Igneous Rocks
Chapters 3 & 4
Arcadia Nat’l Park, Maine
How do Igneous Rocks form?
What is Magma?
What is Lava?
How do they form?
• What are the two categories of igneous rocks?
• How does each type form?
How are plutons & volcanoes related?
How Hot Is Lava?
• How long does it take lava to cool?
Where Does Magma Originate?
Where are Magma Chamber located?
What is the Geothermal gradient?
How does pressure affect
the melting point of a
rock?
How does water affect rocks at depth?
TEXTURES of Igneous Rocks
• What is Texture?
• What does a rock’s grain size indicate?
What is Aphanitic texture and what does it indicate?
TEXTURES of Igneous Rocks (cont.)
• What is Glassy texture & what does it indicate?
• What is Vesicular texture & what does it indicate?
a
b
TEXTURES of Igneous Rocks (cont.)
What is Phaneritic texture & what does it indicate?
TEXTURES of Igneous Rocks (cont.)
• What is Porphyritic texture & what does it indicate?
TEXTURES of Igneous Rocks (cont.)
• What is Pyroclastic (fragmental) texture & what
does it indicate?
Magma Composition
What is the most abundant constituent of magma?
• What characteristics do Felsic magmas have?
• What characteristics do Intermediate magmas have?
• What characteristics do Mafic magmas have?
• What characteristics do Ultramafic magmas have?
Composition of Igneous Rocks
• What controls the type of rock that forms?
What are the 4 Magma Modification Processes?
What is Crystal settling?
What is
Assimilation?
How does it affect
a magma’s
composition?
• What is Magma mixing & how does it affect a magma’s
composition?
Who discovered Bowen’s Reaction Series?
What is Bowen’s
Reaction Series?
How are Igneous Rocks Classified?
• Felsic are _______ colored b/c they’re composed
of orthoclase, Na-plagioclase, & quartz.
A
Rhyolite (A)
B
Granite (B)
[most common intrusive rock]
Pegmatites are __________________ (grains >1 cm
in diameter) & are mineralogically similar to ______.
• These mineral grains crystallized from ______________
____________________________________________.
Intermediate contain _________ amts of
_________ colored ferromagnesian silicates, &
_________ colored feldspar.
B
A
Andesite (A)
[erupts from island arcs]
Diorite (B)
Mafic rocks are ______colored b/c they’re largely
composed of
______________________________________.
A
B
Basalt (A)
Gabbro (B)
Ultramafic are _____ colored b/c they are comp. of
________________________________ silicates.
What are Peridotites composed of olivine?
Where are Peridotites formed?
What is Volcanic Glass composed of?
What rock type has a similar composition?
Why can volcanic glass be different colors?
What are vesicles & how are they formed?
Obsidian
Pumice
What are Tuffs?
How do magmas move?
What is Magma type at Divergent Margins & Hot Spots?
What are the Magma Types at Convergent Margins?
How are these magmas
formed?