Metamorphic Petrology Flashcards
(139 cards)
1
Q
is a response to changes in temperature and/or pressure over time from some initial state
A
Metamorphism
2
Q
results from increasing temperature and/or pressure conditions over time
A
Prograde Metamorphism
3
Q
Agents of Metamorphism
A
Heat
Pressure
Chemically Active Fluids
4
Q
Most important agent of Metamorphism
Why?
A
Heat
It provides the energy to drive the chemical changes that result in recrystallization of minerals.
5
Q
altered rocks that occur in contact metamorphic zone
A
Aureole
6
Q
results from decreasing temperature and/or pressure so that lower temperature/pressure mineral assemblages develop that overprint earlier peak tempertature/pressure mineral assemblages
A
Retrograde Metamorphism
7
Q
occurs when rocks immediately surrounding a molten igneous body and altered from their original state
A
Contact Metamorphism
8
Q
this occurs when hot, ion-rich fluids circulate through fissures and cracks in rock
A
Hydrothermal Metamorphism
9
Q
chemical alteration of rock
A
Metasomatism
10
Q
Where is hydrothermal metamorphism mostly occur?
A
along the axis of Mid-ocean ridge system
11
Q
at what temp and depth does metamorphism begin
A
200C of about 8km
12
Q
tends to occur where massive amounts of sedimentary or volcanic material accumulates in a subsiding basin
A
Burial Metamorphism
13
Q
occurs during mountain building when large segments of Earth’s crust are intensely deformed along convergent plate boundaries
A
Regional Metamorphism
14
Q
results from increases in lithostatic stress induced by deep burial of rock and produces non-foliated textures
A
Burial metamorphism
15
Q
uncemented claylike material found in shallow fault zone
A
Fault gouge
16
Q
deformation associated with fault zones occurs at great depth and at high temperature
A
Cataclastic Metamorphism
or
Metamorphism Alone Fault Zones
17
Q
occurs when high-speed projectiles strike at Earth’s surface
A
Impact/Shock Metamorphism
18
Q
products of meteor impacts
A
Impactites
19
Q
directed force of some magnitude applied over an area
A
Stress
20
Q
change induced by stress
A
Deformation
21
Q
force oriented
a. perpendicular to the inclined plane
b. parallel
A
a. Normal Force
b. Shear Force
22
Q
A. occurs where forces are directed towards a point or a plane
B. occurs where forces are directed away a point or a plane
C. occurs where forces are oriented parallel to the plane
A
Compression
Tension
Shear
23
Q
_______________ is parallel to two principal stress axes and normal to the third axis
A
Principal Plane
24
Q
occurs when all three principal stress axes of equal magnitude
A
Uniform Stress
25
refers to the uniform compressive force directed radially inward by the surrounding mass of water
Hydrostatic Stress
26
refers to a uniform force exerted radially inward due to the mass of the surrounding rock
Lithostatic Stress
27
occurs when at least one principal stress has magnitude not equal to the other principal stress
Non-uniform/Anisotropic/Deviatoric Stress
28
also known as strain, indicates a change in shape from some initial form
Distortion
29
occurs when strain is equal throughout the rock body so that parallel lines remain parallel, perpendicular lines remain prependicular and circles flatten to become ellipses
Homogenous Strain
30
indicates a change in volume
Dilation
31
occurs when strain intensity varies within a rock body
Heterogenous Strain
32
also known as displacement, means that an object has moved from one point to another point
Translation
33
infers that an object has moved in a circular arc about an axis
Rotation
34
development from an initial to final state
Kinematic Strain
35
refers to one or more intermediate strain steps describing separate strain conditions
Incremental Strain
36
infers that no rotation of the incremental strain axes occurred from an initial to final strain rate and this strain produces pure shear
Coaxial Strain
37
structures in which the X, Y and Z axes do not rotate during progressive strain
Pure Shear (Irrotational Strain)
38
is a rotational strain in which the strain axes rotate through time
Non-coaxial Strain
39
strain axes do not remain parallel during progressive deformation
Simple Shear
40
is a combination of pure shear and simple shear
General Shear
41
refers to how materials respond to stress
Rheology
42
occurs when a body is deformed in response to astress but returns to its original shape when the stress is removed
Elastic Deformation
43
is an irreversible strain without visible fractures, although microfracturing can occur
Plastic Deformation
44
creates visible fractures in response to stress
Rupture Deformation
45
a temporary reversible strain in which a linear relationship exists between stress and strain
Hookean Behavior
or
Elastic Behavior
46
is a constant of proportionality that describes the slope of the line
Young's Modulus
47
is an irreversible strain that occurs without visible (mesoscopic) fractures
Plastic Behavior
48
in which mesoscopic ductile behavior is facilitated by microscopic fracturing and frictional sliding
Cataclastic Flow
49
a high temperature and high pressure process that involves the flow of material through the crystals
Diffusional Mass Transfer
50
processes create adjustment in deformed crystal lattice structures
Crystal Defect
51
achieved by bending the lattice through gliding along weak planes within crystalline structures
Crystal Plasticity
52
common in calcite and feldspar minerals
Mechanical twinning
53
common in micas and other platy minerals such as clays
Kinking
54
permanent, irreversible deformation characterized by the development of visible fractures and loss of cohesion between rock particles
Brittle Behavior
55
is the depth within Earth where behavior changes from brittle to ductile behavior. This boundary can be generalized as existing at depths approx 10-20km and temp of approx 300C
Brittle-Ductile Behavior
56
describes the resistance of rocks to flow
Competency
57
rocks that commonly display ductile behavior and include rock salt, shale, siltstone, slate, phyllite and schist
Incompetent Rocks
58
refers to the amount of stress necessary to induce failure
Strength
59
are brittle structures that develop by rupturing either previously intact rock or pre-existing weak surfaces in rock
Fractures
60
are fractures with minimal displacement
Joints
61
are fractures that involve displacement
Fault
62
are fractures through which fluids flow, producing one or more secondary minerals that precipitate from solution
Veins
63
arrays are produced by high strain rate events that blast rock apart dye to high pressures
Non-systematic Vein
64
fluids that precipitate as secondary minerals in veins develop blocky or fibrous textures
Vein Filling
65
rocks that commonly display brittle behavior and include metaquartzite, granite, gneiss, quartz, sandstone, basalt, gabbro and diorite
Competent Rocks
66
minerals are equant and may display euhedral crystal faces indicating growth within an unimpeded open space
Blocky or Sparry
67
arrays consist of veins that display orientations suggesting a common origin in response to directed stress
Systematic Vein
68
displayes a linear, acicular character suggesting that vein growth was incremental in response to fracture in response to fracture width increases
Fibrous Veins
69
form by the plastic bending of rock layers without displaying mesoscopic brittle behavior
Folds
70
are relatively straight layers separated by a high curvature region of the hinge
Limbs
71
is a point of maximum curvature separating two limbs
Hinge
72
is an imaginary line connecting a series of hinge points along the strike of the fold
Hinge Line
73
is an imaginary plane connecting a series of hinge line
Axial Surface or Axial Plane
74
is the point at which the sense of curvature changes from one fold to another
Inflection Point
75
folds characterized by a convex-upward structure
Antiform
76
folds structures with concave-upward shapes
Synform
77
consist of two limbs that dip towards the hinge
Syncline
78
are circular to oval structures in which rock layers dip towards the center
Basin
79
are circular oval structures in which rock layers dip away from the center
Dome
80
consist of two limbs that dip away from the hinge
Anticline
81
also known as texture, refers to the geometric arrangement of grains within a rock
Fabric
82
infers that the structure are continuous on a mm scale so that no undeformed parts of the rock remain
Continuous Fabric
83
means that visible spacing exists between fabric elements so that both deformed and undeformed parts of the rock are visible
Spaced Fabric
84
infers that no preferred orientation of component elements exists
Random Fabric
85
means that rock elements are aligned in a predicatable manner
Preferred Fabric
86
refers to the tendency of rocks to break along sub-parallel surfaces
Cleavage
87
consists of parallel foliations oriented nearly perpendicular to the maximum compressive stress, and converging towards the inner arc of the fold hinge area
Axial Planar Cleavage
88
form by the intersection of two planar fabrics
Intersection Lineations
89
are linear features produced by geological structures
Form Lineations
90
is an intersection lineation marked by the development of elongate shards
Pencil Cleavage
91
are linear features that occur as a result of a secondary cleavage imposed upon a fine-grained rock that experienced an earlier cleavage
Crenulation Lineations
92
develop as elongated mineral or rock grains that define a linear fabric
Stretching Lineations
93
lineations refer to vein mineral fibers that precipitate on rock surfaces via crac
Slip or Fiber
94
refers to the size, shape, orientation and intergranular relationships of the rock's constituents
Texture
95
nearly equal diameters in all directions and assume forms approximated by spheres or cubes
Equant Grains
96
contain at least one direction in which the grain diameter is not equal to the other grain diameter
Inequant Grains
97
large relict grains from the protolith that have experienced deformation but have retained their original composition
Porphyroclast
98
large grains that have experienced neocrystallization and growth in response to favorable temperature and pressure conditions during metamorphism
Porphyroblast
99
oval-shaped feldspar porphyroclasts that resemble the shape of an eye and are particularly common in gneisses, whereas flaser are composed of quartz
Augen
100
occur when no preferred orientation of inequant grains is visible
Random Grain Orientation
101
occurs when inequant grains are oriented sub-parallel to one another and can produce lineations and foliations
Preferred Grain Orientation
102
refers to any planar arrangement of mineral grains within a rock
Foliation
103
refers to closely spaced, flat sufaces along which rocks split into thin slabs when hit with a hammer
Rock or Slaty Cleavage
104
very common foliation defined by the sub-parallel arrangement of macroscopic platy minerals such as phyllosilicated in closely spaced metamorphic minerals
Schistosity
105
a foliation characterized by the arrangement of minerals into distinct color bands
Gneissic Textures
106
Gneiss with
a. Igneous Protolith
b. Sedimentary protolith
a. Orthogneiss
| b. Paragneiss
107
a very fine-grained foliated rock composed of minute mica flakes that are too small to be visible
Slates
108
most often generated by the low-grade metamorphism
Slate
109
mineral constituent of ___ shale
a. Black
b. Red
c. Green
a. organic matter
b. Iron Oxide
c. Chlorite
110
fine-grained foliated metamorphic rock with a pervasive cleavage produced by alignment of micas
Phyllite
111
medium to coarse grained metamorphic rocks in which platy minerals predominate
Schist
112
produced by dynamothermal metamorphism at convergent plate boundaries with temperatures >300C
Schist
113
medium to coarse grained banded metamorphic rocks in which granular and elongated minerals predominate
Gneiss
114
is a result of mineral segregation into separate, typically light and dark colored layers
Banding
115
lack metamorphic layering as defined by preferred mineral orientations
Non-foliated Texture
116
coarse, crystalline metamorphic rocks rich in calcite and/or dolomite
Marbles
117
fine grained, non-foliated fabric that develops by contact metamorphism
Hornfelsic Texture
118
form by high temperature (>800C) and high pressure (>10kbar, ~33km depth) metamorphism
Granulites
119
very high pressure, high temperature rocks that develop principally from basalt/gabbro protoliths
Eclogite
120
fine-grained, foliated rocks produced in the ductile shear zones of the lower crust and mantle
Mylonite
121
composed of fractures, angular particles that form in response to the brittle crushing of grains during deformation in upper crustal fault zones
Cataclastic Trxtures
122
are classified on the basis on the percentage of matrix material to porphyroclasts
Mylonites
123
are described with respect to the relative percentaged of larger clasts and finer matrix and their degree of cohesion
Cataclastix Texture
124
Cataclastic rocks that lack cohesion are called
Breccia
125
consists of the region bounded by two isgrad lines
Metamorphic Zone
126
are linedrawn on geological maps that mark the first appearance of the particular index mineral
Isograds
127
bounded by the chlorite and biotite isograds
Chlorite Zone
128
marking the first appearance of Almandine and Biotite isograd
Biotite Zone
129
Marks the first appearance of Staurolite and Almandine isograd
Almandine Zone
130
Marks the the first appearance of the higher temperature mineral kyanite and staurolite isograd
Staurolite Zone
131
occurs between kyanite and sillimanite isograds that mark their first appearance
Kyanite Zone
132
the highest temperature zone in Barrovian Zone
Sillimanite Zone
133
are distinctive mineral assemblages in metamorphic rocks that form in response to a particular range of temperature and/or pressure conditions
Metamorphic Facies
134
What is the temperature, pressure and depth of the ff
a. Albite-Epidote Hornfels Facies
b. Hornblende Hornfels Facies
c. Pyroxene Hornfels Facies
d. Sanidinite Hornfels Facies
a. <450C, <2kbar, 6km depth
b. 450-600C, <2.5kbar, <8km
c. 600-800C, <2.5kbar, <8km
d. >800C, <2.5kbar, <8km
135
What is the temperature, pressure and depth of the ff
a. Zeolite Facies
b. Prehnite-Pumpellyite facies
c. Greenschist Facies
d. Amphibolite Facies
e. Granulite Facies
a. 150-300C, <5kbar, 15km
b. 250-300C, <6kbar, 20km
c. 350-550C, 3-10kbar, 10-30km
d. 550-750C, 4-12kbar, 12-40km
e. 700-900C, 3-15kbar, 10-50km
136
What is the temperature, pressure and depth of the ff
a. Blueschist Facies
b. Eclogite Facies
a. 150-500C, 4-20kbar, 13-66km
| b. 400-900C, 12-25kbar, 40-82km
137
Key mineral/s in
a. Greenschist
b. Blueschist
c. Eclogite
a. Chlorite, Actinolite, Epidote
b. Glaucophane
c. Garnet, Omphacite, Jadeite
138
is a sequence of facies that occurs across a metamorphic terrane due to differences in pressure and temperature conditions
Metamorphic Facies Series
139
Geothermal Gradient of the ff
a. Contact Facies Series
b. Buchan Facies Series
c. Barrovian Facies Series
d. Sanbagawa Facies Series
e. Franciscan Facies Series
a. >80C/km
b. 40-80C/km
c. 20-40C/km
d. 10-20C/km
e. <10C/km
