GEO1115_2021_Activity10.1F
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University of Ottawa *
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1115
Subject
Geology
Date
Dec 6, 2023
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docx
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Uploaded by jaytwimb
THEME 10 – METAMORPHIC ROCKS
[ 20/20 : A+ ]
A
CTIVITY
10.1F – T
ECHNICAL
QUESTIONS
(
/20)
Reference material:
-
Lecture of associated theme (Brightspace)
-
Glossary (
https://mysite.science.uottawa.ca/dumas/
)
-
Reference document “Section of the lab manual” in Brightspace
Activity:
1.
Refer to the figure below to answer the following questions. (
/6)
a)
What type of metamorphism is illustrated on this figure? (
/1)
Contact metamorphism
b)
Identify how the metamorphic grade varies with respect to the red arrows in this diagram, and
explain why it is so. (
/3)
In respect to the red arrows, it is an increasing metamorphic grade. This is because the
temperature closest to the magma will be the highest therefore causing the highest degree of
metamorphism.
c)
Draw a simple version of the P-T diagram and mark on your diagram the area representing this
type of metamorphism. (
/2)
2.
Answer the following questions about foliation. (
/7)
a)
Define in your own words the concept of foliation. (
/2)
Foliation is a texture of metamorphic rocks made of the parallel arrangement of planar features
in said rock such as minerals, grains, and crystals. This develops when stress is exerted on the
rock unevenly or nonuniformly, also known as differential pressure.
b)
Name the three mechanisms by which foliation can form. (
/3)
rotation or flattening of minerals and grains, recrystallization of pre-existing minerals, or
crystallization of new minerals
c)
Name the type of pressure that is necessary for the development of a foliation in a rock during
its metamorphism. (
/1)
Differential pressure
d)
Give an example of a tectonic context where you would expect to find the type of pressure
identified in “c)” and where the metamorphic rocks would therefore be foliated. (
/1)
Convergent zones of tectonic plates during dynamo-thermal metamorphism
3.
Based on the information presented in the reference material “Section of the Lab Manual” posted
in Brightspace, and the lecture notes, answer the following questions about the four types of
foliation. (
/7)
a)
Name the four types foliation in increasing order of metamorphic grade, and also indicate for
each (in parentheses) the name of the rock showing this metamorphic texture. (
/4)
Slaty Cleavage (slate)
Phyllitic Texture(phyllite)
Schistosity (schist)
Gneissosity (gneiss)
b)
Highlight the difference(s) in the appearance of the 2
nd
and 3
rd
types of foliation. In addition,
highlight other textural differences that accompany these foliations, which would therefore help
you to better distinguish rocks with these different foliations. (
/3)
Phyllitic Texture : splits in parallel, even sheets along flat surfaces
Schistosity : breaks along slightly undulating surfaces
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