act as precursors to the separation of plates and the development of oceanic crust?
Rifts
What fault geometries are characteristic of horsts and grabens?
Conjugate normal faults
Why are earthquakes more likely to occur in the upper crust than in the lower crust?
The upper crust is dominated by brittle deformation
What is true about rheology and rocks?
All rocks can flow
Where do damage zones characteristically develop?
Around fault plantes
Why is it important to show a hammer or person on field photographs?
It shows the scale of the structures.
Geometric descriptors of geological structures include
Size, shape and orientation
Normal faults usually form in stress systems in which:
sigma 2 is horizontal, sigma 3
sigma 1 is vertical
Relay ramps occur at which locations?
Between two normal faults that step in map view
Which shape can be used to represent stresses and strain?
Ellipsoid
What is characteristic of ductile deformation?
There is strain without macroscopically visible fractures
Where can rocks be strongest?
The mantle, dry rocks are the strongest
What is the best way to quantify the strain across a rift system?
Amount of extension?
What cannot be used to infer the orientation of present day stresses?
Gravity and magnetic data?
What is true about perfectly viscous fluids?
Strain rate proportional to applied stress, permanent deformation, strain is time-dependent
