GEO 401 Final Exam Review 2023 with 100% correct answers

If a magma chamber undergoes fractional crystallization during cooling, how will the remaining magma
differ from the parent magma? – correct answer It will be more felsic
What type of magma can be produced when upper-mantle peridotite undergoes decompression along
mid-ocean ridges? – correct answer basaltic
Mineral – correct answer -Naturally ocurring
-inorganic element or compound
-has an orderly internl structure and characteristic chemical composition, crystal form, and physical
properties
Example of a material that is NOT considered a mineral – correct answer glassy materials in fast cooling
basalt
In which subsystem is the Earth’s magnetic field generated? – correct answer Geodynamo system
Isotopes – correct answer Atoms of the same element that have different numbers of neutrons
What needs to happen to bond Na and Cl to make NaCl? – correct answer One electron is transferred
from the sodium atom to the chlorine atom
How are elements in the periodic table organized? – correct answer in order of increasing number of
protons
Example of a type of convergent plate boundary – correct answer Subduction zone

Principle of Uniformitarianism – correct answer the geologic processes we observed today have
operated in the past
Which boundary does the Mohorovic Discontinuity coincide with? – correct answer crust-mantle
Which mineral crystallizes from magma at the lowest temperature? – correct answer quartz
What do the magnetic stripes of alternating polarity along the mid-ocean ridges indicate? – correct
answer Magnetic reversals of the Earth’s magnetic field when the Earth’s magnetic north and south
poles flip
How does the oceanic crust compare to the continental crust? – correct answer it is denser and thinner
Which rock has the highest silica content and is classified as a felsic rock? – correct answer Granite
Which silicate mineral is commonly found in mafic igneous rocks? – correct answer pyroxene
Which conditions can cause a rock to melt in Earth’s deep interior? – correct answer -addition of volatiles
such as water into the rock
-decompression (a decrease in pressure)
-an increase in temperature
True statements about the age of geological events – correct answer -the earth was formed 4.6 billion
years ago
-the oldest rocks on the continental crust were 4 billion years old
-the oldest rocks on the ocean floor were 180 million years old
On a map of the ocean floor, what are the boundaries between normally magnetized ocean crust and
reversely magnetized oceanic crust called? Why are they called this? – correct answer isochrons;
because they represent the same ages of the rocks

Which mountain range is the product of continent-continent convergence? – correct answer the
Himalayas
Which of the following statements is FALSE about the Plate Tectonics Theory?
A) Lithosphere is the outer rigid shell of the earth. The dozen pieces of the large plates are composed of
the curst and part of the upper mantle
B) Asthenosphere is part of the mantle beneath the lithosphere (to ~400 km in depth)
C) The Plate Tectonics Theory is a Unifying Theory in Geology like the Evolution by Natural Selection in
Biology
D) The lithosphere rides on top of the asthenosphere, but can NOT penetrate the asthenospheres at
subduction zones because it is too RIGID – correct answer D) The lithosphere rides on top of the
asthenosphere, but can NOT penetrate the asthenospheres at subduction zones because it is too RIGID
The basic building blocks to all silicates are the SiO4 tetrahedra that are linked in a variety of ways in
three dimensions. Which one of the following statements about major silicate materials is FALSE?
A) Olivine is an abundant mineral of the upper mantle and is formed through the isolated SiO4
tetrahedra
B) Mica group minerals such as biotite and muscovite are called sheet silicates because they are formed
by layered SiO4 tetrahedra
C) Quartz and feldspar are all framework silicates
D) Pyroxene is a single-chain silicate and has the chemical formula of (Mg,Fe)2SiO4 – correct answer D)
Pyroxene is a single-chain silicate and has the chemical formula of (Mg,Fe)2SiO4
Fe2+ and Mg2+ cations are similar in size and both have a +2 positive charge. Therefore, we would
expect iron and magnesium to – correct answer substitute for each other easily in silicate minerals
Which 2 minerals are NOT an example of polymorphism? – correct answer Chert and calcite
What is the major classification of igneous rocks dependent on? – correct answer -texture
-the relative proportion of silicate minerals
Which of the following statements about the three rock types is FALSE?

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