METAMORPHISM AND

METAMORPHIC ROCKS

• Metamorphism

process by which rocks undergo changes in mineralogy, texture, or chemical composition

WHERE? in the crust and mantle

Metamorphic Agents: internal heat, weight of rock, horizontal pressures of deformation result in:

1. temperature

2. pressure

Metamorphic Agents: (cont.)

2. pressure

i. confining

ii. directed

3. fluids - metasomatism

Types of Metamorphism

1. Contact

i. plate convergence (with subduction)

ii. oceanic and continental hot spots

iii. deformed mountain belts

Types of Metamorphism

2. Regional

i. plate subduction

ii. plate convergence

Types of Metamorphism

3. Hydrothermal - chemical

4. Burial

5. Dynamic or shear (cataclastic)

Classification - Texture and Mineralogy

1. foliated - foliation, schistosity

http://www.guilford.edu/original/academic/geology/imagelibrary/001.JPG

Classification - Texture and Mineralogy

2. non-foliated

Classification - Texture and Mineralogy

3. porphyroblasts

Grade of Metamorphism

1. Regional vs. Contact

i. low grade to high grade

Grade of Metamorphism

1. Regional vs. Contact

ii. index minerals

Grade of Metamorphism

1. Regional vs. Contact

iii. metamorphic zones and facies

(1) different rocks form from different parent rocks

different rocks form from grades of metamorphism