brittle structures

Question 1

–The
permanent change that occurs in a
solid material due to the growth of
fractures and/ or due to sliding on
fractures.

Answer 1

Brittle deformation

Question 2

• A band of finite width in which slip is distributed among many smaller discrete brittle faults,
  and/or in which the fault surface is bordered by pervasively fractured rock.

Answer 2

Brittle fault zone

Question 3

A single surface on which movement occurs specifically by brittle deformation mechanisms.

Answer 3

Brittle fault-

Question 4

A deformation process that involves distributed fracturing, crushing, and frictional sliding of grains or
of rock fragments.

Answer 4

Cataclasis-

Question 5

Verb: to break or snap apart. Noun: a fracture whose displacement does not involve shear displacement
(i.e., a joint or microjoint).

Answer 5

Crack-

Question 6

Broad sense: a surface or zone across which there has been measurable sliding parallel to the surface.

Answer 6

Fault-

Question 7

A band in which there are many parallel or subparallel fractures. If the fractures are wavy, they

may anastomose with one another. Note: The term has a somewhat different meaning in the context of ocean-
floor tectonics.

Answer 7

Fracture zone

Question 8

A general term for a surface in a material across which there has been loss of continuity and,
therefore, strength. Fractures range in size from grain-scale to continent-scale.

Answer 8

Fracture-

Question 9

A microcrack that has cemented back together. Under a microscope, it is defined by

Answer 9

Healed microcrack-

Question 10

A natural fracture which forms by tensile loading, i.e., the walls of the fracture move apart very
slightly as the joint develops. Note: A minority of geologists argue that joints can form due to shear loading.

Answer 10

Joint-

Question 11

A very small fracture of any type. _____________ range in size from the dimensions of a
single grain to the dimensions of a thin section.

Answer 11

Microfracture-

Question 12

_________________________ range in size from the dimensions of a single grain to the
dimensions of a hand-specimen.

Answer 12

Microjoint-

Question 13

• A macroscopic fracture that grows in association with a component of shear parallel to
  the fracture. Shear fracturing involves coalescence of microcracks.

A surface that originated as a joint but later became a surface of sliding.

• A shear fracture.
• A region of finite width in which ductile shear strain is significantly greater than in the
  surrounding rock. Movement in shear zones is a consequence of ductile deformation mechanisms
  (cataclasis, crystal plasticity, diffusion).

Answer 13

Shear fracture

-* Shear joint-

• Shear rupture
• Shear zone

Question 14

– the line representing the
intersection of the fracture with the surface of a
rock body.

– the line that separates the
region of the rock which has fractured from the
region that has not fractured.

– the point at which the fracture
trace terminates on the surface of the rock

Answer 14

Fracture trace

• Fracture front
• Fracture tip