Metamorphic rocks undergo substantial changes due to intense heat, pressure, or chemical fluids, often deep underground. The process of recrystallization involves minerals and grains being tightly packed together under these conditions, forming new crystal structures.
Lineation is the parallel arrangement of
minerals within metamorphic rocks
ex.Amphibolite
Quartzite and Marble dont align under intense heat
Wet rock is easier to transform than dry rock
Classifying Metamorphic Rocks
WHERE DOES THE PRESSURE COME FROM
Burial Metamorphism
Rocks formed by burial in sedimentary basins
with low temperatures and pressure.
Results in new minerals
Being buried in the ground gives the rocks
their pressure.
Pressure increases as depth increases.
TEXTURES OF METAMORPHIC ROCK
NON-FOLIATED/GRANULAR
Can occur from hot intruding igneous rock applying heat
WITHOUT adding pressure to a rock
Also form from rocks containing minerals that dont align under intense heat
Metamorphic rocks that don't display a sheet
structure.
FOLIATED/SHEETLIKE
Sheet-like structure that show what direction
pressure was applied.
EXAMPLES OF METAMORPHIC ROCKS
NON-FOLIATED
(SCRATCHES GLASS)
Quartzite
Hornfels
FOLIATED
Can't Scratch Glass:
Slate
Phyllite
Can Scratch Glass:
Shicst
Gneiss
CHEMICAL FLUID
When the solution comes into contact with
colder seawater, it causes chemical reactions
Called "Contact Metamorphosis"
HYDROTHERMAL SOLUTION(Dissolved ions in hot water)
Found along ocean floor.
HOW ARE THE ROCKS HEATED
Rocks can also be heated by the the crust of the Earth
Temperature of crust increases by 20-30 C degrees per kilometre
CONTACT METAMORPHISM
Rocks make contact with magma, but are not melted
REGIONAL METAMORPHISM
Molten rock near the rock that heats it up
HOW METAMORPHIC ROCKS FORM
RECRYSTALLIZATION
Recrystallization occurs under intense temperature and pressure where grains, minerals and rock materials are packed closer together.
This creates a new crystal structure
Rocks buried deep underground that are subjected to extreme heat and pressure or chemical fluids.
They are heated, folded, squashed, stretched out, and put under a lot of pressure.
