Final Flashcards
(19 cards)
Foliation
Planar structure that is produced by mineral growth
Examples of foliation
- slaty cleavage: fine-grained, easily split
- schistosity: medium coarse-grained, parallel sheet-like
- gneissic layering: random orientations, coarse-grained with alternating light and dark bands of quartz, potassium, feldspar, and ferromagnesian
- mylonitic texture: stretched and flattened grains
Metamorphic rock classification (from high to low grade)
- zeolite
- greenschist
- amphibolite
- granulite
- blueschist
What grade is biotite garnet facies
Intermediate
6 metamorphic categories
- regional metamorphism
- contact metamorphism
- cataclysmic or dynamic
- convergent boundary
- burial
- impact
Where might regional metamorphism take place, and what happens as a result?
- at the foot of a mountain
- change blocky minerals to platy minerals
Where might contact metamorphism take place, and what happens as a result?
- baked zones next to magma intrusions
- produces aureole (baked contact zone) where hornfels are found
Hornfels
Fine-grained, dense, dark rocks
Cataclastic metamorphism (grinding during faulting)
Structures produced in a rock as a result of severe mechanical stress during dynamic metamorphism (including bending, breaking, and granulation of minerals)
What does cataclastic or dynamic metamorphism produce
Coarse fault breccias and fine-grained mylonites
Where is convergent boundary metamorphism and what develops as a result?
- subducting plate boundaries
- blueschist metamorphic rocks
What is special about blueschist rock
Develops in low temperature, but high pressure areas (i.e. subduction zones)
Burial metamorphism
Pressure from being buried changes minerals
What causes impact metamorphism
Meteorite collision that results in high pressure
Four metamorphic rock types
- slate: microscopic mica flakes
- phyllite: barely macroscopic mica flakes
- schist: larger visible mica flakes
- gneiss: banded light and dark rock
What minerals are responsible for what colors in metamorphic rocks?
- green=chlorite
- yellow/white= zeolite
Common protoliths and metamorphic rock types
- sandstone=quartzite
- limestone=marble
- shale/mudstone= slate phyllite & schist gneiss
- granite=granite gneiss
- peat=coal/anthracite
- basalt=amphibolite
Compositional rock groups (general characterization)
- protolith = parent rock
- pelitic rock = originally had lots of clay
- calcareous (CaCO3) = originally limestones/ dolomites
- mafic rocks = basalts or gabbros
- quartz feldspathic = igneous or sedimentary
How is coal produced and what are the different grades?
- plant material under pressure of burial in marine and swamp areas
- peat, ignite, sub bituminous, bituminous cba, sub anthrocite, meta anthrocite
