metamorphic rocks

Question 1

What causes metamorphic rocks to be formed

Answer 1

Heat and Pressure, however fluid also plays an important role

Question 2

How does igneous and sedimentary rock formation processes, differ from metamorphic.

Answer 2

Metamorphic takes place deep below the earths surface where we can’t view it.

Question 3

Test questions**** How does heat and temperature effect metamorphism

Answer 3

The temperatures and pressures are much higher than on the earths surface. HOWEVER it does not cause melting or magma, thus the temperature and pressure are below the conditions that cause for melting. High Grade starts at 600 degrees C

Question 4

Test question** What state do metamorphic rocks remain in?

Answer 4

Solid, and metamorphic rocks change off the different protoliths they have or the different (Starting rocks)

Question 5

What are high grade metamorphic rocks** test question

Answer 5

Rocks that are formed under high temperature and high pressure

Question 6

What are the categories of metamorphic rocks

Answer 6

Foliated and Non-foliated. They differ based off the protolith

Question 7

What is contact metamorphism

Answer 7

when rising magma creates a batholith the zone just outside of the magma gets altered by the heat.

Question 8

Formation of cross bending **test question (sedimentary rocks)

Answer 8

direction of flow in water determines the direction of the Dip of Lee slope. Symmetrical ripples and asymmetrical ripples.

Question 9

Define lithostratic or confining pressure and what are its effects

Answer 9

Most metamorphic processes take place deep underground, inside the earth’s crust. During metamorphism, protolith chemistry is mildly changed by increased temperature (heat), a type of pressure called confining pressure, and/or chemically reactive fluids.

Question 10

define and explain differential stress or directed pressure

Answer 10

modifies rock at a mechanical level, causes alignment of elongated or platy minerals and growth of new minerals in same direction or causes the identification of Foliation.

Question 11

Define foliation***possible test question

Answer 11

Foliation is a term used that describes minerals lined up in planes. Certain minerals, most notably the mica group, are mostly thin and planar by default. Foliated rocks typically appear as if the minerals are stacked like pages of a book, thus the use of the term ‘folia’, like a leaf

Question 12

going from low grade to high grade changes what

Answer 12

crystal size, and increasing coarseness of foliation.

Question 13

Foliated slate, low grade

Answer 13

fine grained, clay rich, protolith= shale
elongated and platy minerals aligned and compressed
breaks smoothly along foliation planes
cannot see micas and therefor light is not reflected so the rock is not shiny

Question 14

Foliated metamorphic rock: phyllite

Answer 14

micas start growing perpendicular to stress, shiny surface due to micas
fine grained.

Question 15

Define micas

Answer 15

a

Question 16

Foiliated metamorphic rock: Shists

Answer 16

micas growing parallel 
 coarser than phyllite, will break along cleavage planes
 often folded (i.e. higher pressures)

Question 17

Foliated metamorphic rock: gneiss

Answer 17

• minerals segregated into light (quartz and feldspar) and dark (biotite and amphibole) bands
  can be tightly folded
  coarser than schist, won’t break along foliation planes

Question 18

Foliated Metamorphic Rocks: migmatite

Answer 18

partial melting in the core of mountain belt
mixture of igneous (granite) and metamorphic (gneiss) rock
transitional rock from metamorphic to igneous

Question 19

Define Un-foliated metamorphic rock

Answer 19

Non-foliated textures do not have lineations, foliations, or other alignments of mineral grains. Non-foliated metamorphic rocks are typically composed of just one mineral, and therefore, usually show the effects of metamorphism with recrystallization in which crystals grow together, but with no preferred direction. The two most common examples of non-foliated rocks are quartzite and marble

Question 20

Non-foliated rocks: Quartzite

Answer 20

non-foliated, recrystallized sandstone
composed almost purely of quartz (SiO2)
some sedimentary structures (bedding, cross-bedding) survive the recrystallization
contact or regional metamorphism

Question 21

Non-foliated rocks: marble

Answer 21

non-foliated recrystallized
limestone
composed of calcite (CaCO3)
impurities result in secondary minerals, streaks and bands
these impurities are valuable in commercial marble quarries
contact or regional metamorphism

Question 22

How do fluids effect metamorphism

Answer 22

changes chemical environment, the way heat and pressure change the physical environment
- The reactive fluids remove and add ions leading to mineralogical changes

Question 23

what is hydrothermal metamorphism or alteration

Answer 23

metamorphisim when hot fluids go within rocks to chemical alter the protolith, and change the rock.

Question 24

Define regional metamorphisim

Answer 24

metamorphisim that occurs in large scale tectonic processes like collision zones.