GEOL104_Lab7_PlanetaryVolcanism_F2023_TH
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GEOL104: Exploring the Planets
LAB 7: Planetary Volcanism
Name:
OBJECTIVES
:
I.
Introduce Bowen’s Reaction Series and connect properties of minerals to concepts of
density learned during the Material Properties Lab.
II.
Identify rock types that form during volcanic processes on terrestrial planets and moons.
III.
Develop an understanding of volcanic processes.
IV.
Learn how to interpret images for scientific purposes.
PART 1: IGNEOUS MINERALS AND BOWEN’S REACTION SERIES
Petrologist Norman L. Bowen (1887–1956) observed that in
igneous rocks
, certain
minerals always occur together, and these mineral assemblages exclude other minerals. Curious
as to why, and with the hypothesis that these observations have to do with the temperature at
which the rocks cooled, Dr. Bowen conducted experiments on igneous rocks by combining
variations of rocks and heating them to various temperatures, and then cooling them. Through
these studies he showed that the common
igneous minerals crystallize from magma at different
temperatures in a sequence
, and
that minerals occur together in rocks with others that crystallize
within similar temperature ranges, and never crystallize with other minerals.
This relationship
can explain the main difference between
mafic
and
felsic igneous rocks
: Mafic igneous rocks
contain more mafic minerals, and therefore, crystallize at higher temperatures than felsic igneous
rocks. This is even seen in lava flows, with felsic lavas erupting hundreds of degrees cooler than
mafic flows.
1
Figure
1
:
Bowen's
Reaction
Series.
Image
Credit:
http://www.
geologyin.c
om/2014/0
9/how-
does-
bowens-
reaction-
GEOL104: Exploring the Planets
The above chart (Figure 1) shows the sequence of minerals, known as
Bowen’s Reaction
Series
, along with which types of rocks they are abundant in and the relative temperature of the
magma that they form in.
Bowen’s work laid the foundation for understanding
igneous
petrology
(the study of rocks) and resulted in his book,
The Evolution of the Igneous
Rocks
in 1928.
Question 1:
Based on
Bowen’s Reaction Series
, which composition category will have formed at high
temperatures and which will have formed at low temperatures (fill in the blank brackets):
Mafic
compositions are likely to be formed in [
lower
]
temperature environments,
while
Felsic
compositions are likely to be formed in [
higher
]
temperature environments.
Question 2:
For each of the following minerals, describe the color based on the SketchFab links provided on
page 3 and use
Figure 1
from page 1 to determine the composition (right column):
Sample #: Mineral Name
Color
Composition (Ultra Mafic,
Mafic, Intermediate, Felsic)
1.
Olivine
Grey with spots of green
Ultra Mafic
2.
Pyroxene
Dark green, black and some
brown spots
Ultra Mafic
3.
Amphibole
Black w/ tan/brown
Mafic
4.
Biotite
Black and dark brown edges
Mafic
5.
Albite
(Sodium Feldspar)
White and yellow
Mafic
6.
Orthoclase
(Potassium Feldspar)
Orange and black
Felsic
7.
Anorthite
(Calcium Feldspar)
Black, white and brown
Ultra Mafic
8.
Muscovite
Grey-greenish
mafic
9.
Quartz
Black and white tips
Intermediate
2
GEOL104: Exploring the Planets
Question 3:
Based on the density chart (
Table 1
) from the
Lab 2: Planetary Materials
, and the order of the
minerals in
Figure 1
of this lab, what could you say about the trend of mineral density
and
Bowen’s Reaction Series?
In Bowen's Reaction Series, mineral density is frequently associated
with crystallization sequence. Minerals that crystallize at higher temperatures have higher
densities than those that crystallize at lower temperatures.
SKETCHFAB LINKS:
Sample 1:
Olivine:
https://sketchfab.com/3d-models/arizona-xenolith-in-basalt-e52ec4efb7304d05ac60278c959710cd
(the colorful portion)
Sample 2:
Pyroxene:
https://sketchfab.com/3d-models/olive-green-double-terminated-enstatite-
crystal-64defcb57ac44be39dc79f1e6ac0da7b
Sample 3:
Amphibole:
https://sketchfab.com/3d-models/hornblende-
8cbecc6babfd4f73882ea5d13c2f13e6
(the darker portion)
Sample 4:
Biotite:
https://sketchfab.com/3d-models/biotite-
43e6b5e056ce4d75936bb34014f89179
Sample 5:
Albite:
https://www.minerals.net/MineralImages/albite1.jpg
(See Fig. 1 for composition)
Sample 6:
Orthoclase:
https://sketchfab.com/3d-models/orthoclase-
0b14082d2d8c452b8ae813de7a548e60
Sample 7:
Anorthite (Labradorite):
https://sketchfab.com/3d-models/labradorite-8-27-
e8f3a8002bde4bc4a3e4db8d32c7d320
Sample 8:
Muscovite:
https://sketchfab.com/3d-models/muscovite-
a68bdd4145dc4a3596b635a37af3adfe
Sample 9:
Quartz:
https://sketchfab.com/3d-models/quartz-crystal-cluster-
80a2f60700ac4593955392cac20b9415
Sample A:
Granite:
https://sketchfab.com/3d-models/biotite-granite-
ed0d206cc713484da07fa6cb645ec875
Sample B:
Rhyolite:
https://sketchfab.com/3d-models/rhyolite-11-8-29-
2019-607335bbaf3b4bcaac31f1926890ff93
Sample C:
Basalt:
https://sketchfab.com/3d-models/vesicular-basalt-
9a2f4580bbda4adf8c3feb5460449874
Sample D:
Gabbro:
https://sketchfab.com/3d-models/gabbro-brazil-
e004b43d7b3b4e8da8f3b79418a35134
Sample E:
Anorthosite:
https://sketchfab.com/3d-models/adirondack-
anorthosite-d513402469f648baa1e5ea345e702d45
3
Image of
anorthosite mineral
grains
up close.
Click
here
for link of image.
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GEOL104: Exploring the Planets
4
GEOL104: Exploring the Planets
PART 2:
INNER SOLAR SYSTEM VOLCANISM
Igneous rocks are rocks that formed by crystallization (solidification) of magma.
Their
texture can tell us a lot about how they formed. Rock texture is the size, arrangement, and degree
of uniformity of mineral crystals in a rock.
For example, a ‘
coarse-grained
’ rock has
larger
(visible) crystals or grains, whereas the crystals or grains in ‘
fine-grained
’ rocks are
smaller
or
may only be visible with a hand lens or microscope. Coarse-grained igneous rocks
– having
larger mineral crystals – form where the crystals have had time to grow before the magma
solidified, because of slow cooling of the magma.
Conversely, fine-grained igneous rocks
have
crystals that are smaller, because they have not been able to grow very big before the magma
solidified due to rapid cooling.
Geologists use two terms to identify whether an igneous rock cooled to a solid in the
Earth, or if it erupted as a lava and therefore cooled on the surface of the Earth:
intrusive
and
extrusive
. The
surface of the Earth is the lowest temperature
that rocks experience in their
history, as
temperature increases with depth beneath the surface
. This is called the
geothermal
gradient
:
http://www.geologyin.com/2014/12/geothermal-gradient.html
Question 4:
Based on what you learned about temperature and grain size from above, which type of igneous
rock should be coarse grained and which is more likely to be fine grained (fill in the blanks in the
brackets):
5
GEOL104: Exploring the Planets
Intrusive
igneous rocks are likely to be [
coarse
]
grained, while
extrusive
igneous rocks
are likely to be [
fine
]
grained.
Question 5:
Temperature
and cooling rate
are two different factors in rock type determinations. One of these
factors determines the composition of the rock, while the other factor determines the grain size
relative to other rocks of a similar composition. The left column (i–iv) lists properties of igneous
rocks while the right column (A–D) lists temperatures and cooling rates.
Match the respective
properties based on what you have learned so far
:
Coarse-Grained – Slow Cooling
Fine-Grained – Rapid Cooling
Felsic – High temps
Mafic – Lower Temps
i) Coarse-Grained
ii) Fine Grained
iii) Felsic (light)
iv) Mafic (dark)
A)
Lower Temps.
B)
Higher Temps.
C)
Rapid Cooling
D)
Slow Cooling
SKETCHFAB links for rock samples
are provided on Page 3 for Questions 6–9!
Question 6:
Sample A,
granite,
and sample B,
rhyolite
, have nearly an identical composition, which is
mostly quartz and plagioclase (albite), making them the same composition but yet they have
different textures, or grain sizes.
Look closely at each rock and based on the relative sizes of
their mineral crystals,
write down which of these rocks is intrusive and which is extrusive
based on grain size.
Based on what you have learned so far, what is the composition of these
two rocks?
TextureComposition
Granite:
intrusive
coarse grained/felsic
Rhyolite:
extrusive.
Fine grained/felsic
Question 7:
Sample C,
basalt,
and sample D,
gabbro
, have nearly an identical composition, which is mostly
quartz and plagioclase (albite), making them the same composition but yet they have different
textures, or grain sizes.
Look closely at each rock and based on the relative sizes of their mineral
crystals,
write down which of these rocks is intrusive and which is extrusive based on grain
size.
Based on what you have learned so far, what is the composition of these two rocks?
TextureComposition
Basalt:
extrusive.
Fine/mafic
Gabbro:
intrusive.
Coarse/mafic
Question 8:
6
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GEOL104: Exploring the Planets
Sample E is
anorthosite
, a rock that makes up a larger portion of the Moon’s crust. Its cooling
history is similar to granite and gabbro.
Using anorthosite’s color to approximate its
composition, is it compositionally
similar to granite or to gabbro?
More similar to granite than
gabbro
Question 9:
Using anorthosite’s grain size to approximate cooling,
is Sample E intrusive or extrusive?
Intrusive
PART 3: GLOBAL VOLCANISM
Anorthosite composes the majority of the lunar highland and likely was emplaced during
cooling of a magma ocean during the early stages of lunar formation. The light color of the
highlands is attributed to minerals in anorthosite being rich in Ca and Na. The dark portions of
the lunar surface are referred to as the Mare and are known to be rich Fe and Mg.
Global topographic map of the Moon with the colors representing elevation from lowest (purple to black) to highest (red to
white) taken by LOLA on LRO. Source: NASA
7
This false-color photograph (on the left),
helpful for interpreting the
surface soil
composition
, is a composite of 15
images of the Moon taken through three
color filters by Galileo's solid-state
imaging system during the spacecraft's
passage through the Earth-Moon
system on December 8, 1992.
Areas appearing
red generally
correspond to the lunar highlands
,
while
blue to orange shades indicate
the ancient volcanic lava flow of a
mare
, or lunar sea.
Image Credit:
GEOL104: Exploring the Planets
Question 10:
Based on what you have learned about in this lab and previous labs,
hypothesize about how
these two different sections of the lunar crust were formed
, including the sequence/relative
timing and what events may have led to different compositions.
Answer must be multiple full
sentences and reference properties of igneous minerals and rocks for full credit
.
Hints:
You can use:
1. Density and planetary differentiation concepts
2. Planetary tectonics and relative age dating concepts
AND/OR
3. Information about where different types of volcanic rocks (mafic/felsic) and
minerals occur
Answer
:
The development of different parts of the lunar crust can be thought by igneous materials,
planetary differentiation, and relative age dating principles. The lunar crust is divided into two
sections which are the highlands and the maria, which differ in composition and age.
The anorthosite dominated highlands seem to have started early in the Moon's history. This type
of rock is coarse-grained indicating that it cooled slowly from a molten state. It has been argued
that these formations arose from a magma ocean following the Moon's original formation, where
less dense minerals and floated to the surface due to density stratification processes during
planetary differentiation.
Question 11:
Research question:
Search online for an example of a volcanic feature somewhere in the solar
system other than Earth or the Moon and insert an image of that feature below.
Describe the
volcanic feature (where and what it is) and its origin (how did it get there?).
Your answer will
need to be at least several sentences to receive full credit.
This will require you to do some
research online to find information about your chosen feature. Remember to cite your sources!
Loki Patera is a huge volcanic crater that spans 202 kilometers (126 miles). It is well-known for
its intense volcanic activity, which results in plumes and lava flows. The volcanic activity on
8
GEOL104: Exploring the Planets
Loki Patera is thought to be triggered by tidal heating caused by gravitational interactions
between Jupiter, its neighboring moons, and itself. These tidal forces cause severe internal
heating on it, resulting in volcanic eruptions and the island's high volcanic activity. The magma
beneath Loki Patera erupts on a regular basis, forming large lava lakes and plumes that
contribute to Io's continually shifting surface. Loki Patera is an important example of how tidal
pressures and internal heating may drive volcanic activity on celestial worlds other than Earth,
altering their surfaces and providing insights into the geological processes taking place in our
solar system's furthest reaches.
9
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