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NAME:
GEOL 1101 LAB #2 ROCK CYCLE AND IGNEOUS ROCKS
1. List the type of rock that would form under the following situations. Types of rocks may be: plutonic
igneous rocks; volcanic igneous rocks; clastic (detrital) sedimentary rocks;
chemical sedimentary rocks; biochemical sedimentary rocks; metamorphic rocks
1A: a magma rises to a depth of 3 km below the surface and crystallizes at depth
ROCK THAT FORMS = ______________________
1B: a metamorphic rock is exposed at the surface, weathers, and the resulting broken up rock
pieces are transported by a stream, then deposited and cemented together
ROCK THAT FORMS = ______________________
1C: a small desert lake evaporates and forms a rock
ROCK THAT FORMS = ______________________
1D: a magma migrates along fractures in the crust and erupts at the surface
ROCK THAT FORMS = ______________________
1E: rocks at the boundary of two colliding plates get subjected to very high pressures and
temperatures but remain solid
ROCK THAT FORMS = ______________________
1F: microscopic plankton in the ocean make shells of calcite that accumulates on the ocean
when the plankton die
floor
ROCK THAT FORMS = ______________________
2. Match the following pictures to the types of rocks names in question 1. For example if the photo is of a
plutonic rock, the photo would match the letter in question 1 that describes the formation of plutonic igneous
rocks.
PHOTO A matches letter ________
PHOTO C matches letter ________
:
PHOTO B matches letter ________
:
PHOTO D matches letter ________
:
PHOTO E matches letter ________
:
PHOTO F matches letter ________
:
3. Define ROCK TEXTURE:
4. What is the difference in the way in which plutonic (intrusive) igneous rocks form and the formation of
volcanic (extrusive) igneous rocks?
5. Explain what has to occur before plutonic rocks can be exposed at the surface so that we can see them.
6. Using the Lecture Notes and your text, describe two ways rocks can melt WITHOUT increasing the
temperature.
7. For EACH of the two ways of melting described in question 7, list the geologic environment (tectonic setting)
where this melting method can occur.
BOWEN’S REACTION SERIES
IGNEOUS ROCK IDENTIFICATION CHART
INTERMEDIATE
MAFIC
ULTRAMAFIC
PLUTONIC FELSIC
COMPOSITION
COMPOSITION
COMPOSITION COMPOSITION
(INTRUSIVE)
TEXTURE:
phaneritic (also
called coarsegrained)
VOLCANIC
(EXTRUSIVE)
(lighter color)
GRANITE
abundant quartz, Kspar (orthoclase
feldspar); some
sodium plagioclase
may be present;
usually some
muscovite and/or
biotite also present
FELSIC
COMPOSITION
(lighter color)
RHYOLITE
TEXTURE:
light grey to pinkaphaneritic (also
purple
called fine-grained)
(darker color)
GABBRO
(green)
PERIDOTITE
abundant
amphibole and
sodium plagioclase
(white to light grey);
also biotite
dark green to
black; abundant
pyroxene and
calcium
plagioclase (dark
color)
mostly olivine;
minor pyroxene;
may have a black
rim on sample
INTERMEDIATE
COMPOSITION
MAFIC
COMPOSITION
(darker color)
ULTRAMAFIC
COMPOSITION
(green)
ANDESITE
BASALT
DIORITE
dark grey to black
RHYOLITE
ANDESITE
BASALT
porphyritic
visible quartz
and/or K-spar,
muscovite; light
grey to pink-purple
fine-grained
background
visible amphibole,
sodium
plagioclase; may
see biotite; fine
grained
background
visible pyroxene,
calcium
plagioclase; may
see olivine; dark
grey to black finegrained
background
vesicular
(abundant holes)
glassy
PUMICE
SCORIA
light grey to tan
dark brown, red, black
OBSIDIAN
QUESTION 8 is optional, and can be completed for up to 3 pts extra credit on Lab Exam 1
(rare)
(rare)
8. Use Bowen’s reaction series above and the Igneous rock identification chart to determine the compositions
A, B, C, and D; then name the rocks that form (P = plutonic; V = volcanic) below the chart.
_________________________________________________________________________
A=
P=
_________________________________________________________________________
B=
P=
V=
_________________________________________________________________________
C=
P=
V=
_________________________________________________________________________
D=
P=
V=
_________________________________________________________________________
9. What type of texture do plutonic (intrusive) igneous rocks have?
EXPLAIN how this plutonic rock texture forms.
10. What are the four types of textures that volcanic (extrusive) igneous rocks may show?
For EACH volcanic rock texture, EXPLAIN how the texture will form.
11. Using the Lecture Notes and your text, name the plutonic bodies shown on the picture below.
(A is > 100 km2 and E is < 100 km2)
A=
B=
C=
D=
E=
F=
12. The plutonic body labeled “F” in question 11 forms when magmas are very viscous. Describe what is
meant by a viscous magma, and explain the composition of magma that will be viscous.
13. The plutonic body “A” in question 11 is felsic in composition. Name the rock that composes plutonic body
“A”.
14. If the magma forming “A” erupted, what would be the name of the rock that forms?
REQUIRED IGNEOUS ROCK LIST (these are the rocks you should be able to identify
on a test, when given a photo and all necessary characteristics):
PLUTONIC IGNEOUS ROCKS: granite, diorite, peridotite
VOLCANIC IGNEOUS ROCKS: rhyolite, andesite, basalt, scoria, pumice, obsidian
15. Using the Lecture Notes, your text, and the Igneous rock chart above, name the rocks and their textures
shown below (additional information is also provided for some photos):
15A
15A TEXTURE:
15A ROCK NAME:
Minerals in 15A = quartz, K-spar (orthoclase), biotite
15B
15B TEXTURE:
15B ROCK NAME:
15C
15C TEXTURE:
15C ROCK NAME:
minerals in 15C = sodium plagioclase, amphibole, biotite
15D
15D TEXTURE:
15D ROCK NAME:
15E
15E TEXTURE:
15E ROCK NAME:
visible minerals in 15E= sodium plagioclase, amphibole
15F
15F TEXTURE:
15F ROCK NAME:
Visible mineralsin 15F: olivine, calcium plagioclase
15G
15G TEXTURE:
minerals in 15G = mostly olivine
15H
15G ROCK NAME:
15H TEXTURE
15H ROCK NAME:
15I
15I TEXTURE:
15I ROCK NAME:
15J
15J TEXTURE:
15J ROCK NAME: