Please enable JavaScript.
Coggle requires JavaScript to display documents.
Metamorphic Rocks (Contact metamorphic rocks (Marble (Crystals of calcite,…
Metamorphic Rocks
Contact metamorphic rocks
Marble
Crystals of calcite, granoblastic, High Grade
Hornfels
Totally crystalline, Dark minerals= Cordierite, Grey/white minerals= Andalusite, High grade
Metaquartzite
Fused Quartz crystals, granoblastic, High Grade
Spotted Shale
Partial crystallisation, porphyroblast of Chiastolite Andalusite (contains inclusions of unaltered clay)
How do rocks change
minerals recrystallise
Texture changes by growth of new minerals
Foliation caused by pressure
3 types
Regional
Extensive change in zones where tectonic plates collide
Dynamic
Localised change along fault zones
Contact
Localised change around magma intrusion
Regional metamorphic rocks
Schist
medium grade, shisosity, foliated mica, porphroblast of garnet, crystalline, Augen structure (Mica wrapped round garnet)
Gneiss
high grade, gneissose, banded colours, coarse grained, porphyroblastic, crystalline
Slate
Low grade, Slaty cleavage, foliated chlorite, granoblastic, fine grained, crystalline
Sources of heat and pressure
Pressure
Weight of rock
Tectonic movement
Heat
Pressure
Radioactive decay
Magma
Metamorphism and plate tectonics