EXAM 2 Igneous Rocks
magma
BENEATH Earth's surface, often generated in upper asthenosphere and lithosphere in magma chambers
lava
ON Earth's surface, composed of silicate minerals
A porphyritic texture where large crystals are embedded in a matrix of small crystal may form when ________.
a magma that has partially crystallized slowly moves to a different location where it then cools rapidly
rock
a solid aggregate of one or more minerals, or mineral material
Most commonly, felsic igneous rocks ________________.
are lighter in color than mafic rocks
plutons
blob-shapes intrusions that solidify from magma chambers
Igneous rock is formed ________.
by crystallization of magma
As compared to coarse-grained igneous rocks, fine-grained igneous rocks ______________.
cool and solidify more quickly
extrusive rock crystal size?
cool fast/small crystals
intrusive rock crystal size?
cool slowly/large crystals
igneous rocks
cooling of molten rock
dikes
cut across rock layers
composition
felsic, intermediate, mafic, ultramafic
texture
fine(aphanitic), coarse(phaneritic)
slow rate of cooling
forms large crystals
fast rate of cooling
forms small crystals
phaneritic texture
individual mineral grains can be seen w the naked eye
"formed by fire" examples
magma and lave
rocks classified according to:
mineral composition, chemical composition, texture, how they were formed
porphyritic texture
mixture of coarse and fine crystals, two-stage cooling (slow then fast)
mafic
more dark minerals (black), Augite
felsic
more light minerals, Quarts or K-Feldspar
sills
parallel to rock layers
An irregular-shaped and blob-like igneous rock body that cooled beneath the surface of Earth is a ________________.
pluton
Which igneous texture is characterized by two distinctively different crystal sizes?
porphyritic
Coarse-grained granite is most similar in mineral composition to fine-grained ________.
rhyolite
"formed by fire"
rocks formed from molten rock material
plutonic or intrusive rocks
rocks formed inside Earth, phaneritic, several colors **rich in Magnesium and Iron
volcanic or extrusive rocks
rocks formed on the surface, aphanitic(crystals too small to see w naked eye), single color, glassy
intermediate
same amount of dark minerals as light (salt and pepper), Hornblende
rock cycle
system that links subsurface processes driven by Earth's internal heat to surface processes driven by solar energy
Intrusive igneous rocks are often coarse-grained because ________.
the slow cooling at depth allows large crystals to grow
The mineral olivine is characteristic of a ________ magma.
ultramafic
batholith
vast composite, intrusive, igneous rock formed by the intrusion of numerous plutons in same region
ultramafic
very dark in color, mostly olivine (green)
If magma or lava cools quickly, the resulting igneous rock will have ________.
very small crystals