Section 5- Metamorphic Rocks

Question 1

metamorphism definition

Answer 1

mineralogical and structural change of rock due to physical and chemical conditions

-rocks minerals change from less stable to more stable
-cystals grow larger
-crystals realign
-rock density increases

Question 2

Agents of metamorphism

Answer 2

1. Heat
   - most imporant, heat drives recrystallization, creating newer more stable minerals
   2.Pressure(stress)
   -increases with depth and with tectonic activity
   3.chemically active fluids
   - transport heat and ions insolution and promote recystalization

other factors- rock/mineral composition, time

Question 3

Progression of shale with metamorphism and relation to grade

Answer 3

Shake->slate->phyllite->schist->gneiss
low grade —-> high grade

Question 4

foliation

Answer 4

repetitive layering in metamorphic rocks due to directed pressure
flat minerals rotate or recrystalize in a preferred orientation (perpendicular to pressure direction)
foliated rock examples:
- slate, phyllite, schist, gneiss(high grade metamorphism)

non-foliated rocks
Lack layered texture, more random. Form under high temperatures and uniform pressure(contact metamorphism)
examples: quartzite, marble

Question 5

types of metamorphism

Answer 5

1.contact metamorphism
- due to heat from adjacent magma
-metamorphises rocks in immediate contact
-produces non foliated rocks (ex quartzite, marble)
-occurs in areas surrounding igneous intrusions, like sills and dikes
-low pressure high temp
2.regional metamorphism
-occurs along convergent plate boundaries (compressional stresses)
-high pressure(produces foliation), high temp

Question 6

engineering properties

Answer 6

non-foliated rocks are stronger than foliated
foliated tend to fail along foliation planes