Foliation

Question 1

Describes the arrangement of any kind of sub-parallel, closely space, and low-cohesion surfaces.

Answer 1

Foliation

Question 2

These are generally regularly spaced surfaces that may split into leaf-like planar elements other than bedding.

Answer 2

Foliation

Question 3

Meaning of Folia in Latin

Answer 3

Leaf

Question 4

What are three structures that define Foliations:

Answer 4

1. Compositional Layering in Metamorphic Rocks
2. Sedimentary Planes
3. Oriented Mineral Grains along successive planes

Question 5

Foliations in an area with different
ages are designated (Sn), where n
indicates the __________ ____.

Answer 5

Relative Age

Question 6

The Development of foliation depends on:

Answer 6

1. Composition of the Rock
2. Temperature of Burial
3. Depth of Burial

Question 7

What are the three mechanisms involved in the development of foliations?

Answer 7

1. Mechanical Rotation
2. Solution/Precipitation
3. Crystallization and Recrystallization

Question 8

All of the mechanisms involved in the development of foliations tend to produce a _________ structure.

Answer 8

Planar

Question 9

Foliation Development is related to?

Answer 9

Metamorphic Facies

Question 10

Foliation Development starts from?

Answer 10

Diagenesis

Question 11

Two factors that are also important in Foliation Development

Answer 11

Lithology and Mineralogy

Question 12

It is a mineral group important in forming cleavage or schistosity

Answer 12

Phyllosilicates

Question 13

A secondary fabric element, formed under low-Temp conditions, that imparts on the rock a tendency to split along planes.

Answer 13

Cleavage

Question 14

Cleavage development removes ___________ ______.

Answer 14

Soluble Grains

Question 15

In argillaceous sandstone quartz is
preferentially dissolved, and ________ is concentrated.

Answer 15

Clay

Question 16

Where does clay concentrate into?

Answer 16

Domains

Question 17

What do domains contain, where clay plates or laths become preferentially oriented and concentrated?

Answer 17

Selvages

Question 18

A type of cleavage that forms mostly in sedimentary rocks that have been subjected to a tectonic differential stress.

Answer 18

Disjunctive Cleavage

Question 19

In the process of Disjunctive Cleavage formation, _____________ is also goin on.

Answer 19

Dissolution

Question 20

The result of Dissolution in the rocks that are widely spaced.

Answer 20

Prominent Striping

Question 21

Mineral Grains and collapses of pore space result in?

Answer 21

1. Accentuation
2. Reworking of Bedding Planes

Question 22

A series of dissolution surfaces

Answer 22

Cleavage Domains

Question 23

Thin slabs of rock

Answer 23

Microlithons

Question 24

These are heterogeneously distributed lamellae where the fabric and mineralogy of the host rock have been altered

Answer 24

Cleavage Domains

Question 25

Thin Planar regions along which the rock splits

Answer 25

Cleavage Domains

Question 26

This can also form due to the pressure solution in the formation of disjunctive cleavage

Answer 26

Stylolitic Cleavage or Pressure Solution Cleavage

Question 27

Disjunctive Cleavage is formed in _____-____, and _____ __________ grade rocks

Answer 27

Fluid-rich and Low Metamorphic

Question 28

A type of cleavage characterized by a low-temperature tectonic fabric formed due to the shortening of clay-rich sediments like mudstones.

Answer 28

Pencil Cleavage

Question 29

Pencil Cleavage typically forms in __________ _______.

Answer 29

Folded Rocks

Question 30

A type of cleavage that have a strong dimensionally preferred orientation of phyllosilicates in a very clay-rich rock.

Answer 30

Slaty Cleavage

Question 31

A type of cleavage that tends to be smooth and planar.

Answer 31

Slaty Cleavage

Question 32

A type of cleavage created when an earlier foliation is folded and will be overprinted by a new foliation with a new orientation.

Answer 32

Crenulation Cleavage

Question 33

The small, regular crinkle folds in crenulation cleavage are most commonly _____________.

Answer 33

Asymmetric

Question 34

A type of cleavage where the clay and illite in a pelitic rock react to form white mica and chlorite, and growing with a strong preferred orientation.

Answer 34

Phyllitic Cleavage

Question 35

What is the Metamorphic Facies reached where phyllitic cleavage starts to form?

Answer 35

Lower Greenschist Facies

Question 36

A foliation where the mica grains grow larger and become easily discerned with a naked eye, and the planar fabrics become coarser that tends to be wavy and discontinuous.

Answer 36

Schistosity

Question 37

What are the Metamorphic Facies reached where schistosity forms?

Answer 37

Upper Greenschist Facies to Lower Amphibole Facies

Question 38

A foliation where compositional layering may occur due to recrystallization that forms bands parallel to the direction of stress.

Answer 38

Gneissic Foliation

Question 39

A foliation characterized by alternating layers of light and dark-colored minerals

Answer 39

Gneissic Foliation

Question 40

Gneiss derived from a Sedimentary Protolith

Answer 40

Paragneiss

Question 41

Gneiss derived from a Igneous Protolith

Answer 41

Orthogneiss

Question 42

A special type Gneiss that contains relatively large feldspar clasts floating in a finer-grained matrix

Answer 42

Augen Gneiss

Question 43

A foliation formed by the accumulation of large shear strain in ductile fault zones. High strains flatten objects and thin layers.

Answer 43

Mylonitic Foliation

Question 44

A foliation related to transposed layering and gneissic banding, but the distance between the foliation domains is smaller, typically on the mm to cm scale.

Answer 44

Mylonitic Foliation

Question 45

Zones that are typically found in shear zones or thrust zones that involve large (kilometer scale or more) displacements.

Answer 45

Mylonite Zones

Question 46

A foliation in folded rocks is subparallel (ideally, parallel) to the axial plane in the fold hinges produced by the same deformation event.

Answer 46

Axial Plane Foliation

Question 47

The change of angular relationship between foliation and bedding across lithological boundaries

Answer 47

Cleavage Refraction

Question 48

A feature where an Axial plane foliations typically display a radiating pattern within the fold.

Answer 48

Foliation Fan

Question 49

A convergent or divergent feature, depending on whether the foliation converges towards the core or the convex side of a fold, respectively.

Answer 49

Foliation Fan

Question 50

True or False? Both convergent and divergent fans may coexist in a folded multi-layer

Answer 50

True

Question 51

A concept routinely used to determine which limb of an incompletely exposed fold a particular outcrop belongs to, even if hinges cannot be seen.

Answer 51

Foliation-Bedding Angular Relation

Question 52

True or False? Foliation is a planar fabric element that originates from sedimentary and magmatic processes (primary fabric) and ductile deformation (secondary fabric).

Answer 52

True

Question 53

True or False? Most foliations form parallel to or at a high angle to the shortening direction.

Answer 53

False, it forms perpendicular

Question 54

True or False? Cleavages are commonly found to closely define the axial surface of related folds.

Answer 54

True

Question 55

True or False? Pressure solution does not remove large volumes of rock during cleavage formation.

Answer 55

False, pressure solution removes volume

Question 56

True or False? Permineralization of minerals is involved in the formation of schistosity, gneissic and mylonitic foliations.

Answer 56

False, it should be Recrystallization