Metamorphism the process that creates metamorphic rocks All made from the alteration of existing rocks by excessive pRESSURE ANDOR ID: 583855
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Slide1
Organizing Metamorphic Rocks
Metamorphism:
the process that creates metamorphic rocks.
All made from the alteration of existing rocks by excessive…
pRESSURE AND/OR hEAT
The most obvious effect is the rearrangement of minerals grains into bands or stripes called foliations.
Temperatures above 200oC will create new minerals in the rock or will enlarge existing minerals known as recrystallization
Two types of MR:
sorted by texture
1.
Foliated
2. Non-Foliated
– bands or stripes
The mineral grains in rocks subjected to extreme pressure often rearrange themselves in a parallel fashion.
- no particular direction
Examples:
Foliated –
Non-Foliated –Slide2
How does metamorphism happen?
What force has the power to squish & heat rocks until the crystals change?
Regional Metamorphism
Occurs over large areas
(as big as states or countries!) Existing rock will change by the heat and pressure created during mountain building. (A) continents collide (B) ocean crust subducts
Slide3
How does metamorphism happen?
What force has the power to squish & heat rocks until the crystals change?
Contact metamorphism
Occurs over small areas. Existing rock is heated when it comes in contact with magma or lava.
Slide4Slide5
The lava flow (in gray) seen in this road cut has baked the mud beneath it into brick.
This sill baked the adjoining limestone into marble.Slide6
Metamorphic Rocks Come From “Other Rocks”
Gneiss
Granite
IR
Schist
BasaltIR
Marble
Limestone
SR
Quartzite
Sandstone
SR
Gneiss
Schist
MR
Schist
Phyllite
MR
Phyllite
Slate
MR
Slate
Shale
SR
Metamorphic Rock
Parent Rock
Rock Type