Chapter 3 - Igneous Rocks Flashcards
If a body of magma becomes more felsic, its viscosity will:
a. increase
b. decrease
c. stay the same
a. increase
Obsidian has a _________ texture.
a. glassy
b. fine-grained
c. coarse-grained
d. vesicular
e. porphyritic
a. glassy
The Sierra Nevada Mountains are an example of a pluton called a:
a. laccolith
b. stock
c. batholith
d. dike
e. sill
c. batholith
Think back to Bowen’s Reaction Series to respond to this. If a body of magma is subjected to fractional crystallization, the rock that results is expected to be:
a. identical in chemical composition to the magma
b. more mafic than the magma
c. more felsic than the magma
c. more felsic than the magma
Magma that might have cooled slowly to produce a diorite is instead erupted at Earth’s surface. It would chill rapidly and produce a(n) ________.
rhyolite
granite
basalt
andesite
andesite
(T/F) Peridot is the gemstone variety of biotite.
False
In accordance with Bowen’s reaction, this mineral would crystallize at the highest temperature.
a. quartz
b. amphibole
c. olivine
d. feldspar
c. olivine
(T/F) Peridotite is an ultramafic igneous rock.
True
Most commonly felsic igneous rocks:
a. contain more iron and magnesium than intermediate rocks
b. are lighter in color than mafic rocks
c. are darker in color than mafic rocks
d. are found in oceanic crust
b. are lighter in color than mafic rocks
(T/F) It is impossible for granite to form from magma rising to the surface at a mid-ocean ridge.
True
All other factors being equal, intrusive rocks that form deep within Earth ___________ than intrusive rocks that cool near the surface.
a. are more felsic
b. contain smaller proportion of volatiles
c. cool more rapidly
d. cool more slowly
d. cool more slowly
Magma composition can change through:
a. crystal settling
b. assimilation
c. partial melting
d. all these
d. all these
(T/F) Granite and rhyolite have the same chemical composition but different textures.
True
🔴 As compared to coarse grained igneous rocks, all fine-grained igneous rocks:
a. solidify at lower temperatures
b. solidify at higher temperatures
c. cool and solidify more slowly
d. cool and solidify more quickly
a. solidify at lower temperatures?
As a magma composition changes from mafic to felsic, which of the following elements increases?
a. calcium
b. magnesium
c. iron
d. silicon
d. silicon